United States Office of Atmospheric EPA-430-R-93-007 Environmental Protection Agency and Indoor Air Programs June1993 United States Environmental Protection Agency

II 

# erslo Office of Atmospheric and Indoor Air Programs 

# serfs 

# a EPA-430-R-93-007 June 1993 

# (



# at

# User's Version 1. 0

Prepared for U.S. Environmental Protection Agency Global Change Division

by Richard Merriam Anthony Verone He Feng
Arthur D. Little, Inc. Cambridge, Massachusetts

02140



### March 1993

ADL Ref. 67895 

# ( 

# eratorram User's anual Version 1.0

Prepared for U.S. Environmental Protection Agency Global Change Division
by Richard Merriam Anthony Verone He Feng

Arthur D. Little, Inc. Cambridge, Massachusetts 

### 02140

March 1993 

# is

ADL Ref. 67895NOTICE Installation Instructions for the User in a Hurry

Section 2 of the ERA User's Manual contains full instructions for installation of ERA. The new user is advised to read this material. For the user in a hurry to try out the program, and who will thenread the manual, please pay attention to the information summarized here. Program Diskettes

. Disk 1 contains the program and the basic data files. Disk 2 contains files used to carry out the EPA Multiple Pathways analyses. The user is advised to work initially with the files supplied on Diskette 1. Virus Checking. The diskettes have been checked using a commercial product. An additional check by the user, prior to installation, is recommended. Install on

. Create a directory \ERA on a hard disk and copy all the files on Diskette 1 to this directory. It is not necessary to make any path assignments. 

### COMMA ND.C®M. The rootdirectory of the disk containing the \ERA directory must have a copy of COMMAND.COM, otherwise ERA will not work. README.DOC. Type out or print file README.DOC. The file gives important information relating to the computer hardware requirements and to methods of configuring ERA to work with it. SETUP.D)AT. This file contains information relating to the default hardware expected by ERA. After reading README.DOC (and Section 2 of the manual), make any necessary changes to SETUP.DAT with an ASCII text editor. If you don't do so, the program might not work properly on your computer. Math Co-Processor. ERA uses some very intensive calculation methods. The machine must have a math co-processor to run ERA. 

### Help Menus. Extensive Help menus are built into ERA at all levels. Press the Fl function key to request the menu. The program manual assumes that the user accesses the Help menu as the primary means of resolving program data questions. Start ing the Program

. Type ERA and press the <Enter> key. NOTICE Installation Instructions for the User in a Hurry
Section 2 of the ERA User's Manual contains full instructions for installation ofERA. The new user is advised to read this material. Fortheuserin ahurryto tryouttheprogram, and who will 

### thenread themanual,pleasepay attention to the information summarized here. 

### Program Diskettes. Disk 1 contains the program and the basic data fIles. Disk 2 contains fIles used to carry outthe EPA Multiple Pathways analyses. The user is advised to work initially with the fIles supplied on Diskette 1. 

### Virus Checking. The diskettes have been checked using a commercial product. An additional checkby the user, prior to installation, is recommended. 

### Installation. Create a directory \ERA on a hard disk and copy all the fIles on Diskette 1 to this directory. Itis not necessary to make any path assignments. 

### COMMAND.COM. The

### rootdirectory ofthe diskcontainingthe\ERAdirectory musthave acopy ofCOMMAND.COM, otherwise ERA will not work. 

### README.DOC. Type out or print fIle README.DOC. The me gives important information relating to the computer hardware requirements and to methods ofconfiguring ERA to work with it. 

### SETUP.DAT. This me contains information relating to the default hardware expected by ERA. Mter reading README.DOC (and Section 2 of the manual), make any necessary changes to SETUP.DAT with an ASCn text editor. 

### Ifyou don'tdo so, the program might notworkproperly on your computer. 

### Math Co-Processor. ERAuses someveryintensive calculation methods. Themachine musthave a math co-processor to run ERA. 

### HelpMenus. Extensive Help menus are builtinto ERA at all levels. Press the Fl function key to requestthemenu. Theprogrammanual assumesthattheuseraccessestheHelpmenuas theprimary means ofresolving programdata questions. 

### Starting theProgram. Type ERA and press the <Enter> key.

### Table of Contents

LO INTRODUCTION 1-1 1.1 Background 1-1 1.2 Capabilities and Limitations 1-2 1.3 Microcomputer Requirements 1-2 1.4 How to Read This Manual 1-3 2.0 PROGRAM INSTALLATION 2-1 2.1 Initial Steps 2-1 2.2 Program Data and Execution Files 2-2 2.3 Customizing ERA to Your Computer Environment 2-6 2.4 Solution Tolerances 2-7 2.5 Running ERA 2-7 2.6 Display of Results 2-8 3.0 MODEL OVERVIEW 3-1 3.1 Basic Structure of the ERA Program 3-1 3.2 E.BAT 3-3 3.3 Input Data Processor ( .E ) 3-4 3.4 Cabinet Loads Model (CAB.E ) 3-4 3.5 Refrigeration Cycle Analysis and Energy Use (ERACYC.EXE) 3-5 

### 4.0 DATA INPUT PROCESSOR 4-1 4.1 Menu Structure 4-1 4.2 Retrieving and Saving Input Data Files 4-3 4.3 Data File Management 4-3 4.4 Editing Data 4-5 4.5 Getting Help 4-5 4.6 Default Data 4-9 4.7 Calculation Assists 4-9 4.8 Input Data Error Trapping and Correction 4-11 4.9 Using DOS Within ERA 4-11 4.10 Printing Input Data Files 4-12 4.11 Program Execution 4-12 

### 500 CABINET LOADS INPUT DATA REFERENCE 5-1 5.1 Title of Analysis 5-1 5.2 Cabinet Type and Dimensions 5-1 5.3 Refrigerated Volumes 5-2 5.4 Freezer and Fresh Food Cabinets 5-2 5.5 Mullion 5-4 5.6 Air and Cabinet Temperatures 5-4 5.7 Door Opening Schedules 5-4 5.8 Gasket Heat Leaks 5-5 5.9 Defrost and Controls Energy Use 5-5

i Table of Contents 

### 1.0 INTRODUCTION 1.1 Background 1.2 Capabilities and Limitations 1.3 Microcomputer Requirements 1.4 How to Read This Manual 2.0 PROGRAM INSTALLATION 1·1 1-1 1-2 1-2 1-3 

### 2·1 2.1 Initial Steps 2-1 2.2 Program Data and Execution Files 2-2 2.3 Customizing ERA to Your Computer Environment 2-6 2.4 Solution Tolerances 2-7 2.5 Running ERA 2-7 2.6 Display ofResults 2-8 3.0 MODEL OVERVIEW 3-1 3.1 Basic Structure ofthe ERA Program 3-1 3.2 ERA.BAT 3-3 3.3 Input Data Processor (MENU.EXE) 3-4 3.4 Cabinet Loads Model (CAB.EXE) 3-4 3.5 Refrigeration Cycle Analysis and Energy Use (ERACYC.EXE) 3-5 4.0 DATA INPUT PROCESSOR 4.1 Menu Structure 4.2 Retrieving and Saving Input Data Files 4.3 DataFile Management 4.4 Editing Data 4.5 Getting Help 4.6 Default Data 4.7 Calculation Assists 4.8 Input DataError Trapping and Correction 4.9 Using DOS Within ERA 4.10 Printing Input Data Files 4.11 Program Execution 5.0 CABINET LOADS INPUT DATA REFERENCE 5.1 Title ofAnalysis 5.2 Cabinet Type and Dimensions 5.3 Refrigerated Volumes 5.4 Freezer and Fresh Food Cabinets 5.5 Mullion 5.6 Air and Cabinet Temperatures 5.7 Door Opening Schedules 5.8 Gasket Heat Leaks 5.9 Defrost and Controls Energy Use

1 

### 4·1 4-1 4-3 4-3 4-5 4-5 4-9 4-9 4-11 4-11 

### 4-12 4-12 

### 5·1 5-1 5-1 5-2 5-2 5-4 5-4 5-4 5-5 5-5Table of Contents (Continued) 5.10 Electrical Anti-Sweat Heat 5-5 5.11 Refrigerant Line Anti-Sweat Heat 5-6 5.12 Penetration Heat Input 5-7 

### 6.0 REFRIGERATION CYCLE INPUT DATA REFERENCE 6-1 6.1 Cycle Type 6-1 6.2 Refrigerants 6-2 6.3 Evaporator Design 6-3 6.4 Condenser sign 6-5 6.5 Calculation Assist Menus for Evaporator and Condenser UA Values 6-5 6.6 Compressor Design 6-5 6.7 Cycling Losses 6-7 6.8 Interchangers 6-8 7.0 

### SAMPLE PROBLEM 7-1 7.1 Multiple Pathway "Model D" Prototype Design 7-1 7.2 Input Data Menus (MODEL_D.INP) 7-1 7.3 Intermediate Cabinet Loads Data File (CABINET.DAT) 7-1 7.4 Cabinet Loads Results (CABINET.OUT) 7-13 7.5 Intermediate Cycle Data File (CYCLE.DAT) 7-13 7.6 Cycle Analysis Results (CYCLE.OUT) 7-18 7.7 Energy Consumption Results (ERA.OUT) 7-21 

### 8.0 SUGGESTIONS FOR USING ERA 8-1 8.1 File Naming Conventions 8-1 8.2 Internal Documentation of the Case 8-1 8.3 Summary Output Form 8-2 

### 9.0 REFERENCES 9-1 Appendix A: Overview of Cabinet Loads Analysis Technical Approach A-1 Appendix B: Overview of Cycle Analysis Technical Approach E-1 Appendix C: Sample Data Files: Multiple Pathways Data Input C-1

ii Table of Contents (Continued) 

### 5.10 Electrical Anti-Sweat Heat 5-5 5.11 RefrigerantLine Anti-Sweat Heat 5-6 5.12 Penetration Heat Input 5-7 

### 6.0 REFRIGERATION CYCLE INPUT DATA REFERENCE 

### 6-1 6.1 Cycle Type 6-1 6.2 Refrigerants 6-2 6.3 EvaporatorDesign 6-3 6.4 CondenserDesign 6-5 6.5 Calculation Assist Menus for Evaporator 6-5 and Condenser U A Values 6.6 Compressor Design 6-5 6.7 Cycling Losses 6-7 6.8 Interchangers 6-8 

### 7.0 SAMPLE PROBLEM 

### 7-1 7.1 Multiple Pathway "Model D" Prototype Design 7-1 7.2 Input DataMenus (MODEL_D.lNP) 7-1 7.3 Intermediate Cabinet Loads Data File (CABINET.DAT) 

### 7-1 7.4 Cabinet Loads Results (CABINET.OUT) 7-13 7.5 Intermediate Cycle DataFile (CYCLE.DAT) 7-13 7.6 Cycle Analysis Results (CYCLE.OUT) 7-18 7.7 Energy Consumption Results (ERA.OUT) 7-21 

### 8.0 SUGGESTIONS FOR USING ERA 

### 8-1 8.1 File Naming Conventions 8-1 8.2 Internal Documentation ofthe Case 8-1 8.3 Summary Output Form 8-2 

### 9.0 REFERENCES 

### 9·1 Appendix A: Overview ofCabinet Loads Analysis Technical Approach A-I Appendix B: Overview ofCycle Analysis Technical Approach B-1 Appendix C: Sample DataFiles: Multiple Pathways Data 

### Input C-l

iiList of Figures

Figure No. 3-1 Overall Data and Program Flow 3-2 

### 3-2 J-orenz-Meutzner Refrigerator/Freezer Cycle 3-5 4-1 Main Menu 4-2 

### 4-2 File Selection Menu Example 4-4 4-3 Cycle Data Edit Menu 4-6 4-4 Data Edit Menu Example 4-7 4-5 Help Menu Example 4-8 4-6 Calculation Assist Menu Example 4-10 

### 7-1 Vertical Section - 18Ft3 Prototype Model 7-3 7-2 Front View, Cabinet Only - 18 Ft3 Prototype Model 7-4 7-3 Heat Exchanger Designs 7-5 7-4 Input Data Menus 7-6 7-5 Intermediate Data: Cabinet Loads Analysis 7-11 

### 7-6 Cabinet Loads Output 7-14 7-7 Intermediate Data: Cycle Analysis 7-16 7-8 Cycle Analysis Output 7-19 7-9 Energy Consumption Results 7-22 8-1 Summary Output Form 8-3

111 List of Figures Figure No. 3-1 Overall Data and Program Flow 3-2 3-2 Lorenz-Meutzner Refrigerator!Freezer Cycle 3-5 4-1 Main Menu 4-2 4-2 File Selection Menu Example 4-4 4-3 Cycle Data Edit Menu 4-6 4-4 Data Edit Menu Example 4-7 4-5 Help Menu Example 4-8 4-6 Calculation Assist Menu Example 4-10 7-1 Vertical Section

- 18FePrototype Model 7-3 7-2 Front View, Cabinet Only

- 18 Fe Prototype Model 7-4

I 7-3 Heat Exchanger Designs 7-5 7-4 Input Data Menus 7-6 7-5 Intermediate Data: Cabinet Loads Analysis 7-11 7-6 CabinetLoads Output 7-14 7-7 Intermediate Data: Cycle Analysis 7-16 7-8 Cycle Analysis Output 7-19 7-9 Energy Consumption Results 7-22 8-1 Summary OutputForm 8-3



### iiiList of Tables Table No. 1-1 Refrigerator/Freezer Design/Performance Parameters 1-4 2-1 ERA Data and Execution Files 

### 2-4 7-1 Characteristics of Model D Prototype Refrigerator 7-2

iv List of Tables

Table No. 

### 1-1 2-1 

### 7-1 Refrigerator/Freezer Design/Perfonnance Parameters ERA Data and Execution Files Characteristics ofModel D Prototype Refrigerator

iv 

### 1-4 2-4 7-21.0 I NTRODUCTI ON

1.1 Background Substantial advances have been made in the energy efficiency of refrigerators and freezers in the past four decades since the introduction of CFCs. Prior to concerns overthe environmental impacts of ozone depletion, these fluids were felt to have ideal properties for this application. The ban on the use of these chemicals requires rapid product redesign which must not only eliminate the use of CFCs but also meet tightened energy efficiency standards.Development of improved refrigerators and freezers has been primarily by evolutionary improvement of the product, largely by component design. Because of the simultaneous needs for refrigerant replacement, new foam blowing methods (or alternate insulation concepts) and significant reductions from current energy consumptionlevels, the industry must now look at a wide range of refrigerant possibilities and alternative cycle concepts. Refrigerant options include pure FIFCs, HCFCs, and mixtures of fluids. The EPA Refrigerator Analysis Program (ERA) was designed to enable a comparisonof the performance potential of alternate cabinet and cycle designs of current and nearterm interest. A goal of the program is to allow evaluations of the various design options on a common analytical basis and to enable a consistent means of determining the performance and economic tradeoffs between these options. It is recognized that the use of such a model is only one step towards improving the appliance design. ERA combines an analysis of the refrigeration load requirements of the cabinet with a simulation of the capacity and efficiency of the refrigeration cycle. The cabinet loads programs is an enhancement of a program developed for the U.S. Department ofEnergy during the late 1970s [ 1]. Model enhancements include addition of door opening effects, additional flexibility in describing the cabinet geometry, and an ability to deal with complex insulation systems. The cycle model is a derivative of the NIST CYCLE 7 program [2] which uses the CSD equation of state to represent the thermodynamic properties of pure and mixedrefrigerants [3]. Routines for calculating properties, and refrigerant property coefficients, are similar to those in the REFPROP3 program, available from NIST [4].Changes in the cycle model include 1) incorporation of an ability to deal with refrigerator/freezer cycle design, 2) addition of interchangers, 3) specification of the heat exchanger parameters in terms of its design details, and 4) determination of mass flow and motor power consumption from a compressor model. The refrigerant cycle options added to the model are 1) standard single evaporator refrigerator/freezer, 2) Lorenzcycle with refrigerant mixture, 3) dual-loop system employing two independent refrigeration cycles, one for each compartment, and 4) dual evaporator cycle, with two evaporators connected in series, normally employing a pure refrigerant. 1.0 INTRODUCTION 1.1 Background Substantial advances have been made in the energy efficiency ofrefrigerators and freezers in the past four decades since the introduction ofCFCs. Priorto concerns over the environmental impacts ofozone depletion, these fluids were felt to have ideal properties for this application. The ban on the use ofthese chemicals requires rapid product redesign which must not only eliminate the use ofCFCs but also meet tightened energy efficiency standards. Development ofimprovedrefrigerators and freezers has been primarily by evolutionary improvement ofthe product, largely by component design. Because ofthe simultaneous needs for refrigerant replacement, new foam blowing methods (or alternate insulation concepts) and significantreductions from current energy consumption levels, the industry must now look at a wide range ofrefrigerant possibilities and alternative cycle concepts. Refrigerant options include pure HFCs, HCFCs, and mixtures offluids. The EPA Refrigerator Analysis Program (ERA) was designed to enable a comparison ofthe performance potential ofalternate cabinet and cycle designs ofcurrent and nearterm interest. A goal ofthe program is to allow evaluations ofthe various design options on a common analytical basis and to enable a consistent means ofdetermining the performance andeconomic tradeoffs between these options. It is recognized that the use of such a model is only one step towards improving the appliance design. ERA combines an analysis ofthe refrigeration loadrequirements ofthe cabinet with a simulation ofthe capacity and efficiency ofthe refrigeration cycle. The cabinet loads programs is an enhancement ofa program developed for the U.S. Department of Energy during the late 1970s [1]. Model enhancements include addition ofdoor opening effects, additional flexibility in describing the cabinet geometry, and an ability to deal with complex insulation systems. The cycle model is a derivative ofthe NIST CYCLE 7 program [2] which uses the CSD equation of state to represent the thermodynamic properties ofpure and mixed refrigerants [3]. Routines for calculating properties, andrefrigerant property coefficients, are similar to those in the REFPROP3 program, available from NIST [4]. Changes in the cycle model include 1) incorporation ofan ability to deal with refrigerator/freezer cycle design, 2) addition ofinterchangers, 3) specification ofthe heat exchangerparameters in terms ofits design details, and 4) determination ofmass flow and motor powerconsumption from a compressor model. The refrigerant cycle options added to the model are 1) standard single evaporatorrefrigerator/freezer, 2) Lorenz cycle with refrigerant mixture, 3) dual-loop system employing two independentrefrigeration cycles, one for each compartment, and 4) dual evaporator cycle, with two evaporators connected in series, normally employing a purerefrigerant.

1-11.2 Capabilities and Limitations ERA determines the daily energy projection assuming quasi-steady cabinet heat flow and cycle-averaged operating efficiencies. The underlying assumption is that the effects of cabinet load dynamics and the uncertainties associated with corrections to describe refrigeration system cycling behavior, are small in relation to the difference between alternative cabinet and cycle designs.Most, but not all, of the common refrigerator classes are represented within ERA. Version 1.0 of the program is not capable of directly modelling a single door refrigerator/freezer, such as found in compact units. The program is best thought as a design tool, intended to provide a means of sortingthough the consequences of alternative design concepts and/or component characteristics on potential energy savings. As such, the model calculates what is theoretically possible, not what may be achieved in actual practice. For example, various design approaches may or may not be acceptable from a customer standpoint (e.g., impact onmoisture level control). The refrigerator designer must consider the practicality, potential reliability , and costs of all design options. ERA is a tool that can be used as part of the design process to determine the energy potential performance benefits of a candidate option. Table 1 summarizes the refrigerator/freezer design and performance factors considered by the program. In most instances, the individual heat flow and cycle parameters can be treated on the basis of physical principles. In certain instances basic assumptionsmust be provided by the user (for example, the temperature of the air under the refrigerator cabinet must be specified). In all instances, certain idealizations must be accepted as a starting point for describing the physical or model parameter.For this reason, proper use of the model requires an adequate understanding of its capabilities and inherent limitations. Descriptions of each of the input and output parameters is provided throughout this manual and in the Help menus found in the program. 1.3 Microcomputer Requirements ERA runs in the MS-DOS environment. A minimum computer configuration will include: ® 640 K on-board memory ® 4 Meg hard disk storage available ® math compressor (80X87 chip) Because of the extensive computational requirements for the thermodynamic property determination, it is highly recommended that a 386 or 486 class machine be utilized. Although not required, a color monitor of high resolution is also recommended to takeadvantage of the use of various color attributes by the program as a means of conveying information. 1.2 Capabilities and Limitations ERA determines the daily energy projection assuming quasi-steady cabinet heat flow and cycle-averaged operating efficiencies. The underlying assumption is that the effects ofcabinet load dynamics and the uncertainties associated with corrections to describe refrigeration system cycling behavior, are small in relation to the difference between alternative cabinet and cycle designs. Most, but not all, ofthe common refrigerator classes are represented within ERA. Version 1.0 ofthe program is not capable ofdirectly modelling a single doorrefrigerator/freezer, such as found in compact units. The program is best thought as a design tool, intended to provide a means ofsorting though the consequences ofalternative design concepts and/or component characteristics on potential energy savings. As such, the model calculates what is theoretically possible, not what may be achieved in actual practice. For example, various design approaches mayormay not be acceptable from a customer standpoint (e.g., impact on moisture level control). The refrigerator designer must consider the practicality, potential reliability, and costs ofall design options. ERA is a tool that can be used as part of the design process to determine the energy potential performance benefits ofa candidate option. Table 1 summarizes the refrigerator/freezer design and performance factors considered by the program. In most instances, the individual heat flow and cycle parameters can be treated on the basis ofphysical principles. In certain instances basic assumptions must be provided by the user (for example, the temperature ofthe air under the refrigerator cabinet must be specified). In all instances, certain idealizations must be accepted as a starting point for describing the physical or model parameter. For this reason, proper use ofthe model requires an adequate understanding ofits capabilities and inherent limitations. Descriptions ofeach ofthe input and output parameters is provided throughout this manual and in the Help menus found in the program. 1.3 Microcomputer Requirements ERA runs in the MS-DOS environment. A minimum computerconfiguration will include: " 640 K on-board memory

It 4 Meg hard disk storage available

.. math compressor (80X87 chip) Because ofthe extensive computational requirements for the thermodynamic property determination, 

### itis highly recommended that a 386 or486 class machine be utilized. Although not required, a colormonitor ofhigh resolution is also recommended to take advantage ofthe use ofvarious color attributes by the program as a means ofconveying information.

1-21.4 How to Use this Manual

The structure of this manual attempts to follow the ERA input data processor program to the greatest degree possible. For the user in a hurry, the most important sections toread are: Section 2 (Program Installation), Section 4 (Data Input Processor) and Section 7 (Sample Problem). Various Help Menus within the program are available to provide on-line information as needed. Section 3 (Model Overview) provides a description of the overall structure of ERA and the relationships between the three executable files comprising ERA. Summary discussions of the engineering algorithms used in these sub-programs appear in Appendices A (Cabinet Loads) and B (Cycle Analysis). These sections can be read as required to answer specific questions or to gain a deeper understanding of what ERA can and cannot do. Sections 5 and 6 are reference chapters which define the input data requirements for each data menu in ERA. They supplement material found in the on-line Help Menu. If additional information is desired about an input data, the program user should turn to these sections. Suggestions for file naming conventions and for documenting the program input/output are contained in Section 8. They may prove helpful in managing the large amount of output from making multiple ERA analyses. 1.4 How to Use this Manual 

### The structure ofthis manual attempts to follow the ERA input data processorprogram to the greatest degree possible. Forthe user in a hurry, the most important sections to read are: Section 2 (Program Installation), Section 4 (Data Input Processor) and Section 7 (Sample Problem). Various Help Menus within the program are available to provide on-line infonnation as needed. Section 3 (Model Overview) provides a description ofthe overall structure of ERA and the relationships between the three executable files comprising ERA. Summary discussions ofthe engineering algorithms used in these sub-programs appear in Appendices A (Cabinet Loads) and B (Cycle Analysis). These sections can be read as required to answer specific questions or to gain a deeper understanding ofwhat ERA can and cannot do. Sections 5 and 6 are reference chapters which define the input data requirements for each data menu in ERA. They supplement material found in the on-line Help Menu. If additional infonnation is desired about an input data, the program user should tum to these sections. Suggestions for file naming conventions and for documenting the program input/output are contained in Section 8. They may prove helpful in managing the large amount of output from making multiple ERA analyses.

1-3Table 1-1 Refri 1e.
Category --/Freezer Design/Performance Parameters

Parameter How Treated Cabinet Loads Configurations Top-Mount R/F, Bottom-Mount R/F, Sideby-Side R/F, Chest Freezer, Upright Freezer External Dimensions Internal Dimensions Control Temperatures Ambient Conditions Insulation System - Edge Losses - Construction
- Penetrations Heat Conduction from Environment Internal Heat Conduction Gasket Heat Leaks Heaters Ancillary Heat Input
Mullion and Cabinet Flange Heat Door Openings Effects
Number of doors Moisture - Open Door - Condensation Defrost Specified Calculated Specified for each cabinet section Assumed constant Specify temperature and relative humidity of the environment
Calculated analytically within program Foam, advanced insulation, or composite panels treated User-specified heat leaks Wedge , wall panel , door, top, bottom, back panel, mullion edges Across mullion between compartments Conduction loss related to door perimeter Anti-sweat heaterFan heat determined by compressor runtime; controls heat input considered constant and/or run-time dependent Electric Hot gas from compressor Condenser liquid line Latent and sensible loads Time dependent openings 1 or 2 Calculated moisture input Mass balance, with all moisture condensing Determined from moisture balance and temperature of evaporator. Defrost energy equal to heat of freezing Table 1-1 Refrigerator/Freezer Design/Performance Parameters
category Cabinet Loads Parameter Configurations

External Dimensions Internal Dimensions Control Temperatures
Ambient Conditions
Insulation System

- Edge Losses

- Construction

- Penetrations Heat Conduction from Environment Internal Heat Conduction Gasket Heat Leaks Heaters Ancillary Heat Input

Mullion and Cabinet Flange Heat
Door Openings Effects
Number of doors Moisture

- Open Door

- Condensation Defrost



### 1-4 How Treated Top-Mount RlF, Bottom-Mount RlF, Sideby-Side RlF, Chest Freezer, Upright Freezer Specified Calculated Specified for each cabinet section Assumed constant Specify temperature and relative humidity of the environment

Calculated analytically within program Foam, advanced insulation, or composite panels treated User-specified heat leaks Wedge, wall panel, door, top, bottom, back panel, mullion edges Across mullion between compartments Conduction loss related to door perimeter Anti-sweat heater Fan heat determined by compressor runtime; controls heat input considered constant and/or run-time dependent Electric Hot gas from compressor Condenser liquid line Latent and sensible loads Time dependent openings 10r2
Calculated moisture input Mass balance, with aU moisture condenSing Determined from moisture balance and temperature of evaporator. Defrost energy equal to heat of freezingTable 1-1 F ' _ Drtor/Freezer Design/Performance Parameters (continued)

Refrigeration Cycle Parameter How Treated

Cycle Types

Refrigerants Heat Exchanger Types
Heat Exchange Parameters

Heat Transfer Rates Heat Exchanger Model Pressure Drops Refrigerant Flow Control
Compressor Model

Compressor Design
Details of Compressor Mass Flow Mod el Volumetric Efficiency
Energy Consumptions Cabinet

Cycle Standard ( 1 evap/1 cond) Dual Loop (2 units) Lorenz Cycle Dual evaporator 34 Pure refrigerants Binary or ternary blends Static or fan-forced Cross-flow or counter-flow In-cabinet space or hot-wall/cold-wall Specify or calculate overall U by regime Specify or calculate total area Specify fan air flow Specify fan powersSpecify or calculate. Effect of degradation due to mixtures not considered Effectiveness - NTU Model Specify or calculate Specify subcooling and superheat Independent of refrigerant charge or type of expansion device Built-in model determines power and mass flow. Control options includesingle speed and variable speed. Compressor map option available Single stage reciprocating design or rotary Speed, displacement specified. Suction gas density calculatedDetermined by clearance volume, pressure ratio, temperature. Heaters Defrost Ancillary (lights, controls) Fan Power Compressor power Electronics Table 1-1 Refrigerator/Freezer Design/Performance Parameters (continued) category Parameter How Treated Refrigeration Cycle Cycle Types Standard (1 evap/1 cond) Dual Loop (2 units) Lorenz Cycle Dual evaporator Refrigerants 34 Pure refrigerants Binary or ternary blends Heat Exchanger Types Static or fan-forced Cross-flow or counter-flow In-cabinet space or hot-waillcold-wall Heat Exchange Parame- Specify or calculate overall U by regime tel's Specify or calculate total area Specify fan air flow Specify fan powers Heat Transfer Rates Specify or calculate. Effect of degradation due to mixtures not considered Heat Exchanger Model Effectiveness
- NTU Model Pressure Drops Specify or calculate Refrigerant Flow Control Specify subcooling and superheat Independent of refrigerant charge or type of expansion device Compressor Model Built-in model determines power and mass flow. Control options include single speed and variable speed. Compressor map option available Compressor Design Single stage reciprocating design or rotary Details ofCompressor Mass Flow Speed, displacement specified. Suction Model gas density calculated Volumetric Efficiency Determined by clearance volume, pressure ratio, temperature. Energy Consumptions Cabinet Heaters Defrost Ancillary (lights, controls) Cycle Fan Power Compressor power Electronics



### 1-52.0 PROG RAM INSTALLATION

2.1 Initial Steps ERA uses a simple file structure. All files should be loaded in a single hard-drivedirectory (e.g., \ERA) The root directory of the drive should contain COMMAND.COM. If a virtual drive is set up or if an auxiliary hard-card type drive is used the root directory might not contain COMMAND.COM. The absence of this file in the root directory even if a path is defined to another drive or directory, will result inincomplete operation of ERA, since the program must have access to a secondary command processor for some of its functions. ERA and its files are supplied on a single high-density diskette. The diskette has beenvirus-checked; however, the user should perform a secondary virus check before loading the disk contents onto the hard disk.Program installation consists of the following steps, where it is assumed that the program is to installed on hard drive C: from the program diskette in drive A: Step 1: Create a directory named ERA on the hard drive and then change to the directory. 

### C: SERA CD\ERA Step 2: Copy the contents of the ERA 1 disk to the ERA directory on the hard drive. 

### COPY A: C: Step 3: Create a subdirectory DATA to contain the data files and change to the subdirectory. MD DATA CD DATA Step 4: Copy the data files from the program diskette to the FILES subdirectory. COPY A: *.ERA C:\ERA\DATA ERA is supplied with two additional diskettes that contain the input files created for theEPA Multiple Pathways analysis [5]. The data is grouped according to the refrigerator/freezer

. For example, all pathways starting with Model A refrigerator/freezer are contained in directory \MODEL_A on one of the two data disks. 2.0 PROGRAM INSTALLATION 2.1 Initial Steps ERA uses a simple file structure. All files should be loaded in a single hard-drive directory (e.g.,\ERA) The root directory ofthe drive should contain COMMAND.COM. Ifa virtual drive is set up orifan auxiliary hard-card type drive is used the root directory might not contain COMMAND.COM. The absence ofthis file in the root directory 

### even 

### if apath is defined to another drive ordirectory, will result in incomplete operation ofERA, since the program must have access to a secondary command processorfor some ofits functions. ERA and its files are supplied on a single high-density diskette. The diskette has been virus-checked; however, the user shouldperform a secondary virus check before loading the disk contents onto the hard disk. Program installation consists ofthe following steps, where itis assumed that the program is to installed on hard drive C: from the program diskette in drive A: Step I: Create a directory namedERA on the hard drive and then change to the directory. 

### C: MD\ERA CD\ERA Step 2: Copy the contents ofthe ERA 1 disk to the ERA directory on the hard drive. COpy A:C: Step 3: Create a subdirectory\DATA to contain the data files and change to the subdirectory. MDDATA CD DATA Step 4: Copy the data files from the program diskette to the FILES subdirectory. COpy A:*.ERA C:\ERA\DATA ERA is supplied with two additional diskettes that contain the input files created for the EPA Multiple Pathways analysis [5]. The datais grouped according to the refrigerator/freezer. For example, all pathways starting with Model A refrigerator/freezer are contained in directory\MODEL_A on one ofthe two data disks.

2-1The following DOS commands will create a subdirectory \ E ODEL_A and copy the corresponding files from the data disk:

CD\ERA MODEL_A MODEL_A COPY A : ODEL_A\*.E Similar commands could be used to create subdirectories \E ODEL_B through \ERA ODEL_F and to copy the contents of the two data disks, where it is assumed that the source diskette is in drive A:. Following completion of the file transfers, the supplied diskettes should be stored in a safe place with the write protection tab set. 

### 2.2 Program Data and Execution FilesERA consists of 6 executable files (programs), a batch file (E .BAT), and approximately 80 data files. Most of the data files are either static (not changed by the user) or are modified under the control of an interactive menu - driven input data processor. Several, optional, files are used to control the assumptions used by ERA relating to thecomputer configuration, to control the solution tolerances, or to define compressor performance by a map. Default files are supplied with ERA. They may be modified by using an ASCII editor. Although not required, it is recommended that a full screen scientific (ASCII) editor be utilized with the program. All output is in ASCII form, which can be read with an ASCII editor. In addition, several intermediate files are prepared by the interactive menu-driven processor, as inputs to the executable programs. ERA has been designed to pass data between the various programs using formatted ASCII files to facilitate an understanding of the workings of the program. These intermediate files may be printed out and stored with each run as part of the run documentation. In rare circumstances the user may choose to edit these intermediatedata files directly and execute the cabinet loads (CAB) or cycle performance (ERACYC) program directly. This option is discussed further in Section 3. Table 2.1 lists the files supplied with ERA. A brief discussion of each follows. E RA The overall program and data flow is controlled by this batch file. This file should not be modified. BI,OCKOI.DAT to BLCCK72.DAT. ERA uses 72 data and help menus. They must not be changed. CABINET.DAT. ERA creates this intermediate file as input to the cabinet loads program. Under most circumstances this file is not modified by the user, but is available as an ASCII file describing the input data to the cabinet loads model. CABINET.FRM. This is a static file used to create the intermediate file CABINET.DAT. This file must not be changed.


### 2-2 The following DOS commands will create a subdirectory\ERA \MODEL_A and copy the corresponding files from the data disk: CD\ERA l\ID MODEL_A CD MODEL_A COpy A:\MODEL_A \*.ERA Similarcommands couldbe used to create subdirectories\ERA \MODEL_B through \ERA \MODEL_F andto copy the contents ofthe two data disks, where itis assumed that the source diskette is in drive A:. Following completion ofthe file transfers, the supplied diskettes should be stored in a safe place with the write protection tab set. 2.2 Program Data and Execution Files ERA consists of6 executable files (programs), a batch file (ERA.BAT), and approximately 80 data meso Most ofthe data files are either static (notchanged by the user) or are modified under the control ofan interactive menu - driven input data processor. Several, optional, files are used to control the assumptions used by ERA relating to the computerconfiguration, to control the solution tolerances, orto define compressorperformance by a map. Default files are supplied with ERA. They may be modified by using an ASCII editor. Although notrequired, it is recommended that a full screen scientific (ASCII) editor be utilized with the program. All output is in ASCII form, which can be read with an ASCII editor. In addition, several intermediate files are preparedby the interactive menu-driven processor, as inputs to the executable programs. ERA has been designed to pass data between the various programs using formatted ASCII files to facilitate an understanding ofthe workings ofthe program. These intermediate files may beprinted out and stored with each run as part ofthe run documentation. Inrare circumstances the user may choose to editthese intermediate data files directly and execute the cabinet loads (CAB) or cycle performance (ERACYC) program directly. This option is discussed further in Section 3. Table 2.1 lists the files supplied with ERA. A briefdiscussion ofeach follows. ERABAT. The overall program and data flow is controlled by this batch file. This file should not be modified. BWCKOI,DATto BWCK72,DAT. ERA uses 72 data and help menus. They must not be changed. CABINEI,DAT. ERA creates this intermediate file as input to the cabinet loads program. Under most circumstances this me is not modifiedby the user, but is available as an ASCII me describing the input data to the cabinet loads model. CABINET.FRM. This is a static file used to create the intermediate me CABINET.DA T. This file must not be changed.
2-2*, LMa If the compressor map option is selected , the performance data of the compressor must be defined using a file with this extension . The file is prepared using external editor. A sample file, CO .TAE is supplied. The structure of this file should be evident, and should not be modified. Compressor map files can be prepared for as many compressors as desired, and may be given any legal DOS file name (e.g., ROTARYl.TAE). Ordinarily the na should indicate the compressor type. It is assumed that the compressor map files are stored in the directory containing ERA. CYCLE.DAT. ERA creates this intermediate file as input to the cycle program. Under most circumstances this file is not modified by the user, but is available as an ASCII file describing the input data to the cycle model. CLE.'RM. This is a static file used to create the intermediate file CYCLE.DAT. This file must not be changed. ERAC®ND R and ERACOND.DAT. ERA provides the facility to determine heat transfer rates and pressure drops from various condenser designs . E CO .DAT is an intermediate file prepared by ERA as part of this process. A readable copy of this intermediate file is given by file ERACOND.BAK. Neither of these files should be modified. E EV .R and E EV .DAT. These files are prepared for the evaporator heat transfer and pressure drop analysis. They should not be modified. SETUP.DAT. ERA assumes the presence of a color monitor, and printer port L 1. These assumptions, and other program options, may be changed by editing SETUP.DAT using an external editor. A full discussion of this option is given below (see "Customizing ERA to your Computer Environment"). README.DOC. This file is intended to catch the attention of users who do not take the time to read this Manual. It contains important summary information about ERA. Each ofthe input data files describing the cabinet and cycle design have the extension ERA. The name of the file may have up to 8 characters (e.g., MODEL_D.E ). Creation and modification of these files is done within the ERA menu system. All files are in binary format

. The user must not attempt to edit these files directly since the file structure may be inadvertently changed. CABLM Cabinet loads analyses are performed, using CABINET.DAT as input, under control of the ERA batch command. ERACOND.EXE. Calculation of condenser heat transfer coefficients and pressuredrops is carried out for specified design data. Operation of the program is under control of the ERA Menu-driven data processor. E CYC. EXE. Refrigeration cycle performance and energy use is calculated by this program, which is called by the ERA batch command. ERAEVAP.EXE. Calculation of evaporator heat transfer coefficients and pressure drops is carried out for specified design data

. Operation of the program is under control of the ERA menu

-driven data processor.


### 2-3 

## *

IT



### AB. Ifthe compressor map option is selected, the performance data ofthe compressor must be defined using a file with this extension. The file is prepared using an external editor. A sample file, COMPMAP.TAB is supplied. The structure ofthis file should be evident, and should not be modified. Compressor map files can be prepared for as many compressors as desired, andmay be given any legal DOS file name (e.g., ROTARYl.TAB). Ordinarily the name should indicate the compressor type. It is assumed that the compressor map files are stored in the directory containing ERA. CYCLEDAT, 

### ERA creates this intermediate file as input to the cycle program. Under most circumstances this file is not modified by the user, but is available as an ASCII file describing the input data to the cycle model. CYCLE.FRM, 

### This is a static file used to create the intermediate file CYCLE.DAT. This file must not be changed. ERACOND.BAK 

### and ERACONDDAT. 

### ERA provides the facility to determine heat transferrates and pressure drops from various condenserdesigns. ERACOND.DAT is an intermediate file prepared by ERA as part ofthis process. A readable copy ofthis intermediate file is given by file ERACOND.BAK. Neither ofthese files should be modified. ERAEV AP.BAK

### and ERAEV APDAT. 

### These files are prepared for the evaporator heat transfer and pressure drop analysis. They should not be modified. SETUPDAT. 

### ERA assumes the presence ofa color monitor, and printer port LPTI. These assumptions, and otherprogram options, may be changed by editing SETUP.DAT using an external editor. A full discussion ofthis option is given below (see "CustomizingERA to your ComputerEnvironment"). READMEDOC. 

### This file is intended to catch the attention ofusers who do not take the time to read this Manual. It contains important summary information about ERA. 

# * .ERA. 

### Each ofthe input data files describing the cabinet andcycle design have the extension .ERA. The name ofthe file may have up to 8 characters (e.g., MODEL_D.ERA). Creation and modification ofthese files is done within the ERA menu system. All files are in binary formal The user must not attempt to edit these files directly since the file structure may be inadvertently changed. CAB.EXE. 

### Cabinet loads analyses are performed, using CABINET.DAT as input, under control ofthe ERA batch command. ERACOND.EXE. 

### Calculation ofcondenser heat transfer coefficients andpressure drops is carried outfor specified design data. Operation ofthe program is under control ofthe ERA Menu-driven data processor. ERACyc.EXE. 

### Refrigeration cycle performance and energy use is calculated by this program, which is called by the ERA batch command. ERAEV AP.EXE. 

### Calculation ofevaporatorheat transfer coefficients andpressure drops is carried outfor specified design data. Operation ofthe program is under control ofthe ERA menu-driven data processor. 2-3

### ER -, F; nd Execution Sues



### ERAZAT Batch file that controls processing of input data ASCII

and program execution
BLOCK011MAT Data menus and Help menus (72) Binary 

### to and BLOCK 72MAT ASCII 

### C I ET. T Intermediate file, input to cabinet loads program ASCII
C I ET.F 

### Template for input data to cabinet loads program ASCII
*.TAB 

### Compressor map files ASCII
CYCLE. AT 

### Intermediate file, input to cycle program ASCII
CYCLE.FRM Template for input data to cycle program ASCII
E C . AT° Intermediate file, input to condenser heat ASCII E AC . AK 

### exchanger analysis program ERAEVAPMAT Intermediate file, input to evaporator heat ASCII ERAEVAP.BAK exchanger analysis program SETUP. AT Configuration data. Used to select options for ASCII

ERA READMEMOC Notes on ERA. Documentation file ASCII 

### *.ERA Input data files (see Appendix C) Binary CAB.EXE Cabinet loads analysis program Binary E AC .EXE Condenser heat exchanger analysis program Binary ERACYC.EXE Cycle analysis program and energy use calcula- Binary

tion ERAEVAP.EXE Evaporator heat exchanger analysis program Binary Table 2.1 ERA Data and Execution Flies

ERA,BAT

BLOCK01.DAT to BLOCK 72.DAT CABINET.DAT CABINET.FRM *.TAB CYCLE.DAT CYCLE.FRM ERACOND.DAT ERACOND.BAK ERAEVAP.DAT ERAEVAP.BAK SETUP.DAT

README.DOC ".ERA CAB.EXE ERACOND.EXE ERACYC.EXE

ERAEVAP.EXE Batch file that controls processing of input data ASCII and program execution Data menus and Help menus (72) Binary and ASCII Intermediate file, input to cabinet loads program ASCii Template for input data to cabinet loads program ASCII Compressor map files ASCII Intermediate file, input to cycle program ASCII Template for input data to cycle program ASCII Intermediate file, input to condenser heat ASCii exchanger analysis program Intermediate file, input to evaporator heat ASCII exchanger analysis program Configuration data. Used to select options for ASCII ERA Notes on ERA. Documentation file ASCII Input data files (see Appendix C) Binary Cabinet loads analysis program Binary Condenser heat exchanger analysis program Binary Cycle analysis program and energy use calcula- Binary tion Evaporator heat exchanger analysis program Binary

2-4Tale 2.1 ERA and Execution Files (continued)

MENU.EXE Input data processor Binary S E .E Automated program output display Binary
*.FIG Drawings of cycles (4) Binary *.P RP Thermophysical proprietary data files (7) ASCII CYCLE.TOL Optional file for specifying solution tolerances ASCII
SUMMARY Blank form for summarizing results of analysis. ASCII

Notes: Files, SETUP.DAT, CYCLE.TOL, and *.TAB may be changed using an external ASCII editor. They are read by the executable files (program).
The intermediate files CABINET.DAT and CYCLE.DAT are prepared by ERA. Normally they should not be changed by the user

. However, if desired they may beedited by an external editor and the corresponding files (CAB.EXE and ERACYC.EXE) run separately. Table 2.1 ERA Data and Execution Flies (continued)

MENU.EXE Input data processor Binary SHOWERA.EXE Automated program output display Binary *.FIG Drawings of cycles (4) Binary *.PRP Thermophysical proprietary data files (7) ASCII CYClE.TOl Optional file for specifying solution tolerances ASCII SUMMARY Blank form for summarizing results of analysis. ASCII

Notes: Files, SETUP.DAT, CYCLE.TOL, and *.TAB may be changed using an external ASCII editor. They are read by the executable f:tles (program).
The intermediate f:tles CABINET.DAT and CYCLE.DAT are preparedby ERA. Normally they should not be changed by the user. However, ifdesired they may be edited by an external editor andthe corresponding f:tles (CAB.EXE andERACYC.EXE) run separately.



### 2-5MENfL.E% E. ERA processes all input data through a menu

-driven, interaction program. prepares the input files for subsequent cabinet loads and cycle analyses. SHAH ERA.EXE. Display summary results for cabinet loads and daily energy consumption. ERA.BAT calls SHOWERA at the completion of the cycle analysis. * FI Sketches of the refrigeration cycles are contained within these four files, which are used by the cycle analysis program. They must not be modified. *,89P. Tables of thermophysical properties are available for CFC-12, HCFC-22, C- 152a, HC-270 (cyclopropane), HC-290 (propane) and C-134a in these files. They are used in the analysis of evaporator and condenser heat transfer and pressure drops. ERA will estimate the properties of other refrigerants, or refrigerant mixtures, and store them in file REFRIG.PRP. These files must not be modified. CYCLE. ? ®L. Solution tolerances are contained in this file , which may be modified using an external ASCII editor

. The structure of the file is self-explanatory. Additional information in given below (" Solution tolerances"). SUMMARY. A blank form is provided to summarize the results of the analysis. If desired, this form may be modified with an external editor. Copies of the form are obtained by multiple print outs of the file. 

### 2.3 Customizing ERA to Your Computer EnvironmentERA assumes the following: 1) presence of a color monitor, 2) print output sent to parallel print port LPT1:, 3) data limits within the program must be obeyed, 4) a page eject will not be sent at the beginning of an output file (only at the end), 5) ASCII character 12 serves as the form feed character, and 6) the ERA data files (*.ERA) are contained in directory \ERA. To change these assumptions, a file SETUP.DAT must be present. A sample of this file is shown below:

mono screen=no print_port=lptl form-feed=no page_feed=no i ore limits=no path=\ERAATA If your computer setup does not include a color graphics monitor, then change the command in SETUP

.DAT to read "mono-screen=yes". The program assumes that the printer is connected to LPT1 (or to a COM port using the MODE L1:=C®M? command in the autoexec file). If the printer is connected to LPT2, insert a line reading "print

_port=lpt2" into the SETUP.DAT file (the program is supplied with a default setting of "print

_port=lptl"). Depending upon the printer setup, page ejects are controlled by issuing a "1" or a form feed character (ASCII character 12) in column one. ERA assumes that all files written to a disk use ASCII character 12 for print control, and that those written directly to a printer also use this character . To Utilize "1" in column 1 as the print form feed charac
### 2-6 MENU.EXE. ERA processes aU input data through a menu-driven, interaction program. MENU prepares the input files for subsequent cabinet loads and cycle analyses. SHOWERA.EXE. Display summary results for cabinet loads and daily energy consumption. ERA.BAT calls SHOWERA at the completion ofthe cycle analysis. 

## *

.FIG. Sketches ofthe refrigeration cycles are contained within these four files, which are used by the cycle analysis program. They must not be modified. *.PRP. Tables ofthermophysical properties are available for CFC-12, HCFC-22, HFC-152a, HC-270 (cyclopropane), HC-290 (propane) andHFC-134a in these files. They are used in the analysis ofevaporator and condenser heat transfer and pressure drops. ERA will estimate the properties ofotherrefrigerants, orrefrigerant mixtures, and store them in file REFRIG.PRP. These files must not be modified. CYCLE.TOL. Solution tolerances are containedin this file, which may be modified using an external ASCII editor. The structure ofthe file is self-explanatory. Additional information in given below ("Solution tolerances"). SUMMARY. A blank form is provided to summarize the results ofthe analysis. If desired, this form may be modified with an external editor. Copies ofthe form are obtained by multiple print outs ofthe file. 2.3 Customizing ERA to Your Computer Environment ERA assumes the following: 1) presence ofa color monitor, 2) print output sent to parallel print port LPTl:, 3) data limits within the program mustbe obeyed, 4) a page eject will not be sent at the beginning ofan output file (only at the end), 5) ASCII character 12 serves as the form feed character, and 6) the ERA data files (*.ERA) are contained in directory\ERA. To change these assumptions, a file SETUP.DAT must be present. A sample ofthis file is shown below:



### mono screen=no print port=lptl form-feed=no page**~feed=no** 

### ignore _limits=no path=\ERA \DATA Ifyour computer setup does not include a color graphics monitor, then change the command in SETUP.DAT to read "mono_screen=yes". The program assumes that the printer is connectedto LPT1 (or to a COMport using the MODE LPTl:=COM? command in the autoexec file). Ifthe printeris connected to LPT2, insert a line reading "prinCport=lpt2" into the SETUP.DAT file (the program is supplied with a default setting of "prinCport=lptl"). Depending upon the printer setup, page ejects are controlled by issuing a "1" or a form feed character (ASCII character 12) in column one. ERA assumes that all files written to a disk use ASCII character 12 for print control, and that those written directly to a printer also use this character. To Utilize "1" in column 1 as the print form feed charac2-6ter insert a line reading "form_feed=yes" into the SETUP.DAT file. To issue a page

eject prior to the printout of the first data file enter the command "page_feed=yes" in SE P.DAT. Every data value entered into ERA is checked against upper and lower limits to prevent running a problem with obvious errors. However, in some instances the user may wish to over-ride this capability to force the program to look at some unusual conditions. To allow the program to attempt to run for all data values supplied, enter the command "ignore-limits=yes" in the SE P.DAT file. The user should note that the program may not work for all data values entered. It is assumed that the data files (which have extension ERA) are on the same directory as the program. However, the user may define a path towards another directory or drive where the data files are kept. This is accomplished by inserting the "path=" directive followed by the drive and directory. The example shown above assumes that the files are on the C: drive in sub directory \ERA\DATA. In order for the command to work, it must be left justified in the SETUP.DAT file. If it is not present, ERA will assume all files are found in the directory containing ERA. Two additional statements appear at the end of the SETUP.DAT file supplied with the program: "expand" and "shadow." These commands control the display of the program title screen. With both present, the title ERA is shown using an exploding windowing method and appears to cast a shadow on the screen. These effects can be removed, if desired, by eliminating these last two commands in SE P.DAT. 2.4 Solution Tolerances Because of the many, highly non-linear equations utilized to describe the refrigerator cycle, an iterative solution technique is employed. That is, sets of equations are solved sequentially until the differences between two succeeding solutions fall within some tolerance. The first five data lines in CYCLE.TOL relate to solution for refrigerant temperatures and mass flow. Of these, the most sensitive are the condenser temperature tolerances (set to 0

.01F) and the mass flow rate tolerance (set to 0

.001). The user may wish toexperiment with different values for these tolerances to determine an acceptable tradeoff between computer execution time and refrigerator cycle performance prediction. The program is capable of dividing the two

-phase heat transfer region in the evaporator or condenser into an arbitrary number of nodes. In most instances the choice of only one node will yield nearly the same predicted cycle performance as the choice of 5 or 10 nodes

. To speed computation it is recommended that the specified number of subdivisions remain at one

. In unusual cases, where a refrigerant blend is used which has a highly non

-linear relationship between temperature and quality over the evaporation or condensation process, a larger number of subdivisions can be used (3 is recommended). 2.5 Running ERA To run the program type ERA and press the <Enter> key.

2-7 ter insert a line reading "fonn_feed=yes" into the SETUP.DAT file. To issue a page eject prior to the printout of the first data file enter the command "page_feed=yes" in SETUP.DAT. Every data value enteredinto ERA is checked against upper and lower limits to prevent running a problem with obvious errors. However, in some instances the user may wish to over-ride this capability to force the program to look at some unusual conditions. To allow the program to attempt to run for all data values supplied, enter the command "ignore_limits=yes" in the SETUP.DAT file. The user should note that the program may not work for all data values entered. It is assumed that the data files (which have extension .ERA) are on the same directory as the program. However, the user may define a path towards another directory or drive where the data files are kept. This is accomplished by inserting the "path=" directive followed by the drive and directory. The example shown above assumes that the files are on the C: drive in subdirectory\ERA \DATA. In orderfor the commandto work, itmust be leftjustified in the SETUP.DAT file. If

### it is not present, ERA will assume all files are found in the directory containing ERA. Two additional statements appear at the end ofthe SETUP.DAT file supplied with the program: "expand" and "shadow." These commands control the display ofthe program title screen. With both present, the title ERA is shown using an exploding windowing method and appears to cast a shadow on the screen. These effects can be removed, if desired, by eliminating these last two commands in SETUP.DAT. 2.4 Solution Tolerances Because ofthe many, highly non-linear equations utilized to describe the refrigerator cycle, an iterative solution technique is employed. That is, sets ofequations are solved sequentially until the differences between two succeeding solutions fall within some tolerance. The first five data lines in CYCLE.TaLrelate to solution for refrigerant temperatures and mass flow. Ofthese, the most sensitive are the condenser temperature tolerances (set to 0.01F) and the mass flow rate tolerance (set to 0.001). The user may wish to experiment with different values for these tolerances to detennine an acceptable tradeoffbetween computerexecution time and refrigerator cycle performance prediction. The program is capable ofdividing the two-phase heat transfer region in the evaporator orcondenser into an arbitrary number ofnodes. In most instances the choice ofonly one node will yield nearly the same predicted cycle perfonnance as the choice of5 or 10 nodes. To speedcomputation it is recommended that the specified number of subdivisions remain at one. In unusual cases, where a refrigerant blend is used which has a highly non-linearrelationship between temperature and quality over the evaporation or condensation process, a larger number of subdivisions can be used (3 is recommended). 2.5 Running ERA Torun the program type ERA and press the <Enter> key.

2-72.6 Display of Results Following completion of an analysis under control of the ERA batch command, an automatic display of the results will occur. If a complete analysis is done, including the cycle and energy calculations, the summary results for cabinet loads and daily energy consumption are displayed; if a only a cabinet loads analysis has been requested the cabinet loads output will be displayed. Ordinarily, three output files are available for display: 1) the summary output (ERA.- OUT); 2) the cabinet loads output (CABI T.OU T)); and 3) the cycle analysis results (CYCLE.OUT). Any of these may be requested during the output display by pressingthe <Fl> key (summary output), <F2> key (cabinet loads), or the <F3> key (cycle output). If only a cabinet loads analysis has been requested, the only available output will be the calculated cabinet loads. Request of another output from within execution of the display program, will cause a return to DOS with an error message. A print of any of the files displayed may be requested by simultaneously pressing the <Alt> and <P> keys. It is assumed that the print port is LPT1:. To return to the menu program and perform another analysis press the <FlO> key. To make a normal return to DOS from the display of the output results press the <Esc> key. 2.6 Display of Results Following completion ofan analysis under control ofthe ERA batch command, an automatic display ofthe results will occur. If a complete analysis is done, including the cycle andenergy calculations, the summary results for cabinet loads and daily energy consumption are displayed; ifa only a cabinet loads analysis has been requested the cabinet loads output will be displayed. Ordinarily, three outputfiles are available for display: 1) the summary output (ERA.- OUT); 2) the cabinet loads output (CABINET.OUT); and 3) the cycle analysis results (CYCLE.OUT). Any ofthese may be requested during the output display by pressing the <FI> key (summary output), <F2> key (cabinet loads), or the <F3> key (cycle output). Ifonly a cabinet loads analysis has been requested, the only available output will be the calculatedcabinetloads. Request ofanother output from within execution ofthe display program, will cause a return to DOS with an error message. A print ofany ofthe files displayed may be requested by simultaneously pressing the <Alt> and <I» keys. It is assumed that the printport is LPTI:. To return to the menu program andperform another analysis press the <FlO> key. To make a normal return to DOS from the display ofthe output results press the <Esc> key.

2-83.0 MODEL OVERVIEW

3.1 Basic Structure of the ERA Program ERA consists of a batch command file (E .EAT'), and three major modules:® MENU - a menu driven interaction input processor and analysis flow control prograrn. The program interacts with the user during the program input sification phase and prepares the data files needed for the subsequent program modules;® CAB - analyses of the cabinet loads. The steady-state heat inputs to the cabinet section are determined for various types of refrigerator/freezers, alternative insulation system designs, and specified environment and usage conditions; ® ERACYC - determination of the steady-state, instantaneous, refrigeration cycle capacity and power draws. The hourly average cabinet loads and instantaneous refrigeration capacities determine the compressor duty cycle and the corresponding fan powers. Corrections are made to the compressor energy to account for cyclingeffects. ERACYC establishes the net duty energy consumption and prepares a summary of the results. Data input to both the cabinet loads and cycle models are in the form of ASCII files that can be edited off-line from the main calculation stream if desired. The overall data and program flow is illustrated in Figure 3-1. The program is under the control of the batch file ERA.BAT. Operations specified by ERA.BAT will depend upon choices selected by the user from the Main Menu of the overall control program, MENU. However, because of the modularity of the program structure, and the designof the intermediate files, the program user can elect to run only a portion of the analysis, either from the menu driven program, or external to it using a data editor. Figure 3-1 differentiates these different types of files: program (executable files), data(output from one or more programs which serve as input to another program), and output (given the extension .OUT). The cycle data intermediate file, CYCLE.DAT, receives cycle parameters from the menu program, and has a summary of the cabinet loads results added at the end. The cabinet loads are used by ERACYC to determine the compressor and fan run times. Operation of the heat exchanger analysis programs, ERACOND and ERAEVAP, is completely under the control of the menu program. MENU prepares the required input data, calls the executable files using a secondary command processor, reads the output files, and updates the heat exchanger data values (UA, area, pressure drop).Following completion of an analysis, the ERA batch command calls a file display program (SHOWERA.EXE). Any of the three output files (E .OUT, CABINET.OUT, CYCLE.OUT) may be selected within the display program by pressing a function key. In addition, a return to the menu program for another analysis can be requested by pressing a function key. 3.0 MODEL OVERVIEW 

### 3.1 Basic Structure of the ERA 

### Program ERA consists ofa batch command file (ERA.BAT), and three major modules:

e 

### MENU - a menu driven interaction input processor and analysis flow control program. The program interacts with the user during the program input specification phase and prepares the data files needed for the subsequent program modules;

.. CAB

- analyses ofthe cabinet loads. The steady-state heat inputs to the cabinet section are detenninedfor various types ofrefrigerator/freezers, alternative insulation system designs, and specifiedenvironment and usage conditions;

e 

### ERACYC

- determination ofthe steady-state, instantaneous, refrigeration cycle capacity and power draws. The hourly average cabinet loads and instantaneous refrigeration capacities detennine the compressor duty cycle and the corresponding fan powers. Corrections are made to the compressor energy to account for cycling effects. ERACYC establishes the net duty energy consumption and prepares a summary ofthe results. Data input to both the cabinet loads and cycle models are in the fonn ofASCn files that can be edited off-line from the main calculation stream ifdesired. The overall data andprogram flow is illustrated in Figure 3-1. The program is under the control ofthe batch file ERA.BAT. Operations specified by ERA.BAT will depend upon choices selectedby the user from the Main Menu ofthe overall control program, MENU. However, because ofthe modularity ofthe program structure, and the design ofthe intermediate files, the program user can elect to run only a portion ofthe analysis, either from the menu driven program, or external to it using a data editor. Figure 3-1 differentiates these different types offiles: program (executable files), data (output from one ormore programs which serve as input to another program), and output (given the extension .OUT). The cycle data intermediate file, CYCLE.DAT, receives cycle parameters from the menu program, and has a summary ofthe cabinet loads results added at the end. The cabinet loads are used by ERACYC to determine the compressor and fan run times. Operation ofthe heatexchanger analysis programs, ERACOND and ERAEVAP, is completely under the control ofthe menu program. MENU prepares the required input data, calls the executable files using a secondary commandprocessor, reads the output files, and updates the heat exchanger data values (VA, area, pressure drop). Following completion ofan analysis, the ERA batch commandcalls a file display program (SHOWERA.EXE). Any ofthe three outputfiles (ERA.OUT, CABINET.OUT, CYCLE.OUT) may be selected within the display program by pressing a function key. In addition, a return to the menu program for another analysis can be requested by pressing a function key.

3-1E A. T

MENU.EXE

CYCLE.DAT ® Cycle Parameters ® Cabinet Loads Program

o Process Input Data o Analyze Heat Exc. o Prepare Cycle Data o Prepare Cabinet Data

Data Program

ERACYC.EXE

* Cycle Performance o Energy Use o Process Output Files

Display SHO ERA.EXE

o ERA.OUT o CA INET.OUT o CYCLE.OUT



### Figure 3®1: Overall Data and Program Flow Program ER?, EV '.EYE ERA Cc: J.EXE

Data CAINET.DAT

Outpu Output Results: CAI ET.OUT

Output Output Results: CYCLE.OUT ERA.OUT CYCLE.DAT
" Cycle Parameters " Cabinet Loads Data



# - ERA.BAT

Program MENU.EXE

II Process Input Data

II Analyze Heat Exchanger

II Prepare Cycle Data

II Prepare Cabinet Data

Progl'llllll CAB.EXE

II Calculate Cabinet Loads

II Add Loads to Cycle Data

ERACYC.EXE

II Cycle Performance

II Energy Us. Progl'llllll

II Process Outpu,t Files

SHOWERA.EXE

II ERA.OUT " CABINET.OUT " CYCLE.OUT DIsplay



### Figure 3-1: Overall Data and Program Flow

3-2 Program ERA EVAP.EXE ERA COND.EXE

Data CABINET.DAT

Output Output Results: CABINET.OUT

Output Output Results:

CYCLE.OUT

ERA.OUT3.2 T

As illustrated in Figure 3-1, the overall data and program execution flow is controlled by the ERA batch file. The file is reproduced below:

@Echo off :START if exist cabinet

.dat erase cabinet.dat if exist cycle.dat erase cycle.dat if exist era

.out erase era.out 

### NU if not exist cabinet.dat goto DO NE CAB if not exist cycle

.dat goto SHOW-CAB ERACYC if not exist era.out goto done goto SHOW-ERA :DISPLAY if errorlevel 5 goto NO-FILE if errorlevel 4 goto START if errorlevel 3 goto SHOW-CYCLE if errorlevel 2 goto SHOW-CAB if errorlevel 1 goto SHOW-ERA goto DONE :NO-FILE cis echo Requested File is not Present goto STOP :SHOW CYCLE showera cycle.out goto DISPLAY :SHOW CAB showera cabinet.out goto DISPLAY :SHOW ERA showera era.out goto DISPLAY :DONE cis :STOP echo on The analysis programs (CAB and ERACYC) will be executed only if the intermediate data files (CABINET.DAT and CYCLE.DAT) have been prepared by MENU. 3.2 ERA.BAT As illustrated in Figure 3-1, the overall data and program execution flow is controlled by the ERA batch file. The file is reproduced below:

@Echooff :START ifexist cabinet.dat erase cabinet.dat ifexist cycle.dat erase cycle.dat ifexist era.out erase era.out MENU ifnot exist cabinet.dat goto DONE CAB ifnot exist cycle.dat goto SHOW_CAB ERACYC ifnot exist era.out goto done goto SHOW_ERA :DISPLAY iferrorleve15 gOlo NO_FILE iferrorleve14 gOlO START iferrorlevel 

### 3 goto SHOW_CYCLE iferrorleve12 goto SHOW_CAB iferrorlevel 1goto SHOW_ERA gotoDONE :NO_FILE cls echo RequestedFile is not Present goto STOP :SHOW _CYCLE showeracycle.out goto DISPLAY :SHOW_CAB showera cabinet.out goto DISPLAY :SHOW_ERA showeraera.out goto DISPLAY : DONE cls :STOP echo on The analysis programs (CAB and ERACYC) will be executed only ifthe intermediate data files (CABINET.DAT and CYCLE.DAT) have been prepared by MENU.



### 3-33.3 Input Data Processor ( E U.EX ) allows the following basic options: 1) retrieve and edit the cabinet loads input data, 2) retrieve and edit the refrigeration cycle data, 3) delete a data file, 4) write out the data input file in readable form to a file or directly to the printer, 5) run the cabinet loads program only, and 6) run both the cabinet loads and cycle models and determine the total daily energy consumption and load components. Every menu has associated Help menu. A logical tree sc e is utilized to groupthe data and to provide a means of specifying the data in a fashion similar to the evolution of the overall design. Every data value is screened to ensure that it lies within an allowable range and to guarantee logical consistency with other data. Data specification help routines are available for: 1) determination of the net resistivity of an insulation panel, 2) calculation of evaporator and condenser heat exchanger parameters and pressure drops, and 3) calculation of variable speed fan air flow and fan energy. Input data to the MENU program is a user selected ERA data file. The output files from MENU are CABINET.DAT and CYCLE.DAT. 3.4 Cabinet Loads Model (CAB.EXE)Five basic R/F configurations are described: 1) top-mount refrigerator/freezer, 2) sideby-side refrigerator/freezer, 3) bottom-mount refrigerator/freezer, 4) chest freezer, and 5) upright freezer. Design parameters considered are: external dimensions, internalvolumes, insulation system geometry and resistivities, mullion dimensions and resistivity, compressor cabinet dimensions and insulation design, gasket heat leaks, cabinet section control temperatures, environmental conditions, door opening schedules, and ancillary electrical energies. The cabinet loads program breaks down the steady-state heat loads by component as well as by compartment. Note that the fan heat inputs are not yet considered in the thermal loads budget. They are treated as a correction to the refrigeration capacity, by the cycle program, and are related to the compressor run time. The major heat flows present in the cabinet are considered, including the effects of edge losses associated with vacuum insulation panels. The most significant uncertainties in the modeled loads are associated with the gaskets (conduction and an unknown infiltration), penetrations of the insulation system, and moisture input. A door opening model has been included. Based on some limited research data [7] and a simple description of time-dependent air exchanges, both the sensible and latent heat loads are estimated for user-specified door opening schedules. The moisture exchange may result in additional defrost loads, depending on the temperature of the evaporator. 3.3 Input Data Processor (MENU.EXE) MENU allows the following basic options: 1) retrieve andedit the cabinet loads input data, 2) retrieve and edit the refrigeration cycle data, 3) delete a data file, 4) write out the data input file in readable form to a file ordirecdy to the printer, 5) run the cabinet loads program only, and 6) run both the cabinet loads and cycle models and determine the total daily energy consumption and load components. Every menu has an associated Help menu. A logical tree structure is utilized to group the data and to provide a means ofspecifying the data in a fashion similar to the evolution ofthe overall design. Every data value is screened to ensure that it lies within an allowable range and

## to guarantee logical consistency with other data. Data specification help routines are available for: 1) determination ofthe netresistivity ofan insulation panel, 2) calculation ofevaporator and condenserheat exchanger parameters andpressure drops, and 3) calculation ofvariable speed fan airflow and fan energy. Input data to the MENU program is a user selected .ERA data file. The output files from MENU are CABINET.DAT and CYCLE.DAT. 3.4 Cabinet Loads Model (CAB.EXE) Five basic 

### R/F configurations are described: 1) top-mountrefrigerator/freezer, 2) sideby-side refrigerator/freezer, 3) bottom-mount refrigerator/freezer, 4) chestfreezer, and 5) upright freezer. Designparameters considered are: external dimensions, internal volumes, insulation system geometry and resistivities, mullion dimensions and resistivity, compressor cabinet dimensions and insulation design, gasket heat leaks, cabinet section control temperatures, environmental conditions, door opening schedules, and ancillary electrical energies. The cabinet loads program breaks down the steady-state heat loads by component as well as by compartment. Note that the fan heat inputs are not yet considered in the thermal loads budget. They are treated as a correction to the refrigeration capacity, by the cycle program, and are related to the compressorrun time. The major heat flows present in the cabinet are considered, including the effects ofedge losses associated with vacuum insulationpanels. Themost significantuncertainties in the modeledloads are associated with the gaskets (conduction and

# an unknown infIltration), penetrations ofthe insulation system, and moisture input. A door opening model has been included. Based on some limited research data [7] and a simple description oftime-dependent air exchanges, both the sensible and latent heat loads are estimated for user-specified door opening schedules. The moisture exchange may result in additional defrost loads, depending on the temperature ofthe evaporator.

3-4

### 3.5 Refrigeration Cycle Analysis and Energy Use (ERACYC.EXE)

Four cycle configurations are descri : 1) standard single evaporator refrigerator/freezer, 2) Lorenz cycle with refrigerant mixtures, 3) dual-loop system employing two independent refrigeration cycles, one for each compartment, and 4) dual evaporator cycle, with two evaporators connected in series, normally employing a pure refrigerant. Figure 3-2 illustrates one of the cycles (Lorenz) described by ERA. ERACYC will establish the refrigerant pressures and enthalpies around the cycle and the mass flow that satisfies the heat and mass balances at each location in the cycle. Note that the single evaporator cycle and dual evaporator cycle are derivatives of the Lorenz cycle.

9

MM

m Tmnp

Figure 3-2. Lorenz-Meutzner Refrigerator/Freezer Cycle

The following control methods are adopted by the program: ® Standard Single Evaporator Cycle - The fresh food section and freezer sectiontemperatures are specified. Air damper control is assumed to achieve these temperatures. The analysis involves calculation of the temperature of the air mixing from the two compartments as it approaches the evaporator. For example, if cabinet temperatures of 38F and 5F are specified for the two compartments, the mixed air temperature inlet to the evaporator will be about 12F, depending on the ratio of the cabinet loads and the evaporator refrigerant temperature. 3.5 Refrigeration Cycle Analysis and Energy Use (ERACYC.EXE) Fourcycle configurations are described: 1) standard single evaporatorrefrigerator/freezer, 2) Lorenz cycle with refrigerant mixtures, 3) dual-loop system employing two independentrefrigeration cycles, one for each compartment, and 4) dual evaporator cycle, with two evaporators connected in series, normally employing a pure refrigerant. Figure 3-2 illustrates one ofthe cycles (Lorenz) described by ERA. ERACYC will establish the refrigerant pressures and enthalpies around the cycle and the mass flow that satisfies the heat and mass balances at each location in the cycle. Note that the single evaporator cycle and dual evaporator cycle are derivatives ofthe Lorenz cycle.

2

Temp

Figure 3-2. Lorenz-Meutzner Refrigerator/Freezer Cycle

The fonowing control methods are adopted by the program: Standard Single Evaporator Cycle

- The fresh food section and freezer section temperatures are specified. Airdamper control is assumed to achieve these temperatures. The analysis involves calculation ofthe temperature ofthe air mixing from the two compartments as itapproaches the evaporator. Forexample, ifcabinet temperatures of38F and 5F are specified for the two compartments, the mixed air temperature inlet to the evaporator will be about 12F, depending on the ratio ofthe cabinet loads and the evaporatorrefrigerant temperature.

3-5® Dual Loop Cycle - Each refrigeration loop, which contains its own evaporator,compressor, and condenser, acts independently to achieve the average temperatures specified for the individual compartments. The model simulates each l oop separately. ® Lorenz Cycle - The air temperatures approaching the two evaporators are assumedto be at the specified control points. Normally the evaporator loads will be unbalanced, requiring additional refrigeration to be delivered to one of the compartments during off-cycle period for the other compartment. The control options are: 1) adjust the fresh food section temperat ; 2) adjust the freezer temperature; 3) adjust the evaporator areas; 4) use a means to bypass the refrigerant cooling of one evaporators during a portion of the cycle to enable the other evaporator to meet its cabinet load; 5) allow imbalance to occur. Control option 4 is intended to represent the use of a solenoid valve for refrigerant bypass, or the effects of turning off the fan in a fan-forced evaporator. The energy consumption from a solenoid valve can be specified. ® Dual Evaporator Cycle - The control logic is similar to the Lorenz cycle, with the exception that an interchanger is not present between the evaporators, and that pure refrigerants are normally used with this cycle. An additional control option provided is alternately circuiting the refrigerant to one evaporator and then toanother. This would be accomplished by a switching valve. The energy consumption from such a valve can be specified. Energy Consumption ModelThe relationship between the hourly total cabinet heat loads (the refrigeration requirement at the evaporators), and the instantaneous capacity of the refrigeration cycle establishes the compressor run time (duty cycle = fraction of the hour that the compressor operates to meet the load): Duty = Cabinet-Load/(Evaporator-Capacity - Fan_Power) Cabinet-Load = Duty*Fan_On_Cabinet_Load + (1.0 - Duty)*Fan_Off Cabinet Load where, Duty = Calculated duty cycle (0 to 1) Fan_On_Cabinet_Load = Cabinet load during compressor operation Fan_Off Cabinet_Load = Cabinet load during compressor off-cycle The underlying assumption is that the thermal transients in the cabinet and in the refrigeration cycle are small. That is, it is assumed that the cabinet temperature iseither relatively constant over the complete cycle, or that the sensible heat corresponding to temperature swings between the compressor on-cycle and off-cycle conditions is small. The equations above link the time averaged cabinet loads to the instantaneous capacity of the refrigeration system. e Dual Loop Cycle

- Each refrigeration loop, which contains its own evaporator, compressor, andcondenser, acts independently to achieve the average temperatures specified for the individual compartments. The model simulates each loop separately.

e Lorenz Cycle

- The air temperatures approaching the two evaporators are assumed to be at the specified control points. Normally the evaporator loads will be unbalanced, requiring additional refrigeration to be delivered to one ofthe compartments during an off-cycle period for the other compartment. The control options are: 1) adjust the fresh food section temperature; 2) adjust the freezer temperature; 3) adjust the evaporator areas; 4) use a means to bypass the refrigerant cooling of one evaporators during a portion ofthe cycle to enable the other evaporator to meet its cabinet load; 5) allow an imbalance to occur. Control option 4 is intended to represent the use ofa solenoid valve for refrigerant bypass, or the effects of turning offthe fan in a fan-forced evaporator. The energy consumption from a solenoid valve can be specified. " Dual Evaporator Cycle

- The control logic is similar to the Lorenz cycle, with the exception that an interchanger is not present between the evaporators, and that pure refrigerants are normally used with this cycle. An additional control option provided is alternately circuiting the refrigerant to one evaporator and then to another. This would 

### be accomplished by a switching valve. The energy consumption from such a valve can 

### be specified. Energy Consumption Model The relationship between the hourly total cabinet heat loads (the refrigeration requirement at the evaporators), and the instantaneous capacity ofthe refrigeration cycle establishes the compressorrun time (duty cycle 

## =fraction ofthe hour that the compressor operates to meet the load):

where, Duty 

### =CabinecLoad!(Evaporator_Capacity

- Fan_Power) CabineCLoad

## =Duty*Fan_On_CabineCLoad + (1.0

- Duty)*Fan_OfCCabinet_Load

Duty 

## =Calculated duty cycle (0 to 1) Fan_On_CabinecLoad

## = Cabinet load during compressor operation Fan_Off_CabinecLoad

## = Cabinet load during compressor off-cycle The underlying assumption is that the thermal transients in the cabinet and in the refrigeration cycle are small. That is, it is assumed that the cabinet temperature is eitherrelatively constant overthe complete cycle, or that the sensible heat corresponding to temperature swings between the compressor on-cycle and off-cycle conditions is small. The equations above link the time averagedcabinetloads to the 

### instantaneous capacity ofthe refrigeration system.

3-6Once the duty cycle is determined, the energy consumption terms are easily calculated: Compressor energy use = Compressor power times the duty cycle Fan energy use = Fan power times the duty cycle Electronics (variable speed motor) = Electronics losses times the duty cycle Heaters and controls = Specified hourly total values frost energy = Net electrical input corresponding toheat of fusion of the moisture condensing on the cold evaporator. (Note that it is assumed that moisture will not freeze on a fresh food evaporator in the dual loop cycle, the Lorenz cycle, or the dual evaporator cycle.) Total Electrical Energy Use = Sum of above components CYCLE.DAT is the input data file to ERACYC. Output files are ERA .OUT and CYCLE.OUT. Full documentation of a single run would consist of the following files: ERA.OUT -- summary of energy use and cabinet loads CAEINET.DAT -- input to CAB CABINET.OUT -- output from CAB CYCLE.DAT -- input to ERACYC CYCLE.OUT -- results of cycle analysis Sample data input and output files are given in Section.7. 

### Once the duty cycle is detenuined, the energy consumption tenus are easily calculated: Compressor energy use 

## = Compressor power times the duty cycle Fan energy use = 

### Fan power times the duty cycle Electronics (variable speed motor) 

## = Electronics losses times the duty cycle Heaters and controls 

## = Specified hourly total values Defrost energy = 

### Net electrical input corresponding to heat offusion ofthe moisture condensing on the cold evaporator. (Note that it is assumed that moisture will not freeze on a fresh food evaporator in the dual loop cycle, the Lorenz cycle, orthe dual evaporator cycle.) Total Electrical Energy Use

## = Sum ofabove components CYCLE.OAT is the input data file to ERACYC. Output files are ERA.OUT and CYCLE.OUT. Full documentation ofa single run would consist ofthe following files: ERA.OUT

-- summary ofenergy use and cabinet loads CABINET.OAT

-- input to CAB CABINET.OUT

-- output from CAB CYCLE.OAT

-- input to ERACYC CYCLE.OUT

-- results ofcycle analysis Sample data input and output files are given in Section 7.

3-74.0 PUT P ROCESSOR



### 4.1 Menu Structure ERA uses an iterative, menu driven input processor. Menus, or instructions, are used at all levels of the input processing. For the most part, the appropriate response is a cursor movement, or a data entry, followed by use of the <Enter> key or <Pg Dn> key. The menu sc e has been developed to be as intuitive as feasible. Standard key stroke interpretations apply throughout the program: • <Esc> escape back to previous process or terminate current process • <Pg Up go back to previous menu • <Pg Dn> : go to next menu • <Enter> enter value or select option • <Home> move cursor to start of list • <End> move cursor to end of list In addition, a common menu structure has been designed for most of the functions of the input data processor. The program begins at the Main Menu, illustrated in Figure 4-1. Eleven specificactions are grouped into 4 sets. The first set deals with data file editing and manipulation (read data, edit cabinet data, edit cycle data, save data, delete data). A second set provides two means to return to DOS (temporary exit to DOS, quit program). A third set relates to the type of analysis to be performed (calculate cabinet loads, calculate energy). The last set provides a permanent, off-line copy of the input data (print data menus, write data menus to a file). An action is selected by moving the cursor to the desired option and pressing the <Enter> key. As illustrated in Figure 4-1, available help keys are shown at the top of each menu. Function key Fl always leads to a Help menu which explains the intent of the menu; function key F9 always provides an explanation of the use of special keys. As also illustrated in Figure 4

- 1, the bottom line of each menu normally lists important keys. For example, at the Main Menu level, touching the <Esc> key will move the cursor to the "Quit Program" option; pressing the <Pg Dn> key, or the <Enter> key will select the highlighted option. The Main Menu contains a two line description for the highlighted function. A new message will appear each time the cursor is moved. 4.0 INPUT PROCESSOR 4.1 Menu Structure 

### ERA uses an iterative, menu driven input processor. Menus, orinstructions, are used at all levels ofthe input processing. For the mostpart, the appropriate response is a cursor movement, or a data entry, followed by use ofthe <Enter> key or <Pg Dn> key. The menu structure has been developed to be as intuitive as feasible. Standardkey stroke interpretations apply throughout the program:



## .. <Esc>



## .. <PgUp>



## .. <PgDn> 

### " <Enter> 

### " <Home>



## .. <End> escape back to previous process orterminate current process go back to previous menu go to next menu enter value or select option

move cursor to start oflist

move cursor to endoflist In addition, a common menu structure has been designed for most ofthe functions of the input data processor. The program begins at the Main Menu, illustrated 

### in Figure 4-1. Eleven specific actions are grouped into 4 sets. The first set deals with data file editing and manipulation (read data, editcabinet data, editcycle data, save data, delete data). A second set provides two means to return to DOS (temporary exit to DOS, quitprogram). A third set relates to the type ofanalysis to be performed (calculate cabinetloads, calculate energy). The last setprovides a permanent, off-line copy ofthe input data (print data menus, write data menus to a file). An action is selected by moving the cursor to the desired option and pressing the <Enter> key. As illustrated 

### in Figure 4-1, available help keys are shown at the top ofeach menu. Function key Fl always leads to a Help menu which explains the intent ofthe menu; function key F9 always provides an explanation ofthe use of special keys. As also illustrated in

### Figure 4-1, the bottom line ofeach menu normally lists important keys. Forexample, at the Main Menu level, touching the <Esc> key will move the cursor to the "QuitProgram" option; pressing the <Pg Dn> key, orthe <Enter> key will select the highlighted option. The Main Menu contains a two line description for the highlighted function. A new message will appeareach time the cursor is moved.

4-1

### F1 = Help E RA F9 = Keys - Help Keys

Main Menu

Read in a to File Edit Cabinet Data Edit Cycle Data Save Data to File Delete Data File
Temporary Exit to DOS Quit Program

2 lane help menu goes here 

### e of Menu

Functions



### Descriptions o options

<Esc> = Q uit <Pg Dn> ® Select Key Strokes 

### Calculate Cabinet Loads Calculate Energy

Print Menus 

### Write Data Menus to a File



### Figure 4® 1: Main Menu ..,.. I N 

### F1 

# = Help IERA I F9

# = Keys 

# I Main Menu I I



### Read in a Data File Calculate Cabinet loads Edit Cabinet Data Calculate Energy Edit Cycle Data Save Data to File Delete Data File
Temporary Exit to DOS Print Menus Quit Program Write Data Menus to a File

2 line help menu goes here

<Esc> 

### =Quit <Pg Dn> 

# = Select 

### Figure 4-1: Main Menu Help Keys

Name of Menu

Functions

Descriptions of options
Key Strokes4.2 Retrieving and Saving Input Data Files

The first step in preparing an analysis is to create the input required for the analysis programs (CAB and ERACYC). This is accomplished by selecting a data file and then using the menu-driven editor. All data files have the extension ERA. When a request is made to retrieve data, ERA performs a search for all files (up to 200 in a sub-directory) with this extension and lists them in alphabetical order in the File Selection Menu, illustrated by Figure 4-2. To select an existing file move the cursor to highlight the name and press the <Enter> key. An automatic return to the next menu will then occur. If more than 40 data files are available for selection, pressing the <Pg Dn> key will scroll the screen forward to display the next 40 (or fewer) files. The <Pg Up> key will scroll backwards to the previous display of files. The File Selection Menu shows the name of the current data sub-directory (called the "Current Path"). To change to a different sub-directory, press the <Fl0> key and enter the data path (e.g., "\E \C ST"). If the data path is valid, a list of the available *.ERA data files will be displayed. Once a file is selected, it is read into the data "buffer" where it is available for editing or for analysis. The file name will appear in a window on the File Selection Menu (see Figure 4-2). If a new file is read in, this new name will be shown the next time the File Selection Menu is called. Two methods of creating a data file with a new name are provided. One method involves selecting a file, as described above, editing the data values, and then saving it under a new name. The process of saving the data creates a file with the desired name, but does not change the name of the file in the buffer. A second, more direct method, involves pressing the <F5> key first (see Figure 4-2) and then entering the (new) name of the file to be created as requested. The new name will automatically be entered into the buffer when the data is saved. The data in the new file will be same as those in the highlighted file. Hence, using the cursor, the highlight should be moved to the file most similar to the new file to be created. Once the data is edited it will be assigned the new file name. The procedure for saving a file is similar to the process of selecting a file. If a file name is the same as that shown in the buffer area (see Figure 4-2), the changed file can be saved simply by pressing the <F5> key. Otherwise, the name of the file must be typed where requested. The extension ERA is always assumed. Up to 8 characters may be entered. 4.3 Data File Management In some instances the user may wish to create and store more than 200 data files. ERA allows the definition of any valid DOS path for designating the location of the data files. This can be accomplished using the "path=" command in the SETUP.DAT file as discussed in Section 2 where a sample data file sub-directory \ERA\DATA was defined.



### 4-3 4.2 Retrieving and Saving Input Data Flies 

### The fIrst step in preparing an analysis is to create the input required for the analysis programs (CAB and ERACYC). This is accomplished by selecting a data fIle and then using the menu-driven editor. All data fIles have the extension .ERA. When a request is made to retrieve data, ERA performs a search for all fIles (up to 200 in a sub-directory) with this extension and lists them in alphabetical order in the File Selection Menu, illustrated by Figure 4-2. To select an existing fIle move the cursor to highlight the name and press the <Enter> key. An automatic return to the next menu will then occur. Ifmore than 40 data fIles are available for selection, pressing the <Pg Dn> key will scroll the screen forward to 

### display the next 40 (or fewer) fIles. The <Pg Up> key will scron backwards to the previous display offiles. The File Selection Menu shows the name ofthe current data sub-directory (called the "Current Path"). To change to a different sub-directory, press the <FlO> key and enter the data path (e.g., H\ERA\CHEST"). Ifthe data path is valid, a list ofthe available 

## *

.ERA data files will be displayed. Once a file is selected, it 

### is read into the data "buffer" where it 

### is available for editing orfor analysis. The file name will appear in a window on the File Selection Menu (see Figure 4-2). If

### a new file is read in, this new name will be shown the next time the File Selection Menu is called. Two methods ofcreating a data file with a new name are provided. One method involves selecting a file, as described above, editing the data values, and then saving it under a new name. The process of saving the data creates a file with the desired name, but does not change the name ofthe file in the buffer. A second, more direct method, involves pressing the <F5> key fIrst (see Figure 4-2) and then entering the (new) name ofthe file to be created as requested. The new name will automatically be entered into the buffer when the data is saved. The data in the new file will be same as those in the highlighted file. Hence, using the cursor, the highlight shouldbe moved to the file most similar to the new file to be created. Once the data is edited it will be assigned the new file name. The procedure for saving a file is similar to the process of selecting a file. Ifa file name is the same as that shown in the buffer area (see Figure 4-2), the changed file can be saved simply by pressing the <F5> key. Otherwise, the name ofthe file must be typed 

### where requested. The extension .ERA is always assumed. Up to 8 characters may be entered. 4.3 Data File Management 

### In some instances the user may wish to create and store more than 200 data fIles. ERA allows the defInition ofany valid DOS path for designating the location ofthe data fIles. This can be accomplished using the "path=" command in the SETUP.DAT file as discussed in Section 2 where a sample data file sub-directory\ERA \DATA was defIned.

4-3F1 = Help I ERA I F9 = Keys Help Keys 

### Buffer File: MODEL-D File Selection Menu Name of Menu

MODEL-A MODEL-B MODEL-C MODEL-D

Press <F5> to Create a New File

<Esc> = Main Menu <Pg Dn> ® roll Available files 

### Up to 40 per screen

Special Instruction



### K

## ey Strokes


### Figure 4-2: File Selection Menu Example F1 

# = Help IERA 

## I F9

# = Keys Help Keys Buffer File: MODEl_D 

# I File SelectilOn Menu I I 

### Name lOf Menu

MODEl_A MODEl_B MODEl_C Available fiies MODEl_D Up to 40 per screen



# IPress <F5> 

### tc Create a New File : Special InstructilOn

<Esc>

# = Main Menu <Pg Dn>

# = ScrlOll Key StrlOkes 

### Figure 4-2: File Selection Menu ExampleThe "path=" command might also be used to define sub-directories that are specific to

the type of refrigerating unit. For example, top-mount units might be stored in subdirectory \ERA\TOP, chest freezers in sub-directory \E \C ST, and so on. The limit of 200 data files will apply to each sub-directory defined. An external editor must be used to change the path command in SE P.DAT. An alternate means of creating additional file space in a sub-directory is to request the "Delete Data File" command from the Main Menu (see Figure 4-1). This function changes the file extension to EAK rather than actually erasing it. Hence if the file has been accidentally "deleted" it can be retrieved. The function allows additional file name space, but does not result in a reduction in the hard disk memory usage. 4.4 Editing Once a file has been read into the buffer, editing proceeds by selecting the type of data (cabinet loads or cycle data). As an example, Figure 4-3 illustrates the Cycle Data Edit Menu. The data set to be edited is selected by moving the cursor to highlight the item (e.g., Evaporator Design) and pressing the <Enter> or <Pg Dn> key. Figure 4-4 illustrates an example of a data edit menu for freezer insulation resistivities. Each data set is comprised of 1 to 14 values, which are displayed in the menu. They are edited by moving the cursor key to highlight the parameter, and then typing the new value, followed by pressing the <Enter> key. A moving "data entry box", with an arrow pointing to the current value, identifies the parameter to be changed. As the new data is entered it appears in this box until it is entered (by pressing the <Enter> key, or any other key that will move the cursor). Thesimplest way to enter a new value is to type the data into the box and then press a cursor key to move the box to a new location. 4.5 Getting Help As shown in Figure 4-4, an explanation of the data menu and the parameters to be edited can be obtained by pressing the <Fl> key. Figure 4-5 illustrates the structure of the Help menu. Each Help menu shows the name of the data menu, and provides textand simple line drawings, as needed, to explain the data requirements. If the information requires more than 17 lines, the text may be scrolled within the window by using the cursor or the <Pg Up> and <Pg Dn> keys. A bar indicator to either side of the text window symbolizes what portion of the Help menu appears on the screen. As noted in the top line of the Help menu (Figure 4-5), a return to the edit menu is made using the <Esc> key. A print out of the Help menu may be obtained by simultaneously pressing the <Alt>and <P> keys. The print port called is that defined in the SETUP.DAT file (see Section 2). If the program does not provide a print out or it hangs up at this point, the information in SETUP.DAT is probably incorrect for the particular computer hardware configuration. Options relating to printing from within ERA are explained in Section 2 and in the README.DOC file supplied with the program. The "path=" command might also be used to define sub-directories that are specific to the type ofrefrigerating unit. Forexample, top-mount units might be stored in subdirectory\ERA \TOP, chest freezers in sub-directory\ERA \CHEST, and so on. The limit of200 data files will apply to each sub-directory defined. An external editor must be used to change the path commandin SETUP.DAT. An alternate means ofcreating additional file space in a sub-directory is to request the "DeleteDataFile" command from the Main Menu (see Figure4-1). This function changes the file extension to .BAKrather than actually erasing it. Hence ifthe fIle has been accidentally "deleted" it can be retrieved. The function allows additional file name space, but does not result in a reduction in the harddisk memory usage. 4.4 Editing Data Once a file has been read into the buffer, editing proceeds by selecting the type ofdata (cabinet loads orcycle data). As an example, Figure 4-3 illustrates the Cycle Data Edit Menu. The data set to be editedis selected by moving the cursorto highlight the item (e.g., Evaporator Design) and pressing the <Enter> or <Pg On>key. Figure 4-4 illustrates an example ofa dataedit menu for freezer insulation resistivities. Each data set is comprised of 1 to 14 values, which are displayed in the menu. They are editedby moving the cursorkey to highlight the parameter, and then typing the new value, followed by pressing the <Enter> key. A moving "data entry box", with an arrow pointing to the current value, identifies the parameterto be changed. As the new data is entered it appears in this box until it is entered (by pressing the <Enter> key, or any otherkey that will move the cursor). The simplest way to enter a new value is to type the data into the box and then press a cursor key to move the box to a new location. 4.5 Getting Help As shown in Figure 4-4, an explanation ofthe data menu and the parameters to be edited can be obtained by pressing the <PI> key. Figure 4-5 illustrates the structure of the Help menu. EachHelp menu shows the name ofthe data menu, and provides text and simple line drawings, as needed, to explain the data requirements. Ifthe information requires more than 17 lines, the text may be scrolled within the window by using the cursor or the <PgUp> and <Pg On> keys. A barindicator to either side ofthe text window symbolizes what portion ofthe Help menu appears on the screen. As noted in the top line ofthe Help menu (Figure 4-5), a return to the edit menu is made using the <Esc>key. A print out ofthe Help menu may be obtained by simultaneously pressing the <Alt> and <P> keys. The printport calledis that defined in the SETUP.DAT file (see Section 2). Ifthe program does not provide a print outorit hangs up at this point, the information in SETUP.DAT is probably incorrect for the particular computerhardware configuration. Options relating to printing from within ERA are explainedin Section 2 and in the README.DOC file supplied with the program.

4-5

### , ; Sys

F1 ® Help E RA F9 ® Keys
Cycle Data Edit Menu

Cycle Type Condenser Design Refrigerants Compressor Design Evaporator sin Interchan ger(s)

2 line help menu goes here

<Esc> = Main M enu < Pg n> = Select f Menu

tins

Descriptions options
Key Strokes



### Figure -3: Cycle Data it Menu F1 

# = Help IERA I F9

# = Keys 

# I Cycle Data Edit Menu I I



### Cycle Type Condenser Design Refrigerants Compressor Design Evaporator Design Interchanger(s)

2 line help menu goes here

<Esc>

# = Main Menu <Pg Dn>

# = Select 

### Figure 4-3: Cycle Data Edit Menu Help Keys

Name of Menu

Options



### Descriptions of options
Key Strokes

### F1 = Hell! I E RA I F9 = Keys Help Keys
Freezer Insulation Resistivities

Resistivity ( 2- -cm

### )
* Top Wall 0.544 * Side Wall 0.544

* Back all 0.544

* Door 0.544 

### Wedge 0.544

Data Error Message * Press <F5> to Calculate Data



### <Esc> = Main Menu <Pg Dn> = Next Menu Name of data group

Data `} o nU location (Enter n value)


### Cursor

Special instruction

Key Strokes


### Figure 4-4: Data Edit Menu Example F1 

# = Help IERA I F9 

# = Keys 

# I Freezer Insulation Resistivities :
iResistivity (m2-clw-cm)

• Top Wall 

### 0.544 """'- 

### • Side Wall 

### 0.544 

# ----------

# --- '" Back Wall 

### 0.544 '" Door 

### 0.544

Wedge 

### 0.544

Data Error Message 

# /
'" Press 

### <FS> to Calculate Data <Esc>

# = Main Menu <Pg On> 

# = Next Menu 

### Figure 4-4: Data Edit Menu Example 

# ------ Help Keys

Name of data group

Data editing location (Enter new value)
Cursor

Special instruction

Key Strokes

### <Esc>: Return I Hel p Menu

er Insulation Resistivitles



### Text of Help nu

ERA < It®P>: Print 

### K

## ey strokes

Name of help menu

Up cursor to scroll up

Indicator

Down cursor to scroll down



### Figure ®5® Help Menu ample**~<S!E!:.:s~C~>~: ....!R~e:=.!t~u!!rn!.-**  _____

### -1I-!!H!!el!.Elp!...!M~e~n~u~L 1

_____

### ~<A~it-:!P~>:.:.:**..!P:.!:r~in~t..r----** Key strokes



### x xx 

# I Freezer Insulation Resistivities 11--

___ 

### -+
___ Name of help menu

### ~~----------------------------------_--~I~



### Text of 

### Help Menu



# I ERA 

# T

figure 4-5: Help Menu Example 

# - 

# t 1----+---- Up cursor to scroil up

# ~**~V'0\.J---+---lndicator** 

# »« 0-

1----+---- Down cursor to scroll downThe Keys Menu, accessed by pressing the <F9> key, defines the actions specific to

individual keys. A considerable amount of information has been collected in the Help and Keys menus. It is highly recommended that these menus be read at each level of the progr until the user is very familiar with ERA. 

### 4.6 Default I"'- ' Preparation of input data file involves editing, or selecting, current data. That is, the data preparation process always begins with the data file last read into the data buffer. By definition, therefore, the current data values in the selected file are default data. Suggestions for values, or ranges of values, for data parameters are found in the Help menus. 4.7 Calculation AssistsIn certain instances the requested data value may be difficult to assign without additional analysis. Examples include: the effective resistivity of a cabinet wall containing foam and vacuum insulation in a sandwich arrangement, evaporator UA value, and fan power in a variable-speed fan configuration. ERA provides a calculation assist to determine these values by calling secondary menus. Data values that can be estimated in this manner are indicated by an asterisk (*) next to the name of the parameter and a message at the bottom of the data window (see Figure 4-4). To call the calculation assist menu, position the highlight to the variable of interest using a cursor key and press the <F5> key. The structure of the calculation assist menu is shown in Figure 4-6 for the example of a variable speed fan. As with data edit menus, a Help menu is available by using the <Fl> key. A return to the calling menu is made by pressing the <Pg Dn> key or the <Esc> key. If the <Pg Dn> key is pressed, the calculation is performed and the results are automatically entered into the calling menu. To avoid making the calculation and to return directly to the calling menu, press the <Esc> key. In some instances, the data appearing in the calculation assist menu may appear not to be retained when the file is saved. This is because the assist facilities are considered to be only a means of calculating some data value that is saved in the menu from which the calculation assist function is called. This approach reduces the size of the data files, thereby speeding the file read and write functions and freeing up disk space.



### The Keys Menu, accessed by pressing the <P9> key, defmes the actions specific to individual keys. A considerable amountolin/ormation 

### has been collected in the Help andKeys menus. It is highly recommended that these menus be readateach level o/theprogram until the user is veryfamiliar with ERA. 4.6 Default Data 

### Preparation ofan input data me involves editing, or selecting, current data. That is, the data preparation process always begins with the data file last read into the data buffer. By definition, therefore, the current data values in the selected file are default data. Suggestions for values, orranges ofvalues, for data parameters are found in the Help menus. 4.7 Calculation Assists 

### In certain instances the requested data value may be 

### difficult to assign without additional analysis. Examples include: the effective resistivity ofa cabinet wall containing foam and vacuum insulation in a sandwich arrangement, evaporator 

### VA value, and fan powerin a variable-speed fan configuration. ERA provides a calculation assist to determine these values bycalling secondary menus. Data values that can be estimated in this manner are indicated by an asterisk (*) 

### next to the name ofthe parameter and a message at the bottom ofthe data window (see Figure 4-4). To call the calculation assist menu, position the highlight to the variable ofinterest using a cursor key andpress the <P5> key. The structure ofthe calculation assist menu is shown in Figure 4-6 for the example ofa variable speed fan. As with data edit menus, a Help menu is available by using the <PI>key. A return to the calling menu is made by pressing the <Pg Dn> key orthe <Esc> key. If

### the <Pg Dn>key is pressed, the calculation is performed and the results are automatically entered into the calling menu. To avoid making the calculation and to return directly to the calling menu, press the <Esc> key. In some instances, the data appearing in the calculation assist menumayappear not to be retained when thefile is saved. This is because the assist facilities are consideredto be onlya means of calculating some data value that is saved in the menu from which the calculation assist junction is called. This approach reduces the size of the data files, thereby speeding thefile readand writejunctions andfreeing up 

### disk space.

4-9

### F1 =He

Calculated Fan Power (w): 900 Calculated Air Flow ( ) : 15.5 Data editing location (Enter new value)


### Cursor

< c> ® Cancel < Pg n> ® Calculate Strokes ERA ®evs

Variable Speed Fan acne of variable

Rated Conditions

9.00 Air Flow Rate (US) 15.57 Power (w) Fan Speed (rpm) 3600.00

VSD Control Fan Speed (rpm) 3600.00



### Figure Calculation Assist u Example F1 

# = Help 

# I ERA 

# I F9

# = Keys 

# I Variable Speed Fan:

Rated Conditions
Fan Speed (rpm) 3600.00 -.:::.. 

### Power (w) 9.00 

# --------
---- Air Flow Rate (US) 15.57
VSD Control Fan Speed (rpm) 3600.00

Calculated Fan Power (w): 9.0 Calculated Air Flow (US): 15.5

<Esc>

# = Cancel <Pg Dn>

# = Calculate 

### Figure 4

..6: Calculation Assist Menu Example 

# r------ Help Keys

Name of variable

Data editing location (Enter new value)
Cursor

Key Strokes

### 4.8 input Data Error Trapping and Correction

All input data are checked against high and low limits whenever they are entered in a data edit menu. If the data value lies outside the expected range, an error message is written at the bottom of the data window (Figure 4-4). Depending on the nature of the parameters, one of three actions is taken: ® The data will not be accepted since it must lie within the limits. An example would be the code for the type of compressor (only 1 and 2 are allowed). ® The data must be above a minimum value but may exceed the upper limit. If the data is above the expected upper limit it may be accepted by pressing the <Esc> key (the menu will display this message). 

### ® Data below the expected range may be accepted by pressing the <Esc> key. In certain instances the user may wish to exceed the upper and lower limits , no matter what type of parameter is being edited

. This can be allowed by entering the statement "ignore

-limits = yes" in the SETUP .DAT file. The user should be cautioned that violation of expected limits may lead to erroneous answers or even a computer crash if an illogical request is made. Prior to executing the cabinet loads analysis, a check of the consistency of the data is made. Obvious errors, such as a door flange wider than the wall insulation, are caught and an error message is displayed

. The user m resolve the error before execution of the analysis is allowed. 4.9 Using DOS Within ERA In some instances the user may wish to call a DOS function or some other program (such as a data editor) without leaving ERA. An example situation might be the need to look at an ASCII file using an external editor to determine a data value to be entered into one of the ERA menus.This is accomplished by returning to the Main Menu and then choosing the "Temporary Exit to DOS" function (see Figure 4-1). A second version of COM MAND .COM will be executed, while leaving the ERA MENU program resident in memory. After all DOS requests have been completed a return to ERA will be made if the command "EXIT" is entered. The return will be made to the drive and directory containing the ERA program. Because ERA remains as a memory resident program during this temporary return to DOS, the available memory will be smaller (ERA requires about 390 K of memory). As a consequence, programs or DOS functions that require a large amount of memory may not work. In all instances the user should avoid loading another memory resident program during a temporary exit to DOS since this second memory resident program may prevent the release of the memory used by ERA upon exiting the program. In such a case the only recourse would be to reboot the computer.



### 4-11 4.8 Input Data Error Trapping and Correction All input data are checked against high and low limits whenever they are entered in a data edit menu. Ifthe data value lies outside the expected range, an errormessage is written at the bottom ofthe data window (Figure 4-4). Depending on the nature ofthe parameters, one ofthree actions is taken: " The data will not be accepted since it must lie within the limits. An example would be the code for the type ofcompressor (only 1 and 2 are allowed).

.. The data must be above a minimum value but may exceed the upper limit. Ifthe data is above the expected upper limit it may be accepted by pressing the <Esc> key (the menu will display this message). " Data below the expectedrange may be accepted by pressing the <Esc> key. In certain instances the user may wish to exceed the upper and lower limits, no matter what type ofparameteris being edited. This can be allowed by entering the statement "ignore_limits = yes" in the SETUP.DAT file. The user should be cautioned that violation ofexpected limits may lead to erroneous answers oreven a computer crash ifan illogical request is made. Priorto executing the cabinet loads analysis, a check ofthe consistency ofthe data is made. Obvious errors, such as a door flange wider than the wall insulation, are caught and an error message is displayed. The user**~** resolve the error before execution of the analysis is allowed. 4.9 Using DOS Within ERA In some instances the user may wish to call a DOS function or some otherprogram (such as a dataeditor) without leaving ERA. An example situation might be the need to look at an ASCII file using an external editor to determine a data value to be entered into one ofthe ERA menus. This is accomplished by returning to the Main Menu and then choosing the "Temporary Exit toDOS" function (see Figure 4-1). A second version ofCOMMAND.COM will be executed, while leaving the ERA MENU program resident in memory. After all DOS requests have been completed a return to ERA will be made ifthe command "EXIT" is entered. The return will be made to the drive and directory containing the ERAprogram. Because ERA remains as a memory residentprogram during this temporary return to DOS, the available memory will be smaller (ERA requires about 390 K ofmemory). As a consequence, programs orDOS functions that require a large amount ofmemory may not work. In all instances the user should avoid loading another memory resident program during a temporary exit to DOS since this second memory residentprogram may prevent the release ofthe memory used by ERA upon exiting the program. 

### In such a case the only recourse would be to reboot the computer.

4-114.10 Printing Input Data FilesA permanent copy of the data appearing in the data menus may be obtained by selecting the "Print Data Menus" or "Write Data Menus to a File" options from the Main Menu (see Figure 4-1). If the data are printed directly, the user must ensure that a printer is connected and that the correct print port is defined in the SE P.DAT file. Otherwise the printout may not occur or the computer may hang-up.A safer procedure is to write the data to a file and print it after leaving the ERA program. Data written to a file are stored with extension .INP. The name of the file, which contains the data as ASCII text, will be the same as the file in the buffer. 4.11 Program Execution As shown in Figure 3-1 (Section 3.2), a cabinet loads analysis and cycle analysis may be requested. This request occurs at the Main Menu where the user selects "Calculate Cabinet Loads" or "Calculate energy". The first request results in a calculation of the cabinet loads only. The second request results in both the loads and cycle analysis. The selected program will run to completion unless aborted by pressing the <Esc> key. Time requirements for the cabinet loads program are very small. The cycle model may require a small or large computational time, depending on the refrigeration cycle defined and the refrigerant characteristics. The most time consuming calculations will occur for a ternary refrigerant mixture in a two-evaporator cycle (such as the Lorenz or dual evaporator cycles which use a single compressor) where some adjustments to the cabinet set points or to the evaporator areas may be required to balance the loads and the evaporator capacities. As discussed earlier, ERACYC uses an iterative solution technique to solve the many coupled, non-linear equation. A screen display of the estimated temperatures and the refrigerant mass flow is made throughout the iteration process. Although not indicated on the screen, a solution may be "forced" by hitting the <F10> key. This will result in an assumed satisfaction of the solution tolerances following a condenser analysis and lead to termination of the analysis. A note will appear in the output that the solution was forced.

### As long as execution is not terminated by pressing the <Esc> key, a display of the output files will automatically occur. However, a direct return to DOS, without display of any files, will occur if the <Esc> key is pressed. 4.10 Printing Input Data Flies 

### A permanent copy ofthe data appearing in the data menus may be obtained by selecting the "Print Data Menus" or "Write Data Menus to a File" options from the Main Menu (see Figure 4-1). If

### the data are printed directly, the user must ensure that a printer is connected and that the correct print port is defined in the SETUP.DAT file. Otherwise the printout may not occuror the computer may hang-up. A safer procedure is to write the data to 

### a file and print 

### it after leaving the ERA program. Data written to a file are stored with extension .INP. The name ofthe file, which contains the data as ASCII text, will be 

### the same as the file in the buffer. 4.11 Program Execution 

### As shown in Figure 3-1 (Section 3.2), a cabinet loads analysis and cycle analysis may be requested. This request occurs at the Main Menu where the user selects "Calculate Cabinet Loads" or "Calculate energy". The first request results in a calculation ofthe cabinet loads only. The second request results in both the loads and cycle analysis. The selected program will run to completion unless aborted by pressing the <Esc> key. Time requirements for the cabinet loads program are very small. The cycle model may require a small orlarge computational time, depending on the refrigeration cycle defined and the refrigerant characteristics. The most time consuming calculations will occur for a ternary refrigerant mixture in a two-evaporator cycle (such as the Lorenz or dual evaporatorcycles which use a single compressor) where some adjustments to the cabinet set points or to the evaporator areas may be required to balance the loads and the evaporator capacities. As discussed earlier, ERACYC uses an iterative solution technique to solve the many coupled, non-linear equation. A screen display ofthe estimated temperatures and the refrigerant mass flow is made throughout the iteration process. Although not indicated on the screen, a solution may be "forced" by hitting the <FlO> key. This will result in an assumed satisfaction ofthe solution tolerances following a condenser analysis and lead to termination ofthe analysis. A note will appear in 

### the output that the solution was forced. As long as execution is not terminated by pressing the <Esc> key, a display ofthe output files will automatically occur. However, a direct return to DOS, without display of any files, will occur ifthe <Esc> key is pressed.

4-125.0 CABINET LOADS I PUT° DATA REFERENCE

The material within the present and following chapters are meant to supplement information provided within the ERA menu program. During the first run of the program and when questions arises concerning some data requirement the Help menu should be used (press the <Fl> key). A printed copy of each Help menu may obtained by pressing the <Alt-P> key from within the Help menu. Over 60 pages of Help menus can be printed out and assembled in a separate note book if desired. 

### 5.1 Title of Analysis Five lines of information may be entered as a description of the design analysis. The entered title will appear on the summary output. A full screen editor is built into the menu program. The Help or Keys screen describes the editing keys. 

### 5.2 Cabinet Type and Dimension Five basic designs are described: 1) top-mount refrigerator/freezer, 2) bottom-mount refrigerator/freezer, 3) side-by-side refrigerator/freezer, 4) chest fteezer, and 5) upright freezer. Specific design variables (such as the presence or absence of automatic defrost) are requested later in the menu structure. For the purposes of the analysis select the configuration that most closely represents the design under study. Not all refrigeration cycles are consistent with each cabinet configuration. To enable the user to edit portions of the input data in an arbitrary order, a consistency check between the specified cabinet data and cycle data is made only prior to the program execution step. The Help menu illustrates the definition of height, width and depth. The following conventions are adopted: ® Cabinet height is measured from the bottom to top of the cabinet, not from the floor.Hence, space below the cabinet that may contain a fan-forced condenser and compressor is not included in this parameter. ® Depth includes the cabinet doors. This dimension measures the distance from the outside (front) surface of the doors to the back of the cabinet. Protrusions such as a handle on the front of the cabinet or a cover over a wire harness on the back of the unit are NOT included in this value. To facilitate an understanding of the data request, the width of the gasket and the door edge thickness are requested. ERA interprets the depth of the refrigerated box, not containing the door, as the total depth minus the sum of the door edge thickness and the gasket width. Later data requests for the door thickness refer to the center thickness, thereby allowing the specification of doors that are thicker in the middle than at the edges. The effects of door thickness on the internal volume are taken into account.



### 5-1 5.0 CABINET LOADS INPUT DATA REFERENCE 

### The material within the present and following chapters are meant to supplement information provided within the ERA menu program. During the first run ofthe program and when questions arises concerning some data requirement the Help menu should be used (press the <PI>key). A printed copy of each Help menu may be obtained by pressing the 

### <Alt-I» key from within the Help menu. Over 60 pages ofHelp menus can be printed out and assembled in a separate note book ifdesired. 5.1 Title of Analysis 

### Five lines ofinfonnation may be entered as a description ofthe design analysis. The entered title will appear on the summary output A full screen editoris built into the menu program. The Help orKeys screen describes the editing keys. 5.2 Cabinet Type and Dimension 

### Five basic designs are described: 1) 

### top-mount refrigerator/freezer, 2) bottom-mount refrigerator/freezer, 3) side-by-side refrigerator/freezer, 4) chest freezer, and 5) upright freezer. Specific design variables (such as the presence orabsence ofautomatic defrost) are requested later in the menu structure. For the purposes of the analysis select the configuration that most closely represents the design under study. Not all refrigeration cycles are consistent with each cabinet configuration. To enable the user to edit 

### portions ofthe input data in an arbitrary order, a consistency check between the specified cabinet data andcycle data is made only prior to the program execution step. The Help menu illustrates the definition ofheight, width and depth. The following conventions are adopted:

.. Cabinet height is measured from the bottom to top ofthe cabinet, not from the floor. Hence, space below the cabinet that may contain a fan-forced condenser and compressor is not included in this parameter.

e 

### Depth includes the cabinet doors. This dimension measures the distance from the outside (front) surface ofthe doors to the back ofthe cabinet. Protrusions such as a handle on the front ofthe cabinet ora cover over a wire harness on the back ofthe unit are NOT included in this value. Tofacilitate an understanding ofthe data request, the width ofthe gasket and the dooredge thickness are requested. ERA interprets the depth ofthe refrigerated box, not containing the door, as the total depth minus the sum ofthe dooredge thickness and the gasket width. Later data requests for the door thickness refer to the center thickness, thereby allowing the specification ofdoors that are thicker in the middle than at the edges. The effects ofdoor thickness on the internal volume are taken into account.
5-1Wedge dimensions are requested in a separate menu. The cabinet wedge is the section of the cabinet near the door. In all cabinet types, except the chest freezer, the thicknessof the insulation is reduced near the door to accommodate the door geometry. Dimensions are assumed to be the same within each cabinet section (i.e., the side and top wedges of the freezer compartment in a top-mount unit are taken to be the same) although they may be different in one compartment from another. It is assumed that a freezer compartment in a refrigerator/freezer will always have a wedge with a taper; a wedge is often present in the fresh food section, but may be set to zero (typical of Chinese designs). An upright freezer will also have a wedge. The chest freezer is assumed to not have a wedge. An illustration of the wedge geometry is given in the Help screen. The wedge depth is the length of the taper from the front towards the back. Wedge width is the thickness of the cabinet at the front. 5.3 Refrigerated Volumes ERA will calculate internal volumes of the cabinet compartments based on the input data for the cabinet dimensions. The calculated volume is used in the simulation of thecontribution to the cabinet loads from door openings. If the calculated volumes are significantly different from the manufacturer's specifications then the input data is probably faulty. For example, the location of the mullion at the wrong position within the cabinet will result in an incorrect calculation of the individual compartment volumes. See Help screen for additional information. Normally, the compressor will be located in a space at the rear, bottom of the cabinet, where it is cooled by air blown over the condenser or by natural convection. This space requirement will reduce the food storage volume of the cabinet located above, and will also affect the net external surface area available for heat exchange with the room. A separate menu is provided to describe the compressor compartment. Three cases are described: 1) the compressor is located outside the dimensions of the cabinet, requiring no reduction in food storage volume; 2) the bottom portion of the back wall is slanted; and 3) the bottom portion of the cabinet contains a compressor space with a horizontal wall. If the compressor is located outside the envelope of a rectangular cabinet box enter 0 for the three data values requested. Otherwise enter data values as directed by the Help menu. 

### 5.4 Freezer and Fresh Food CabinetsTwo menus request the data input for each cabinet section: 1) the wall and door thicknesses, and 2) insulation resistivity for each wall element and door. The net resistance of each cabinet element is determined by the resistivity and the thickness. Drawings of the cabinets showing the requested data are given in the Help screens.In most instances, interpretation of the wall thickness requests should be straight forward. If the thickness varies over the element, such as the floor of a fresh food cabinet that may have thicker insulation over the compressor, use an averaged thickness value.



### 5-2 Wedge dimensions are requested in a separate menu. The cabinet wedge is the section ofthe cabinet near the door. In all cabinet types, except the chest freezer, the thickness ofthe insulation is reduced near the door to accommodate the door geometry. Dimensions are assumed to be the same within each cabinet section (i.e., the side and top wedges ofthe freezer compartment in a top-mount unit are taken to be the same) although they may be different in one compartment from another. It

### is assumed that a freezer compartment in a refrigerator/freezer will always have a wedge with a taper; a wedge is often presentin the fresh food section, but may be setto zero (typical ofChinese designs). An upright freezer will also have a wedge. The chest freezer is assumed to not have a wedge. An illustration ofthe wedge geometry is given in the Help screen. The wedge depth is the length ofthe taperfrom the front towards the back. Wedge width is the thickness ofthe cabinet at the front. 5.3 Refrigerated Volumes 

### ERA will calculate internal volumes ofthe cabinet compartments based on the input data for the cabinet dimensions. The calculated volume is used in the simulation ofthe contribution to the cabinet loads from door openings. If

### the calculated volumes are significantly different from the manufacturer's specifications then the input data is probably faulty. Forexample, the location ofthe mullion at the wrong position within the cabinet will result in an incorrect calculation ofthe individual compartment volumes. See Help screen for additional information. Normally, the compressor will be located in a space at the rear, bottom ofthe cabinet, where 

### itis cooled by air

### blown over the condenser orby natural convection. This space requirement will reduce the food storage volume ofthe cabinet located above, and will also affect the net external surface area available for heatexchange with the room. A separate menu is provided to describe the compressor compartment. Three cases are described: 1) the compressor is locatedoutside the dimensions ofthe cabinet, requiring no reduction in food storage volume; 2) the bottom portion ofthe back wall is slanted; and 3) the bottom portion ofthe cabinet contains a compressor space with a horizontal wall. If

### the compressor is located outside the envelope ofa rectangular cabinetbox enter0 for the three data values requested Otherwise enter data values as directed by the Help menu. 5.4 Freezer and Fresh Food Cabinets 

### Twomenus request the data input for each cabinet section: 1) the wall and door thicknesses, and 2) insulation resistivity for each wall element anddoor. The netresistance ofeach cabinet elementis determined by the resistivity and the thickness. Drawings of the cabinets showing the requested data are given in the Help screens. In most instances, interpretation ofthe wall thickness requests shouldbe straight forward. If

### the thickness varies overthe element, such as the floor ofa fresh food cabinet that may have thickerinsulation over the compressor, use an averaged thickness value.



### 5-2The specified thickness of a wall containing a sandwich of foam and a vacuum insulation panel should be the total thickness (neglecting the thickness of the liner). The thermal resistivities are properties of the materials of construction and the construction methods

. For example, typical CFC

- 11 blown polyurethane foams have a resistivity of 0.55 m2-C

-cm. Some vacuum insulation panels may have resistivities of greater than 1.5. Default values for many of the insulation strategies under consideration are available to the user by using the <F5> function key. Some example insulation values are: HCFC Blown Foam 0.48 m2- C/W -cm 7 hr-ft2-F/Rtu-in CFC- Blown Foam 0.55 m2-C -cm 8 hr-ft2-F/Rtu-in Water Blown Foam 0.42 m2-C/W-cm 6 hr-ft2-F/Ptu-in Evacuated Powder 1.73 m2-C -cm 25 hr-ft2-F/Rtu-in Evacuated Aerogel 1.39 m2-C -cm 20 hr-ft2-F/Rtu-in The corresponding thermal conductivity of the HCFC blown foam is (typically): Metric units: 0.0206 W/m-C 

### Calory units: 0.0177 kCal/m-hr-C English units: 0.0119 Bth/hr-ft-F When a composite insulation system is used, an average resistivity for the wall should be specified. ERA provides a method of estimating the average resistivity of a composite consisting of a foam sandwich containing a vacuum insulation panel (see Appendix A). The general case assumes a vacuum insulation panel located between inner and outer foam panels and surrounded by foam along all four edges. This calculational assist is reached by pressing the <F5> key within the Insulation Resistivity menu. This will cause an additional menu to be displayed which requests information on the design of the insulation system. A Help menu is available which shows the geometry and describes each of the required input parameters . Typical material property values are also given in the Help menu. Once within the calculational assist menu, two additional editing assists are provided:1) the fraction of the refrigerator wall consisting of foam may be determined by pressing the <F4> key and entering the vacuum panel thickness ; and 2) the amount of foam along the four edges of the panel may be determined by pressing the <F5> key and entering the fractional coverage of the wall by the panel

. These functions are explained in f urther depth in the Help menu. The user should note that the data displayed in this calculational assist menu will be the last entered and will be carried forth to the next set ofcalculations . Hence, the user should always be sure that the entire set of data shown in the menu applies to the specific configuration being analyzed. After leaving the calculation assist menu (press <Pg Dn> key), the calculated net resistivity for the insulation system is directly entered into the Insulation Resistivity menu. Note that different constructions can be used at various locations of the cabinet.



### 5-3 The specified thickness ofa wall containing a sandwich offoam and a vacuum insulation panel should be the total thickness (neglecting the thickness ofthe liner). The thermal resistivities are properties ofthe materials ofconstruction and the construction methods. Forexample, typical CFC-ll blown polyurethane foams have a resistivity of0.55 m2-C/W-cm. Some vacuum insulation panels may have resistivities ofgreater than 1.5. Default values for many ofthe insulation strategies under consideration are available to the user by using the <F5> function key. Some example insulation values are: HCFC Blown Foam CFC-ll Blown Foam Water BlownFoam Evacuated Powder Evacuated Aerogel 0.48 m2

### -CIW-cm 0.55 m2-C/W-cm 0.42 m2-C/W -cm 1.73 m2-C/W-cm 1.39 m2-C/W-cm 7 hr-ff-FlBtu-in 8 hr-fr-FlBtu-in 6 hr-ff-FlBtu-in 25 hr-ff-FlBtu-in 20 hr-fr-FlBtu-in The corresponding thermal conductivity ofthe HCFC blown foam is (typically): Metric units: Calory units: English units: 0.0206 W /m-C 0.0177 kCaVm-hr-C 0.0119 Bth/hr-ft-F When a composite insulation system is used, an average resistivity for the wall should be specified. ERA provides a method ofestimating"the average resistivity ofa composite consisting ofa foam sandwich containing a vacuum insulation panel (see Appendix A). The general case assumes a vacuum insulation panel located between inner and outer foam panels and surrounded by foam along all four edges. This calculational assist is reached by pressing the <F5> key within the Insulation Resistivity menu. This will cause an additional menu to be displayed which requests information on the design ofthe insulation system. A Help menu is available which shows the geometry and describes each ofthe required inputparameters. Typical material property values are also given in the Help menu. Once within the calculational assist menu, two additional editing assists 

### are provided: I) the fraction ofthe refrigerator wall consisting offoam may be determined by pressing the <F4> key andentering the vacuum panel thickness; and 2) the amount offoam along the four edges ofthe panel may be determined by pressing the <F5> key and entering the fractional coverage ofthe wall by the panel. These functions are explained in further depth in the Help menu. The usershouldnote that the data displayed in this calculational assistmenu will be the last enteredandwill be carriedforth to the nextsetof calculations. Hence, the usershouldalways be sure that the entire setof data shown in the menuapplies to the specific configuration being analyzed. After leaving the calculation assist menu (press <Pg Dn> key), the calculated net resistivity for the insulation system is directly enteredinto the Insulation Resistivity menu. Note that different constructions can be used at various locations ofthe cabinet.

5-35.5 Mullion The mullion is the wall between the fresh food and freezer sections of the refrigerator.One is found in configuration type 1 (top-mount: horizontal mullion), type 2 (bottommount: horizontal mullion) and in type 3 (side-by-side: vertical mullion). By definition, there is no mullion in a chest freezer or upright freezer. Typically the resistivity of the mullion insulation is less than that of the foam walls since a removable insulation is often installed in this area. The resistivity is normally about half that of the walls. 

### 5.6 Air and Cabinet Temperatures The room air and cabinet temperatures establish the heat loads of each compartment on the refrigeration system. For a DOE closed door test simulation a room air temperature of 32.2 C (90 F) is ordinarily specified, along with a freezer temperature of -15 C (5 F)and a fresh food cabinet temperature of 3.3 C (38 F). Temperatures must also be specified for under the cabinet (where the compressor is normally located) and for "air entering the condenser". There will be some uncertainty in these temperatures, since a heat balance is not modeled for the space under the cabinet. Both the compressor and condenser release considerable heat to this compartment. As a rule of thumb, the airtemperature in this region should be 10 to 15 F (5 to 10 C) higher than the room temperature. ERA also contains algorithms for estimating the effects of open door loads on energy consumption

. For these analyses (which require door opening schedules) a typical room temperature will be 18 to 24 C (64 to 75 F). 

### 5.7 Door Opening Schedules The schedule of door openings is defined here to establish the net sensible and latent load heat inputs to the cabinet during the hour. The model assumes an initial complete spilling of the cold air and replacement with warm, relatively more humid, room air, followed by a longer term free convective driven air exchange. The controlling parameters are: the room relative humidity, the number of times each door is opened during the hour, and the average duration of each opening. Parameters controlling the sensible and latent loads are: room temperature, cabinet temperature, room relative humidity, number of openings/hour,' average duration of each door opening, and type of defrost (manual or automatic). A typical schedule for door openings might be: 

### Fresh Food Door - Opening/hr. 2.5 - Duration (sec) 20 Freezer Door - Opening/hr. 1 - Duration (sec) 15 5.5 Mullion 

### The mullion is the wall between the fresh food and freezer sections ofthe refrigerator. One is found in configuration type 1 (top-mount: horizontal mullion), 

### type 2 (bottommount: horizontal mullion) andin type 3 (side-by-side: vertical mullion). By definition, there is no mullion in a chest freezer orupright freezer. Typically the resistivity ofthe mullion insulation is less than that ofthe foam walls since a removable insulation is often installed in this area. The resistivity is normally about halfthat ofthe walls. 5.15 Air and cabinet Temperatures 

### The room 

### air andcabinettemperatures establish the heat loads ofeach compartment on the refrigeration system. For a DOE closed door test simulation a room 

### air temperature of32.2 C (90 F) is ordinarily specified, along with a freezer temperature of-15 C (5 F) 

### and a fresh food cabinet temperature of3.3 C (38 F). Temperatures must also be specified for under the cabinet (where the compressor is normally located) and for 

### "air entering the condenser". There will be some uncertainty in these temperatures, since a heat balance is not modeled for the space under the cabinet. Both the compressor and condenserrelease considerable heat to this compartment As a rule ofthumb, the 

### air temperature in this region should be 10 to 15 F (5 to 10 C) higher than the room temperature. ERA also contains algorithms for estimating the effects ofopen door loads on energy consumption. Forthese analyses (which require door opening schedules) a typical room temperature will be 18 to 24 C (64 to 75 F). 

### 5.7 Door Opening Schedules 

### The schedule ofdoor openings is definedhere to establish the net sensible andlatentload heatinputs to the cabinetduring the hour. Themodel assumes an initialcomplete spilling ofthe cold 

### airandreplacement with warm, relatively more humid, room 

### air, followed by a longer term free convective driven 

### air exchange. The controlling parameters are: the roomrelativehumidity, the numberoftimes eachdooris openedduring the hour, andthe average duration ofeach opening. Parameters controlling the sensible and latent loads are: room temperature, cabinet temperature, room relative humidity, number ofopenings/hour,'average duration of each dooropening, andtype ofdefrost (manual or automatic). A typical schedule for door openings might be: Fresh Food Door

- Opening/hr.

- Duration (sec) FreezerDoor

- Opening/hr.

- Duration (sec)

5-4 

### 2.5 20

1 

### 15Moisture exchange with the room will result in condensation in both cabinets and frost

build-up in the fi-eezer section. It is assumed that all moisture entering the fresh food section will end up as frost on the evaporator of a single evaporator system. Frost buildup is not assumed to occur in the fresh food cabinet of a two evaporator system. Defrost energy may result from use of a resistance heating element in the evaporator. This energy is added to the defrost energy specified for the closed door condition, and is reported as "Defrost" in the summary output. 

### 5.8 Gasket Heat Leaks The gasket areas around the cabinet doors are sources of heat due to conduction loads from the room air along the cabinet and door flanges, and through the gasket itself.Correct estimates of the heat leaks must take into consideration the geometry and materials used in the wall panels and doors. Reference values for the gasket heat leaks may be obtained from the Help menu by pressing the <Fl> function key. All gasket heat leaks are expressed in units of conductance per length of the gasket. The net leak is determined by the program from the total door perimeter and from the outside-inside air temperature difference. Because of the low values of the conductance, enter the data in units of W/m-1000. A typical value is 10 W/m-100 C temperature difference. 5.9 Defrost and Controls Energy Use Electrical energy consumption consists of compressor energy, fan energy, anti-sweat energy, and other (ancillary) sources. Such ancillary energy includes automatic defrost and controls. It is assumed that any electrical energy consumed within the cabinet is converted to an equivalent heat load that must be removed by the refrigeration system.The data menu defines constant and cycle-dependent electrical energy uses, not including fan energy or anti-sweat energy. Automatic defrost energy usage is a cycle-dependent load, which is normally triggeredby a controller that keeps track of compressor operation. Under closed-door test conditions, a typical defrost system might use a 450 watt heater, activated for 10 minutes once every 10 hours of compressor run-time. Additional defrost energy will be required under normal usage conditions. ERA assumes that the additional defrost loads resulting from door openings are additive to the defined closed-door automatic defrost energy. Energy use from timers and other sources may be defined as being cycle-dependent(related to the compressor run-time) or constant. The locations of these loads determine their effects on the cabinet heat loads. For example, a defrost timer located in the space below the fresh food section will not add to the cabinet heat load, whereas electric defrost heat will add to the load. 5.10 Electric Anti-Sweat HeatMoisture control on the outside of the cabinet may be accomplished by the use of electric heaters in the area of the cabinet flanges and the mullion. Ordinarily an "energysaver" switch is supplied with the refrigerator to allow these heaters to be disabled. Moisture exchange with the room will result in condensation in both cabinets and frost build-up in the freezer section. It is assumed that all moisture entering the fresh food section will end up as frost on the evaporator ofa single evaporator system. Frost buildup is not assumed to occurin the fresh food cabinet ofa two evaporator system. Defrost energy may result from use ofa resistance heating element in the evaporator. This energy is added to the defrost energy specified for the closed door condition, and is reported as "Defrost" in the summary output. 5.8 Gasket Heat leaks The gasket areas around the cabinet doors are sources ofheat due to conduction loads from the room air along the cabinet and door flanges, and through the gasket itself. Correct estimates ofthe heat leaks must take into consideration the geometry and materials used in the wall panels and doors. Reference values for the gasket heat leaks may be obtained from the Help menu bypressing the <PI> function key. All gasket heat leaks are expressed in units ofconductance per length ofthe gasket. The net leak is determined by the program from the total doorperimeter and from the outside-inside air temperature difference. Because ofthe low values ofthe conductance, enter the data in units ofW/m-lOOC. A typical value is 10 W/m-lOO C temperature difference. 5.9 Defrost and Controls Energy Use Electrical energy consumption consists ofcompressorenergy, fan energy, anti-sweat energy, and other (ancillary) sources. Such ancillary energy includes automatic defrost and controls. It is assumed that any electrical energy consumed within the cabinet is converted to an equivalent heat load that must be removed by the refrigeration system. The data menu defines constant and cycle-dependent electrical energy uses, not including fan energy or anti-sweat energy. Automatic defrost energy usage is a cycle-dependent load, which is normally triggered by a controller that keeps track ofcompressor operation. Underclosed-door test conditions, a typical defrost system might use a 450 watt heater, activated for 10 minutes once every 10 hours ofcompressorrun-time. Additional defrost energy will be required under normal usage conditions. ERA assumes that the additional defrost loads resulting from door openings are additive to the defined closed-door automatic defrost energy. Energy use from timers and other sources may be defined as being cycle-dependent (related to the compressorrun-time) orconstant. The locations ofthese loads determine their effects on the cabinet heat loads. For example, a defrost timer located in the space below the fresh food section will not add to the cabinet heat load, whereas electric defrost heat will add to the load. 5.1 0 Electric Anti-Sweat Heat Moisture control on the outside ofthe cabinet may be accomplished by the use ofelectric heaters in the area ofthe cabinet flanges and the mullion. Ordinarily an "energysaver" switch is supplied with the refrigerator to allow these heaters to be disabled.

5-5Under a 0 E closed-door test, the refrigerator is operated under both conditions -- with the heaters on and with the heaters off. ERA can be run for both cases, and the results then averaged to simulate the test conditions. A simple approximation that can be employed is to run ERA once using one half of the heater power to represent an average condition. Since the heaters are normally installed immediately under the cabinet flanges and/or the mullion, a portion of the heat will leak into the cabinet. A typical fractional heat leak is 20% - 40% in the cabinet flange region, and 40% - 80% in the mullion region.Electrical heat applied in the mullion region will contribute to heat loads in both compartments. Because of the lower freezer temperature, more of the heat will likely flow to this compartment. 5.11 Refrigerant Line Anti

-Sweat Heat Moisture control on the outside of the cabinet may be accomplished by the use of refrigerant lines in the area of the cabinet door flanges and the mullion. To simplifyconstruction, a combination of refrigerant lines around the cabinet flanges and electrical heaters in the mullion region might also be used. Either a refrigerant vapor line (containing superheated vapor leaving the compressor) or a refrigerant liquid line (containing refrigerant leaving the condenser) may be usedfor this function. An advantage resulting from using a liquid line is that additional subcooling occurs prior to entering the capillary tube. In actual practice, the refrigerant entering a liquid line around the door flange or across the mullion may be in two-phase, with condensation completed within the liquid line.This may be desirable to limit the total refrigerant charge. ERA cannot model this situation, since it assumes completion of condensation in the condenser. The condenser subcooling should be set to zero when a liquid line is represented. The refrigerant enthalpy decrease from the use of a vapor or liquid line is dependent on the compressor run time. File CYCLE.OUT (the cycle analysis output file) should be reviewed to ensure that the specified cycle-average refrigerant line heating has notresulted in an excessive enthalpy drop (e.g., liquid subcooling to below ambient conditions). A warning message indicating excessive heat withdrawal from the liquid line will appear in the summary output file (ERA.OUT) whenever the refrigerant is cooled below room temperature. In this instance, the degree of refrigerant line heat should be reduced and replaced with an equivalent amount of electric anti- sweat heat. Since the electric anti-sweat heat is switchable, only one-half of the heat deficit should be entered as electric anti-sweat heat to represent average conditions for the DOE closed door test.(For example, assume that a 6 watt switchable anti-sweat heater is to replaced by a liquid line. Under the closed door test condition, the average condition is represented by 3 watts electrical anti-sweat heat. Since the liquid line heat is not switchable, the 3 watts electrical heat should be replaced by 6 watts liquid line heat. If only 4 watts ofliquid line heat can be withdrawn without cooling the refrigerant below room temperature, enter 4 watts liquid line heat and supplement it with 1 watt average electrical antisweat heat.)


### 5-6 Under a DOE closed-door test, the refrigerator is operated under both conditions

-- with the heaters on and with the heaters off. ERA can be run for both cases, and the results then averaged to 

### simulate the test conditions. A simple approximation that can be employed is to run ERA once using one halfofthe heater powerto represent an average condition. Since the heaters are normally installed immediately under the cabinet flanges and/or the mullion, a portion ofthe heat will leak into the cabinet. A typical fractional heat leak is 20%

- 40% in the cabinet flange region, and 40%

- 80% in the mullion region. Electrical heat applied in the mullion region will contribute to heat loads in both compartments. Because ofthe lower freezer temperature, more ofthe heat will likely flow to this compartment. 5.11 Refrigerant line Anti-Sweat Heat 

### Moisture control on the outside ofthe cabinet may be accomplished by the use of refrigerant lines in the area ofthe cabinet door flanges and the mullion. To simplify construction, a combination ofrefrigerant lines around the cabinet flanges and electrical heaters in the mullion region might also be used. Either a refrigerant vapor line (containing superheated vapor leaving the compressor) or a refrigerant liquid line (containingrefrigerant leaving the condenser) may be used for this function. An advantage resulting from using a liquid line is that additional subcooling occurs prior to entering the capillary tube. In actual practice, the refrigerant entering a liquid line around the door flange oracross the mullion may be in two-phase, with condensation completed within the liquid line. This may be desirable to limit the total refrigerant charge. ERA cannot model this situation, since it 

### assumes completion ofcondensation in the condenser. The condenser subcooling should be set to zero when a liquid line is represented. The refrigerant enthalpy decrease from the use ofa vapororliquid line is dependent on the compressorrun time. File CYCLE.OUT (the cycle analysis output file) should be reviewed to ensure that the specifiedcycle-averagerefrigerant line heating has not resulted in an excessive enthalpy drop (e.g., liquid subcooling to below ambient conditions). A warning message indicating excessive heat withdrawal from the liquid line will appear in the summary output me (ERA.OUT) whenever the refrigerant is cooled below room temperature. In this instance, the degree ofrefrigerant line heat should be reduced andreplaced with an equivalent amount ofelectric anti-sweat heat. Since the electric anti-sweat heat is switchable, only one-halfofthe heat deficit should be entered as electric anti-sweat heat to represent average conditions for the DOE closed door test. (For example, assume that a 6 watt switchable anti-sweat heater is to replaced by a liquid line. Under the closed door test condition, the average condition is represented by 3 watts electrical anti-sweat heat. Since the liquid line heat is not switchable, the 3 watts electrical heat shouldbe replaced by 6 watts liquid line heat. If

### only 4 watts of liquid line heat can be withdrawn without cooling the refrigerant below room temperature, enter4 watts liquid line heat and supplement it with 1 watt average electrical antisweat heat.)


### 5-6For the dual loop cycle, ERA assumes that the refrigerant line used for anti-sweat

and/or mullion heating is associated with the freezer loop. 5.12 Penetratic ' 1 ut Heat inputs to the cabinet not associated with electrical sources can be specified as"penetration heat inputs." One such heat source would be associated with through-thedoor ice service. In this instance, estimate of the additional heat leak due to the presence of themechanism in the door can be made and included as a direct heat leak.This menu can used for all heat inputs that cannot be directly associated with electrical energy usage. 

### For the dual loop cycle, ERA assumes that the refrigerant line used for anti-sweat and/or mullion heating is associated with the freezer loop. 5.12 Penetration Heat Input 

### Heat inputs to the cabinet not associated with electrical sources can be 

### specified as "penetration heat inputs." One such heat source would be associated with through-thedoor ice service. In this instance, an estimate ofthe additional heat leak due to the presence ofthe mechanism in the door can 

### be made and included as a direct heat leak. This menu can be 

### used for all heat inputs that cannot be directly associated with electrical energy usage.



### 5-76.0 REFRIGERATION CYCLE INPUT DATA REFERENCE

6.1 Cycle TypeFour generic cycle types are described: 1) standard single evaporator and single compressor configuration; 2) Lorenz cycle; 3) dual loop cycle, and 4) dual evaporator cycle. The standard cycle (type 1) uses a baffle arrangement to mix the airs from the freezer and fresh food cabinets before entering the evaporator. Two evaporators are employedin the Lorenz cycle (type 2), with two interchangers used to promote additional subcooling of the refrigerant leaving the condenser. Two independent refrigeration loops are used in the dual loop cycle (type 3) to cool the fresh food and freezer sections; each loop has its own components. The dual evaporator cycle (type 4) is similar to the Lorenz cycle, except that pure refrigerants are normally used. The evaporators are in series, with little interchangebetween the lines connecting the two evaporators and the liquid line leaving the condenser. Pure refrigerants or refrigerant mixtures can be used with any of the cycles. Normally a binary or ternary non-azeotropic mixture (NARM) is used with the Lorenz cycle, and a pure refrigerant or a near-azeotropic mixture will be used with the standard single evaporator cycle and with the dual loop cycle.Not all of the cycle types apply to each of the cabinet designs. The table below illustrates the allowable cycles for the five cabinet designs:
Top Mount Bottom Side-by- Chest Upright

Mount Side Freezer Freezer 1: Single Evap 2: Lorenz 3: Dual Loop 4: Dual Evap * * * * * * * * * * * A check of the consistency between the cabinet design and refrigeration cycle is made prior to execution of an energy analysis.Control of the evaporator loads in the Lorenz cycle or the dual evaporator cycle is difficult if fans are not used. Without some active control method, the cabinet temperatures will change until the loads and evaporator capacities are in balance. ERA provides six analysis options for the Lorenz and dual evaporator cycles: 0) no control (allow an imbalance in the loads); 1) "mathematically" adjust the relative sizes of the evaporators in the two compartments to obtain balanced loads; 2) adjust the fresh food cabinet temperature to balance the loads; 3) adjust the freezer cabinet temperature to balance the loads; 4) use a flow control valve to alternately direct the refrigerant toone evaporator at a time; and 5) activate a solenoid valve to isolate one of the evaporators during part of the cycle, while allowing refrigerant to flow to the other evaporator whenever the compressor operates.



### 6-1 6.0 REFRIGERATION CYCLE INPUT DATA REFERENCE 6.1 Cycle Type Fourgeneric cycle types are described: 1) standard single evaporator and single compressor configuration; 2) Lorenz cycle; 3) dual loop cycle, and 4) dual evaporator cycle. The standard cycle (type 1) uses a baffle arrangement to mix the 

### airs from the freezer and fresh food cabinets before entering the evaporator. Two evaporators are employed in the Lorenz cycle (type 2), with two interchangers used to promote additional subcooling ofthe refrigerant leaving the condenser. Two independentrefrigeration loops are used in the dual loop cycle (type 3) to cool the fresh food and freezer sections; each loop has its own components. The dual evaporator cycle (type 4) is similar to the Lorenz cycle, except that pure refrigerants are normally used. The evaporators are in series, with little interchange between the lines connecting the two evaporators and the liquid line leaving the condenser. Pure refrigerants orrefrigerant mixtures can be used with any ofthe cycles. Normally a binary or ternary non-azeotropic mixture (NARM) is used with the Lorenz cycle, and a pure refrigerant or a near-azeotropic mixture will be used with the standard single evaporator cycle and with the dual loop cycle. Not all ofthe cycle types apply to each ofthe cabinet designs. The table below illustrates the allowable cycles for the five cabinet designs:
Top Mount Bottom Side-by- Chest Upright Mount Side Freezer Freezer
1 : Single Evap * * * * * 2: Lorenz * * * 3: Dual Loop * * * 4: Dual Evap * * * A check ofthe consistency between the cabinet design and refrigeration cycle is made prior to execution ofan energy analysis. Control ofthe evaporator loads in the Lorenz cycle or the dual evaporator cycle is difficult iffans are not used. Without some active control method, the cabinet temperatures will change until the loads and evaporator capacities are in balance. ERA provides six analysis options for the Lorenz and dual evaporator cycles: 0) no control (allow an imbalance in the loads); 1) "mathematically" adjust the relative sizes ofthe evaporators in the two compartments to obtain balanced loads; 2) adjust the fresh food cabinet temperature to balance the loads; 3) adjust the freezer cabinettemperature to balance the loads; 4) use a flow control valve to alternately direct the refrigerant to one evaporator at a time; and 5) activate a solenoid valve to isolate one ofthe evaporators during part ofthe cycle, while allowing refrigerant to flow to the other evaporator whenever the compressor operates.

6-1Option 0 allows an imbalance to occur; it provides the user maximum control over theanalysis. Option 1 assumes that the total heat exchanger area is held constant; it is provided as a "design analysis" tool, to determine the necessary distribution of evaporator areas to achieve balanced loads. Options 2 and 3 result in a change in'the cabinet temperatures until the loads in each cabinet are met by the individual evaporators. Option 4 assumes that the flow control valve will sequentially divert the refrigerant to one and then to the other of the two evaporators over a portion of the cycle. At any given time in the cycle, only one evaporator receives refrigerant. Option 5 assumes that the refrigerant flows through both evaporators during the majorportion of the cycle, and then diverts it past one of the evaporators during the remainder of the cycle. This can be accomplished by a solenoid valve (requiring some energy use). In concept, the use of active fan control accomplishes the same objective; deactivation of an evaporator fan during a portion of the cycle effectively removes the fan-forced heat exchanger from the circuit by substantially reducing its heat transfer capacity. 6.2 RefrigerantsThirty-four refrigerants, whose data values are stored in a built-in data base, can be utilized as either pure refrigerants or as components of a mixture:

01 = R11 , 02 = R12, 03 = R13, 04 = R13B1, 05 = R K 06 = R22, 07 = R23, 08 = R1 13, 09 = R114, 10 = R1 42b, 11 = R152a, 12 = R216a, 13 = R125, 14 = R1 43a, 15 = R134a, 16 = R123, 17=RC318, 18=8134, 19=RC270, 20=R141b 21 = S02, 22 = R290, 23 = R600, 24 = R600a, 25 = R32, 26 = R1270, 27 = R124, 28 = 8115, 29 = CE216, 30 = El 25, 31 = R21, 32 = R143, 33=R218, 34=E134.

The refrigerant data menu references two function keys: ® <P4>: pressing this key results in display of the refrigerant properties and chemical formulas. This may be valuable when selecting one refrigerant in favor of another or when putting together candidate refrigerant mixtures. ® <F5>: pressing this key results in selection of default interaction parameters for mixture pairs. Option 0 allows an imbalance to occur; it provides the user maximum control over the analysis. Option 1 assumes that the total heat exchanger area is held constant; it is provided as a "design analysis" tool, to determine the necessary distribution ofevaporator areas to achieve balanced loads. Options 2 and 3 result in a change in 'the cabinet temperatures until the loads in each cabinet are met by the individual evaporators. Option 4 assumes that the flow control valve will sequentially divert the refrigerant to one and then to the other ofthe two evaporators over a portion ofthe cycle. At any given time in the cycle, only one evaporatorreceives refrigerant. Option 5 assumes that the refrigerant flows through both evaporators during the major portion ofthe cycle, and then diverts it past one ofthe evaporators during the remainder ofthe cycle. This can be accomplished by a solenoid valve (requiring some energy use). In concept, the use ofactive fan control accomplishes the same objective; deactivation ofan evaporator fan during a portion ofthe cycle effectively removes the fan-forced heat exchanger from the circuitby substantially reducing its heat transfer capacity. 6.2 Refrigerants Thirty-fourrefrigerants, whose data values are stored in a built-in database, can be utilized as eitherpure refrigerants or as components ofa mixture:
01=R11, 05 = R14, 09=R114, 13=R125, 17 = RC318, 21 = S02, 25 = R32, 29= CE216, 33 = R218, 02 = R12, 06= R22, 10 = R142b, 14 = R143a, 18 = R134, 22 = R290, 26 = R1270, 30 = E125, 34= E134. 03 = R13, 07= R23, 11 = R152a, 15 = R134a, 19= RC270, 23= R600, 27= R124, 31 

### =R21,

The refrigerant data menu references two function keys: 04 = R13B1, 08= R113, 12 = R216a, 16 = R123, 20 = R141b 24 = R600a, 28=R115, 32 = R143,

• <F4>: pressing this key results in display ofthe refrigerant properties and chemical formulas. This may be valuable when selecting one refrigerant in favor ofanother orwhen putting together candidate refrigerant mixtures.

• <F5>: pressing this key results in selection ofdefault interaction parameters for mixture pairs.

6-2

### 6.3 Evaporator Design

The options for evaporator design are: ® type: fan forced or natural convection ® air flow pattern: cross-flow or counter-flow ® location of natural convection evaporator: in cabinet space, cold-plate (mounted onthe cabinet wall with one side facing the cabinet space), or directly behind the plastic liner. The state of the refrigerant leaving the evaporator is determined by specification of. 1) the superheat (C) at the exit of the evaporator, 2) the superheat (C) at the exit of the interchanger between the evaporator and the compressor, or 3) the refrigerant quality (less than 1.0) at the exit of the evaporator.Specification of the evaporator exit condition (quality or superheat) avoids the necessity to model the flow control device (cap-tube). The superheat condition at the evaporator exit actually corresponds to a design goal. Normally, the selection of cap-tube diameter and length will depend on the amount of superheat desired. The heat transfer from a fan-forced evaporator will depend on the overall U-values in the two-phase (evaporating) and single-phase (superheating) regimes. These values, along with the refrigerant pressure drop, may be estimated by pressing the <F5> key where noted in the evaporator menu and by inputting the requested heat exchanger design information. For computational purposes, the heat exchanger is assumed to be composed of circular tubes containing refrigerant in cross-flow with air. The face area is determined from the number and spacing of the tubes in the transverse direction (perpendicular to the air flow) and the tube length. The depth of the heat exchanger is determined from the number and spacing of the tubes in the direction of the air flow. A "deep" heat exchanger (more than 3 - 5 tubes deep) will behave like a counter-flow design. The user may also elect to enter an overall UA value for the evaporator. This may be useful if a measured value is available. In this instance, ERA will assume a constant U-value along the length of the heat exchanger.If fan-forced, the evaporator may be considered as being in cross-flow or in counterflow. For a pure refrigerant, in the absence of a significant pressure drop, there is essentially no difference between the two. However, with a refrigerant mixture that results in a large temperature glide from the entrance to the exit of the evaporator, a counter-flow design may be more efficient.Solution of counter-flow heat transfer in the evaporator is more difficult and time consuming than cross-flow. Because of this, the following recommendations are made: ® select the cross-flow model unless a large temperature glide is expected. Set the number of two-phase nodes equal to 1 in file CYCLE.TOL; 

### 6.3 Evaporator Design The options for evaporator design are: " type: fan forced or natural convection



### .. air flow pattern: cross-flow orcounter-flow

o 

### location ofnatural convection evaporator: in cabinet space, cold-plate (mounted on the cabinet wall with one side facing the cabinet space), ordirectly behind the plastic liner. The state ofthe refrigerant leaving the evaporator is determined by specification of: 1) the superheat (C) at the exit ofthe evaporator, 2) the superheat (C) at the exit ofthe interchanger between the evaporator and the compressor, or 3) the refrigerant quality (less than 1.0) at the exit ofthe evaporator. Specification ofthe evaporator exit condition (quality or superheat) avoids the necessity to model the flow control device (cap-tube). The superheat condition at the evaporatorexit actually corresponds to a design goal. Normally, the selection ofcap-tube diameter and length will depend on the amount of superheat desired. The heat transfer from a fan-forced evaporator will depend on the overall V-values in the two-phase (evaporating) and single-phase (superheating) regimes. These values, along with the refrigerant pressure drop, may be estimated by pressing the <F5> key where noted in the evaporator menu and by inputting the requested heat exchanger design information. For computational purposes, the heat exchanger is assumed to be composed ofcircular tubes containing refrigerant in cross-flow with 

### air. The face area is determined from the number and spacing ofthe tubes in the transverse direction (perpendicular to the 

### air flow) and the tube length. The depth ofthe heat exchanger is determined from the number and spacing ofthe tubes in the direction ofthe 

### air flow. A "deep" heat exchanger (more than 3 - 5 tubes deep) will behave like a counter-flow design. The user may also elect to enter an overall 

### VA value for the evaporator. This may be useful ifa measured value is available. In this instance, ERA will assume a constant V-value along the length ofthe heat exchanger. Iffan-forced, the evaporator may be considered as being in cross-flow orin counterflow. For a pure refrigerant, in the absence ofa significant pressure drop, there is essentially no difference between the two. However, with a refrigerant mixture that results in a large temperature glide from the entrance to the exit ofthe evaporator, a counter-flow design may be more efficient. Solution ofcounter-flow heat transfer in the evaporator is more difficult and time consuming than cross-flow. Because ofthis, the following recommendations are made: " select the cross-flow model unless a large temperature glide is expected. Set the number oftwo-phase nodes equal to 1in file CYCLE.TOL;

6-3® explore the effects of counter-flow heat transfer if the temperature glide is larger than 10 C

. Set the number of nodes in the two

-phase regime equal to 3 in file CYCLE.TOL. ERA uses a built

-in natural convection model to establish the rate of natural convection heat exchange between the evaporator plate and the cabinet air. Both radiative and free convective heat transfer contribute to the net cooling accomplished by the evaporator.A data menu requests information relating to the geometry of the evaporator to calculate the refrigerant pressure drop

. Evaporation and sensible heat exchange will determine the two-phase and vapor velocities, which will in turn establish the refrigerant pressure loss across the evaporator. Three generic types of natural convection evaporators are modeled: 1) a flat plate located within the cabinet space, 2) a cold

-plate configuration, and 3) a behind-theliner configuration. If the evaporator is mounted behind the plastic liner, an additional heat transfer resistance will be encountered, with a typical reduction in the cooling capacity of 10 to 15 %. ERA assumes an added resistance equal to 2

.5 mm polystyrene (0.9 cal/hr-cm-C thermal conductivity). A higher cooling capacity will be achieved from a plate of a given size that is locatedwithin the cooled space since both sides of the plate will be available for heat convection and since the wall temperature will not be significantly affected by the plate. A cold-plate evaporator or a behind-the-liner (mounted directly under the liner) type of evaporator provides more internal volume , but will result in an increased refrigeration load due to the cooling of the wall by the evaporator and a reduced foam thickness. An ERA data menu requests information on the evaporator heat transfer area

. This is the total effective area available for heat transfer. For a free convective evaporator located within the cabinet space, the total area of both sides of the evaporator should be entered; for a cold-plate evaporator, only the area of the plate facing the cabinet space should be entered. ERA was not intended to substitute for a detailed heat exchanger design program. For instance, if a roll-bond type free convective evaporator design is employed, some estimate of the effects of thermal bond resistance on the effective heat transfer area must be made by the user. Normally, the level of uncertainty in the net effective area will not have a large impact on the cycle performance calculations. For the refrigerator

/freezer configurations , a portion of a natural convection freezer evaporator may be located in the mullion area between the two cabinet sections. Theevaporator thickness determines the volume occupied in the cabinet wall and/or mullion that would otherwise be occupied by insulation. Specification of this geometry, which satisfies the definition of a cold-plate evaporator, will be requested only for a natural convection design. A fan-forced freezer evaporator of a refrigerator

/freezer is always assumed to be located in the back of the freezer section (vertical orientation). 

### " explore the effects ofcounter-flow heat transfer ifthe temperature glide is larger than 10 C. Set the number ofnodes in the two-phase regime equal to 3 in me CYCLE.TOL. ERA uses a built-in natural convection model to establish the rate ofnatural convection heat exchange between the evaporator plate and the cabinet 

### air. Both radiative and free convective heat transfer contribute to the net cooling accomplished by the evaporator. A datamenu requests information relating to the geometry ofthe evaporator to 

### calculate the refrigerant pressure drop. Evaporation and sensible heat exchange will determine the two-phase and vapor velocities, which will in turn establish the refrigerant pressure loss across the evaporator. Three generic types ofnatural convection evaporators are modeled: 1) a flat plate located within the cabinet space, 2) a cold-plate configuration, and 3) a behind-thelinerconfiguration. If

### the evaporator is mounted behind the plastic liner, an additional heat transfer resistance will be encountered, with a typical reduction in the cooling capacity of 10 to 15%. ERA assumes an added resistance equal to 2.5 mm polystyrene (0.9 cal/hr-cm-C thermal conductivity). A higher cooling capacity will be achieved from a plate ofa given size that is located within the cooled space since both sides ofthe plate will be available for heat convection and since the wall temperature will not be significantly affected by the plate. A cold-plate evaporatoror a behind-the-liner (mounted directly under the liner) type of evaporator provides more internal volume, but will result in an increasedrefrigeration load due to the cooling ofthe wall by the evaporator and a reduced foam thickness. An ERA data menu requests information on the evaporator heat transfer area. This is the total effective area available for heat transfer. For a free convective evaporator located within the cabinet space, the total area ofboth sides ofthe evaporator should be entered; for a cold-plate evaporator, only the area ofthe plate facing the cabinet space should be entered. ERA was not intended to substitute for a detailed heat exchanger design program. For instance, ifa roll-bond type free convective evaporator design is employed, some estimate ofthe effects ofthermal bondresistance on the effective heat transfer area must be made by the user. Normally, the level of uncertainty in the net effective area will not have a large impact on the cycle performance calculations. Forthe refrigerator/freezer configurations, a portion ofa natural convection freezer evaporator may be located in the mullion area between the two cabinet sections. The evaporator thickness determines the volume occupied in the cabinet wall and/or mullion that would otherwise be occupied by insulation. Specification ofthis geometry, which satisfies the definition ofa cold-plate evaporator, will be requested only for a natural convection design. A fan-forced freezer evaporator ofa refrigerator/freezer is always assumed to be located in the back ofthe freezer section (vertical orientation).

6-46.4 Condenser Design

As with the evaporator, the condenser may employ a fan-forced or natural convectiondesign; if fan-forced it may be cross-flow or counter flow. Liquid subcooling is specified as a design goal (this replaces need for a mass inventory balance about the refrigerator loop to calculate the subs ling). Hot-wall condensers (tubes attached to the underside of the outer skin of the cabinet) may be specified for any of the refrigerator/freezer or freezer designs other than the side-by-side unit. Free convection (static) condensers may be used for all designs. Fan-forced condensers are assumed to be located under the cabinet. The increase in air temperature under the cabinet from condenser (and compressor shell) heat losses must be estimated andspecified by the program user. It is assumed that most of a static or fan-forced heat exchanger has flat or wire fins to increase the effective heat transfer area. The condenser fins provide extended heat transfer area to increase the overall effectiveness of the heat exchanger. Wire fins will act to break up the air flow (promote turbulence) as well as to provide additional heat transfer area. The issues relating to cross-flow versus counter-flow heat transfer are essentially the same as discussed above for the evaporator.Heat losses will occur along the line from the compressor discharge port to the condenser inlet. These may be uncontrolled, as in a bare or partially insulated line, or may result from cabinet flange heating. A hot gas loop used for cabinet flange heating willnormally lose a fraction of its heat to both of the cabinet sections as well as to the environment. 

### 6.5 Calculation Assist Menus for Evaporator and Condenser UA Values If the analysis involves alternate refrigerants or various compressor designs, use of the calculation assist menus to calculate the heat exchanger UAs is recommended. TheUA analysis algorithms take into consideration the influence of refrigerant thermopyhisical properties and the refrigerant mass flow rate on the refrigerant-side heat transfer (see Appendix B). It is noted that the calculation of UA values is done within the data input program, rather than during the cycle simulation. The required inputs for the refrigerant mass flow rate and evaporator inlet quality may not be known until the cycle analysis has been completed. Once the cycle analysis has been run, the output file (CYCLE.OUT) should be reviewed to ensure that the calculated mass flow rate and inlet quality agree with those used to determine the heat exchanger UAs. If the values differ significantly, the analysis should be rerun using updated values for these parameters in the heat exchanger calculation assist menus. 

### 6.6 Compressor Design Separate models are provided for a reciprocating compressor and a rotary compressor. The models differ in the treatment of suction gas heating within the shell and in the volumetric efficiency algorithm (see Appendix B).


### 6-5 6.4 Condenser Design As with the evaporator, the condenser may employ a fan-forced or natural convection design; iffan-forced 

### it may be cross-flow orcounter flow. Liquid subcooling is specified as a design goal (this replaces the need for a mass inventory balance about the refrigerator loop to calculate the subcooling). Hot-wall condensers (tubes attached to the underside ofthe outer skin ofthe cabinet) may be specified for any ofthe refrigerator/freezer or freezer designs other than the side-by-side unit. Free convection (static) condensers may be used for all designs. Fan-forced condensers 

### are assumed to be located under the cabinet. The increase in air temperature under the cabinet from condenser (and compressor shell) heat losses must be estimated and specified by the program user. It is assumed that most ofa static orfan-forced heat exchanger has flat or wire fins to increase the effective heat transfer area. The condenser fins provide extended heat transfer area to increase the overall effectiveness ofthe heat exchanger. Wire fins will act to break up the air flow (promote turbulence) as well as to provide additional heat transfer area. The issues relating to cross-flow versus counter-flow heat transfer 

### are essentially the same as discussed above for the evaporator. Heat losses will occur along the line from the compressor discharge port to the condenser inlet. These may be uncontrolled, as in a bare orpartially insulated line, or may result from cabinet flange heating. A hot gas loop used for cabinet flange heating will normally lose a fraction ofits heat to both ofthe cabinet sections as well as to the environment. 6.5 Calculation Assist Menus for Evaporator and Condenser UA Values Ifthe analysis involves alternate refrigerants orvarious compressordesigns, use ofthe calculation assist menus to calculate the heat exchangerUAs is recommended. The U A analysis algorithms take into consideration the influence ofrefrigerant thermopyhisical properties and the refrigerant mass flow rate on the refrigerant-side heat transfer (see Appendix B). Itis noted that the calculation ofU A values is done within the data input program, rather than during the cycle simulation. The required inputs for the refrigerant mass flow rate and evaporator inlet quality may not be known until the cycle analysis has been completed. Once the cycle analysis has been run, the output file (CYCLE.OUT) should be reviewed to ensure that the calculated mass flow rate and inlet quality agree with those used to determine the heat exchanger UAs. Ifthe values differ significantly, the analysis should be rerun using updated values for these parameters in the heat exchanger calculation assist menus. 6.6 Compressor Design Separate models 

### are providedfor a reciprocating compressor and a rotary compressor. The models differ in the treatment ofsuction gas heating within the shell and in the volumetric efficiency algorithm (see Appendix B). 

### 6-5A compressor map based model, an EER and capacity model, or an efficiency model may be selected to describe compressor performance. The compressor map approach utilizes a table of performance data (supplied by the user) for the specific refrigerant. A sample performance map table (a file, which may have any valid 8 character name with the extension TAE) is shown below:

Sample Compressor Map Data Table (*.TAB) Name of Compressor 12.3 Mass flow at standard rating point (lb/hr or k ) 3 Number ofdata points along evaporating temperature axis 3 Number ofdata points along condensing temperature axis 1 Compressor type (1 - reciprocating; 2 - rotary) 1 Units for capacity , temperature data, and mass flow

(1 - btu/hr, deg F, lb/hr; 2 - kcal/hr, deg C, kg/hr)
Capacity Data
Cond Temp Evaporating Temperature

-30 -10 10 110 441 837 1428 120 419 794 1384 

### 130 397 762 1340

Cond Temp Compressor Power, Watts

Evaporating Temperature 

### -30 -10 10 110 107 160 210 120 108 160 214 130 108 162 218

The EER and capacity model requests a single calorimeter data point at the standard test condition with CFC-12 refrigerant. Correlations for the suction gas superheat and shell heat loss (discussed in APPENDIX B) are use to determine values for the clearance volume and the compression efficiency. A correction for the thermodynamic characteristics of the circulating refrigerant is made. A compressor map based model, an EER and capacity model, or an efficiency model may be selected to describe compressor performance. The compressor map approach utilizes a table ofperformance data (supplied by the user) for the specific refrigerant. A sample performance map table (a me, which may have any valid 8 character name with the extension .TAB) is shown below: Sample Compressor Map Data Table (*.TAB) Name ofCompressor 12.3 Mass flow at standardrating point (lb/hr orkg/hr) 3 Number ofdatapoints along evaporating temperature axis 3 Number ofdata points along condensing temperature axis 1 Compressor type (1

- reciprocating; 2 - rotary) 1 Units for capacity, temperature data, and mass flow (1

- btu/hr, deg F, Ib/hr; 2 - kcal/hr, deg C, kg/hr) Capacity Data

Cond Temp Evaporating Temperature -30 -10 10 110 441 837 1428 120 419 794 1384 130 397 762 1340
Compressor Power, Watts Cond Temp Evaporating Temperature -30 -10 10 110 107 160 210 120 108 160 214 130 108 162 218

The EER and capacity modelrequests a single calorimeterdatapoint at the standard test condition with CFC-12 refrigerant. Correlations for the suction gas superheat and shell heat loss (discussed in APPENDIX B) are use to determine values for the clearance volume and the compression efficiency. A correction for the thermodynamic characteristics ofthe circulating refrigerant is made.

6-6To extend the performance data to other conditions and other refrigerants , it is necessary to know the conditions under which the data were obtained. These parameters are the displacement and the method of compressor can cooling during the calorimeter test. The efficiency model requests information concerning the compressor components and the piston displacement

. Approximate values for the shell losses and internal tubing losses must be supplied as well. Specific instructions for defining these data are pro-vided in the Help menu for the physically based model. The efficiency model may only be used for a reciprocating compressor. However, the analysis approach allows the evaluation of v ariable speed drive options, an investigation of the effects of motor efficiency on perfo rmance, and the direct specification of size as measured by the displacement. The cycle model (ERACYC) calculates the mass flow of the refrigerant pumped by the compressor, based on the estimated conditions at the suction port of the pump and the volumetric efficiency

. Suction gas superheat at the suction port is determined from the heat exchange internal to the compressor can. The can loss parameter , which defines the rate of shell cooling, directly affects the internal heating.Additional details about the input data requirements for the compressor models are provided by the Help menu (press <Fl> key). Appendix B summarizes the algorithms employed for the various models. 

### 6.7 Cycling Losses Cycling losses are caused by thermal transient effects in the evaporator and condenser as well as by migration of refrigerant from the condenser to the evaporator during the off-cycle. Some system designs with a rotary compressor employ a shut-off valve between the condenser and evaporator to reduce the off-cycle refrigerant flow. In those designs, it is may be advantageous to maintain tight temperature control in the cabinets to force more frequent cycling, thereby maintaining a higher average temperature evaporatorand a lower average temperature condenser. For the standard design, without a shutoff valve, it will be advantageous to minimize the compressor stop/starts, thereby minimizing the losses associated with refrigerant migration (a typical cycle time might be 20 minutes on and 30 minutes off). ERA provides two options relative to cycling losses: 1) ignore losses on compressor energy use; or 2) adjust the calculated steady-state compressor power for losses usingan algorithm based on the cycling rate. At a cycling rate of 2 cycles per hour, the estimated cycling loss would be 2.2%. The cycling model is described in Appendix E.There are indications that a shut-off valve can actually increase the cycle-average compressor performance above the steady-state level [6]. At a cycling rate of 2 cpm, the "cycle loss model" predicts an efficiency gain of about 3%. Hence the overall efficiency increase from using a shut-off valve (with a rotary compressor) may be about 5%. This is discussed in further detail in Appendix B. To extend the performance data to other conditions and otherrefrigerants, 

### it is necessary to know the conditions under which the data were obtained. These parameters are the displacement and the method ofcompressor can cooling during the calorimeter test. The efficiency model requests information concerning the compressor components and the piston displacement. Approximate values for the shell losses and internal tubing losses must be supplied as well. Specific instructions for defining these data are provided in the Help menu for the physically based model. The efficiency model may only be used for a reciprocating compressor. However, the analysis approach allows the evaluation ofvariable speed drive options, an investigation ofthe effects ofmotor efficiency on performance, and the direct specification of size as measured by the displacement The cycle model (ERACYC) calculates the mass flow ofthe refrigerant pumped by the compressor, based on the estimated conditions at the suction port ofthe pump and the volumetric efficiency. Suction gas superheat at the suction port is determined from the heat exchange internal to the compressor can. The can loss parameter, which defines the rate of shell cooling, directly affects the internal heating. Additional details about the input data requirements for the compressor models are provided by the Help menu (press <P1> key). Appendix B summarizes the algorithms employed for the various models. 6.7 Cycling Losses Cycling losses are caused by thermal transient effects in the evaporator and condenser as well as by migration ofrefrigerant from the condenser to the evaporatorduring the off-cycle. Some system designs with a rotary compressor employ a shut-offvalve between the condenser and evaporator to reduce the off-cycle refrigerant flow. In those designs, it is may be advantageous to maintain tight temperature control in the cabinets to force more frequent cycling, thereby maintaining a higher average temperature evaporator and a lower average temperature condenser. For the standard design, without a shutoffvalve, it will be advantageous to minimize the compressor stop/starts, thereby minimizing the losses associated with refrigerant migration (a typical cycle time might be 20 minutes on and 30minutes off). ERA provides two options relative to cycling losses: 1) ignore losses on compressor energy use; or2) adjust the calculated steady-state compressorpower for losses using an algorithm based on the cycling rate. At a cyclingrate of2 cycles per hour, the estimated cycling loss would be 2.2%. The cycling model is described in Appendix B. There are indications that a shut-offvalve can actually increase the cycle-average compressor performance above the steady-state level [6]. At a cycling rate of2 cpm, the "cycle loss model" predicts an efficiency gain ofabout 3%. Hence the overall efficiency increase from using a shut-offvalve (with a rotary compressor) may be about 5%. This is discussed in further detail in Appendix B.

6-76.8 Interchangers The line leaving the condenser is normally in thermal contact with the line leaving the evaporator on its way to the compressor. This line contact provides liquid subcooling at the expense of additional superheat in the suction line. ERA requests information relating to the effectiveness of the interchanger (and of the interchanger between the fresh food and freezer evaporators in the Lorenz cycle). Additional heat transfer may also take place in the refrigeration line between the interchanger and compressor shell inlet (normally heating of the refrigerant by the room air). 

### 6.8 Interchangers The line leaving the condenser is normally in thermal contact with the line leaving the evaporator on its way to 

### the compressor. This line contactprovides liquid subcooling at the expense ofadditional superheat in the suction line. ERArequests information relating to the effectiveness ofthe interchanger (and ofthe interchanger between the fresh food and freezer evaporators in the Lorenz cycle). Additional heat transfer may also take place in the refrigeration line between the interchanger and compressor shell inlet (normally heating ofthe refrigerant by the room air).

6-87.0 SAMPLE PROBLEM



### 7.1 Multiple Pathway "Model D" Prototype Design Use of the ERA model for loads and energy use analysis is illustrated for the Multiple Pathway Model D refrigerator [5]. This design is intended to be a composite of design features for a prototype 18 cu-ft top-mount refrigerator/freezer that would meet the 1993 energy standard by a comfortable margin using off-the-shelf technology. Thespecific design approach adopted provides an outer shell 76 cm (30 inches) wide, amenable to thicker wall insulation without exceeding normal width constraints. Figures 7-1 through 7-3 illustrate design features (where the dimensions are in units of inchesto facilitate comparison with typical designs of current model refrigerators). The overall characteristics of the prototype model are summarized in Table 7-1, where data are shown in both English and metric units. Most of the parameters in Table 7-1 are well defined (e.g., dimensions, temperatures, compressor characteristics). Others are either estimates (e.g., temperature under fresh food cabinet) or "typical" (e.g., gasket heat loss). The model user can easily adopt alternate assumptions and investigate the effects of uncertainties in these parameters on the predicted cabinet loads and energy use. 7.2 Input Data Menus (MODEL _ .I P) The data file for the sample problem is MODEL_D.ERA. Figure 7-4 shows the input data menus for the sample problem. Individual data menusand values are shown for each data block defining the sample problem, exactly as displayed during the input data processing phase of the analysis. The specific menus are consistent with the type of cabinet (top-mount, refrigerator/freezer) and the type of refrigerator cycle (single evaporator, fan-forced). Only data relevant to the particular problem are shown. This data is not normally output for each analysis. However, the user may choose to create and save the menu data as part of the documentation for an analysis. The output (MODEL_D.INP) is obtained from the Main Menu of ERA using the "Print Data Menus" or "Write Data Menus to a File" function. 7.3 Intermediate Cabinet Loads Data File (C INET.DAT) The first executable module of ERA (MENU.EXE) creates an intermediate data filewhich serves as the input to the cabinet loads program (see Figure 3-1 for the relationship between the executable program modules and the data transfers). As illustrated in Figure 7-5, the structure of the intermediate file is designed to facilitate interpretation by the program user. Because of the overall structure of ERA, the intermediate data file is not meant to bemodified. Program module CAB.EXE will read the file, whose structure will be different for each cabinet type, and perform the cabinet loads analysis. The user may choose to print out this file for documentation purposes. 7.0 SAMPLE PROBLEM 7.1 Multiple Pathway "Model D" Prototype Design 

### Use ofthe ERA model for loads and energy use analysis is illustrated for the Multiple Pathway Model D refrigerator [5]. This design is intended to be a composite ofdesign features for a prototype 18 cu-ft top-mount refrigerator/freezer that would meet the 1993 energy standard by a comfortable margin using off-the-shelftechnology. The specific design approach adopted provides an outer shell 76 cm (30 inches) wide, amenable to thicker wall insulation without exceeding normal width constraints. Figures 7-1 through 7-3 illustrate design features (where the dimensions are in units ofinches to facilitate comparison with typical designs ofcurrent model refrigerators). The overall characteristics ofthe prototype model are summarized in Table 7-1, where data are shown in both English and metric units. Most ofthe parameters in Table 7-1 are well defined (e.g., dimensions, temperatures, compressor characteristics). Others are either estimates (e.g., temperature under fresh food cabinet) or "typical" (e.g., gasket heat loss). The model user can easily adopt alternate assumptions and investigate the effects ofuncertainties in these parameters on the predicted cabinet loads and energy use. 7.2 Input Data Menus (MODEL_D.lNP) 

### The data file for the sample problem is MODEL_D.ERA. Figure 7-4 shows the input data menus for the sample problem. Individual data menus and values are shown for each data block defining the sample problem, exactly as displayed during the input data processing phase ofthe analysis. The specific menus are consistent with the type ofcabinet (top-mount, refrigerator/freezer) and the type of refrigerator cycle (single evaporator, fan-forced). Only data relevant to the particular problem are shown. This data is not normally output for each analysis. However, the user may choose to create and save the menu data as part ofthe documentation for an analysis. The output (MODEL_D.INP) is obtained from the Main Menu ofERA using the "Print Data Menus" or "Write Data Menus to a File" function. 7.3 Intermediate Cabinet Loads Data File (CABINET.DAT) 

### The first executable module ofERA (MENU.EXE) creates an intermediate data file which serves as the input to the cabinet loads program (see Figure 3-1 for the relationship between the executable program modules and the data transfers). As illustrated in Figure 7-5, the structure ofthe intermediate file is designed to facilitate interpretation by the program user. Because ofthe overall structure ofERA, the intermediate data file is not meant to be modified. Program module CAB.EXE will read the file, whose structure will be different for each cabinet type, and perform the cabinet loads analysis. The user may choose to print out this file for documentation purposes.

7-1Table 7- 1. Characteristics cf ®®_
i scio i®nz Height 

### Prototype Refrigerator

61.50 in 156.21 cm Width Depth 

### 30.01 in 76.20 cm 28.25 in 71.76 cm Freezer Volume (approx.) Fresh Food Volume (approx.) 4.60 cu-ft 13.40 cu-ft 

### 130.30 liter 379.50 liter Door Thickness Freezer Wall Thickness Fresh Food Thickness 1.75 in 2.38 in 1.88 in 4.45 cm 6.03 cm 4.76 cm Gasket Heat Loss Air Temperatures 0. Btu/hr-in-F 0.0900 w/m-C

Room Freezer Fresh Food Under Cabinet/Condenser 90.0 F 5.0 F 38.0 F 100.0 F 32.2 C -15.0 C 3.3 C 37.8 C 

### Auxiliary Energy (Cycle Average) Door Flange Heater Liquid Line Liquid Line Mullion Heater 2.75 w 2.75 w Defrost Heat 2.81 w 2.81 w Defrost Timer 1.50 w 

### 1.50 w Refrigeration Cycle 

### Single Evaporator Com pressor

Type 

### Reciprocating EER 

### 5.28 Capacity 865 Btuh 218 kcal/hr 

### Evaporator Area (Air side) 

### 25.2 ft2 2.34 m2 Air Flow 

### 50.0 cfm 23.6 liter/sec. Fan Energy 9.4 w 9.4 w


### Condenser Area (Air side) 9.15 ft2 0.85 m2 Air Flow 90.0 cfm 42.48 liter/sec. Fan Energy 12.0 w 12.0 w Table 7-1. Characteristics of Model D Prototype Refrigerator Dimensions 

### Height Width Depth Freezer Volume (approx.) Fresh Food Volume (approx.) DoorThickness FreezerWall Thickness Fresh Food Thickness Gasket Heat Loss Air Temperatures 

### Room Freezer Fresh Food Under Cabinet/Condenser Auxiliary Energy (Cycle Average) 

### DoorFlange Heater Mullion Heater Defrost Heat Defrost Timer Refrigeration Cycle Compressor 

### Type EER Capacity Evaporator 

### Area (Air side) Airflow FanEnergy Condenser 

### Area (Air side) Airflow Fan Energy 61.50 in 30.01 in 28.25 in

4.60 cu-ft 13.40 eu-ft

1.75 in 2.38 in 1.88 in 0.004 Btu/hr-in-F

90.0F

5.0F 38.0F 100.0 F
Liquid Line 2.75 w 2.81 w 1.50w 156.21 em 76.20 em 71.76 cm 130.30 liter 379.50 liter 4.45 em 6.03 cm 4.76 em 0.0900 w/m-C

32.2C -15.0 C 3.3 C 37.8 C
Liquid Line

2.75 w 2.81 w 1.50w Single Evaporator


### Reciprocating 5.28 865 Btuh 218 kcallhr

25.2 fr 50.0 cfm

9.4 w

9.15 fr 9O.0cfm 12.0w

7-2 2.34 m2 

### 23.6 liter/sec.

9.4 w



### 0.85 m 2 

### 42.48 liter/sec.

12.0w28.25 26.00 k---.625 r- 2.375

19.00

.75 

## 1

Cabinet Width 30.00" 66.00

24.625

39.00

41.75

2.00 

### T 4.50
A1.875 -->

FIGURE 7-1 VERTICAL SECTI O N - 18 FT3 PROTOTYPE M O DEL

(APPR O X. 1/8 SCALE) Evaporator 3 x 8 x 22

7-3 

# r

-------- 28

.25

# --------:1

II-E--I<-26.00------?l

### ~ 

### I<- .625 2.375**~--- ----~--** 

1.75 i-E------ 20.875---+---»\
19.00 15.625 

# "L

Cabinet Width 30.00" 2.50

66.00**~-------+-24.625** --------7:;.1

39.00 1.875 41.75

4.50



# t FIGURE 7-1 VERTICAL SECTION
- 18 FT3 PROTOTYPE MODEL (APPROX. 1/8 SCALE)


### 7-3 Evaporator 3x8x2230.00 2.375

18.125 2.375

---------------------- ;

2.375 1.875

56.00

s.oo Evap. Fan - 4.5" dia Orifice - 4.75" I.D.

Evaporator 3 x 8 x 22 Finned Lgth.

Cabinet Flange 1.00 - 3 Sides

Condenser Air Inlet/Exhaust Approx 24.50 x 2.75



### FIGURE 7-2 FRONT VIEW, CABINET ONLY - 18 FT3 PROTOTYPE MODEL (APPROX. 1/8 SCALE)

7-4 

# r E 

## ----30.00-------:;.;"'1 

# -r 2

.375 --.------,r--



## 66.00**~ ~2.375**  / " I \ I Evap. Fan
- 4.5" dia

___---., Orifice
- 4.75" 1.0. 

# c::...,- --- \ I \ I

" 

### '"**r~:-------------------~~I** Evaporator 3 x8 x22 Finned Lgth. 

# r-z---- I 

# -

# - , , I 

# -

# - , , I 

# -- , ,

### ~

# - I 

# -

# -, , 

# - I , , 

# -- I , 

# - I , , 

# -- I , , 

# --**~** , 

# -- I 

# " 18.125 I - - _**~ ~** , I

# ~/~~

2.375

# OJ**1.875~** <E- 

### _,.. IE- Cabinet Flange 1.00 - 3 Sides

### ~------------------------------~/**~** Condenser Air / 

# " Inlet!Exhaust 

# I Approx 24.50 x 2.75 

# r----\ 

# -z----- 6r
_L...J '-- FIGURE 7-2 FRONT VIEW, CABINET ONLY
- 18 FT3 PROTOTYPE MODEL (APPROX. 1/8 SCALE)


### 7-4r- Inlet
> Outlet (to Accumulator) 

# 1.

8.00 

# 2

3.00 Air Flow 22.00" [111 Fins Spaced .20]

24.50
EVAPORATOR DETAIL Fin & Tube: 24 Tubes - 5/16 OD x .028 Wall Al.

111 Fins - 3 x 8 x Mfrs. Recommended Thickness Note: Circuitry shown is compatible with Peerless mfg. techniques. Other circuitry possible.

Defrost Drain Tray Rests Here



### ---------- U Gas .. In (Rear) Machine Compartment Divider Panel Located Here
i

# C^ x

J 0----0----0----0----0 D----Q----O----O !G "- I Q---- Q---- O ----0-- 2.75 ---U

23.50

CONDENSER DETAIL (WIRE & TUBE - FAN COOLED) Specs: Tubing-1/40D x .028 Wall Steel

Serpentine - 36 Tubes - 16" Overall Width Wires -.046 Dia. - 60 per Side (120 total) - Spaced .200"

FIGURE 7-3 HEAT EXCHANGER DESIGNS 

# I
Tubes marked "X" are not welded.

7-5 

# t Inlet**~**__ ----,- Outlet (to Accumulator)

8.00

### ~ 3.00--l 

# L UAirFlow
22.00" [111 Fins Spaced .20J ---------?j I-E-------- 24.50**-----------~** EVAPORATOR DETAIL Fin & Tube: 24 Tubes
- 5/16 00 x .028 Wall AI. 111 Fins - 3 x 8 x Mfrs. Recommended Thickness Note: Circuitry shown is compatible with Peerless mfg. techniques. Other circuitry possible.

( Machine Compartment Divider Panel Located Here Defrost Drain Tray Rests Here**~** ; 

# (X

'\

- - - -

### ~ - - - - - 7

### "C)""-----;-C)=---~--C)=------C)= X 

# t
Hot Gas.../'\ \ .Jf

## C)----C)----C)----C)--D~ 2.75 In (Rear)
- If '- - - - - - - - - , C)-

...C)

....C)

....C)---.C)

..: C)----C)----C)----C)-- 

# i

# ~IE----- 23.50

# _L_x

# -----7-1>1

CONDENSER DETAIL (WIRE & TUBE
- FAN COOLED) Specs: Tubing
- 1/400 x .028 Wall Steel Serpentine
- 36 Tubes
- 16" Overall Width Wires
- .046 Dia.
- 60 per Side (120 total)
- Spaced .200"

FIGURE 7-3 HEAT EXCHANGER DESIGNS 

### 7-5 Tubes marked "X" are not welded.Multiple Pathways Baseline Protot : Model -D (Top-Mount)

CAB INET TYPE AND OVERALL D IMENSIONS Configuration Type (1-5) 1 Cabinet Height (c) 156.21 Cabinet Width (cm) 76.20 Cabinet Depth * (cm) 71.75 Gasket Width (cm) 1.59 Door Edge Thickness (cm) 4.45 * including door and gasket

CABINET WEDGE DIMENSIONS Freezer Section Wedge Depth (cm) Flange Width (cm) Fresh Food section Wedge Depth (cm) Flange Width (cm) 7.62 3.87 7.62 3.87

REFRIGERATED VOLUME Freezer Section Volume Used by Evap (L) 21.01 Vol Used by Food (L) .00 volume Used by Shelf (L) .00 Net Storage Volume (L) 135.07 Fresh Food Section Vol Used by Evap (L) .00 Volume Used by Food (L) .00 Volume Used by Shelf (L) 18.34 Net Storage Volume (L) 394.74

COMPRESSOR COMPARTMENT DIMENSIONS Top Depth (cm) .00 Bottom Depth (cm) .00 Height (cm) .00

FREEZER INSULATION THICKNESS Top Wall Thickness (cm) 6.03 Side Wall Thickness (cm) 6.03 Back Wall Thickness (cm) 6.03 Door Thickness (cm) 4.45

Figure 7-4. Input Data Menus

7-6 Multiple Pathways Baseline Prototype: Model_D (Top-Mount)

CABINET TYPE AND OVERALL DIMENSIONS Configuration Type (1-5) Cabinet Height (em) Cabinet width (em) Cabinet Depth1< (em) Gasket Width Door Edge Thickness (em) (em)

1< including door and gasket

CABINET WEDGE DIMENSIONS Freezer Section Wedge Depth (em) Flange Width (em) Fresh Food section Wedge Depth (em) Flange Width (em)

REFRIGERATED VOLUME Freezer Section volume Used by Evap (L) Volume Used by Food (L) Volume Used by Shelf (L) Net Storage Volume (L) Fresh Food Section volume Used by Evap (L) Volume Used by Food (L) Volume Used by Shelf (L) Net Storage Volume (L)

COMPRESSOR COMPARTMENT DIMENSIONS TOp Depth (em) Bottom Depth (em) Height (em)

FREEZER INSULATION THICKNESS Top Wall Thickness (em) Side Wall Thickness (em) Back Wall Thickness (em) Door Thickness (em)

Figure 7-4. Input Data Menus 

### 7-6 1 156.21

76.20 71.75

1.59 4.45

7.62 3.87 7.62 3.87

21.01 .00 .00 135.07 .00 .00 18.34 394.74

.00 .00 .00

6.03 6.03 6.03 4.45FREEZER INSULATION RESISTIVITIES Re sistivity (m2-C/W-cm) Top Wall .555 Side Wall .555 Back Wall .555 Door .555 Wedge .555

FRE SH FOOD INSULATION THICKNESS Side Wall Thickness ( cm) 4.76 Back Wall Thickness (cm) 4.76 Bottom Wall Thickness ( cm) 5.08 Door Thickness ( cm) 4.45

FRESH FOOD INSULATION RESISTIVITIES Resistivity (m2-C/W-cm) Side Wall .555 Back Wall .555 Bottom .555 Door .555 Wedge .555

MULLION Distance to Top ( cm) 45.72 Thickness ( cm) 6.35 Resistivity (m2-C/W-cm) .31

AIR AND CABINET TEMPERATURES Room Air ( C) 32.22 Freezer Section (C) -15.00 Fresh Food Section ( C) 3.33 Air Under Cabinet ( C) 37.80 Air Entering Condenser (C) 35.00

DOOR OPENING SCHEDULE Room Relative Humidity ( %) 50.00 Fresh Food Door - #/ Hr .00 Fresh Food Door - Sec Open 15.00 Freezer Door - #/Hr .00 Freezer Door

- Sec Open 20.00 Manual Defrost ( O=N, 1=Y) 0

GASKET HEAT LEAKS (W/M-100C) Fresh Food Section 9.00 Freezer Section 9.00

Figure 7-4. Input Data Menus (continued)



### 7-7 FREEZER INSULATION RESISTIVITIES Resistivity (m2-C/W-em) Top Wall Side Wall Back Wall Door Wedge

FRESH FOOD INSULATION Side Wall Thickness Back Wall Thickness Bottom Wall Thickness Door Thickness THICKNESS (em) (em) (em) (em)

FRESH FOOD INSULATION RESISTIVITIES Resistivity (m2-C/W-em) .555 .555 .555 .555 .555

4.76 4.76 5.08 4.45

Side Wall .555 Back Wall .555 Bottom .555 Door .555 Wedge .555

MULLION Distance to Top (em) Thickness (em) Resistivity (m2-C/W-em)

AIR AND CABINET TEMPERATURES Room Air (C) Freezer Section (C) Fresh Food Section (C) Air Under Cabinet (C) Air Entering Condenser (C)

DOOR OPENING SCHEDULE Room Relative Humidity (%) Fresh Food Door

- #/Hr Fresh Food Door

- Sec Open Freezer Door

- #/Hr Freezer Door

- Sec Open Manual Defrost (O=N, l=Y)

GASKET HEAT LEAKS (W/M-100C) Fresh Food Section Freezer Section



### Figure 7-4. Input Data Menus (continued) 7-7 45.72 6.35

.31

32.22 -15.00 3.33 37.80 35.00

50.00 .00 15.00 .00 20.00 

### o

9.00 9.00DEFROST AND CONTROLS ENERGY USE Automatic Defrost Load Timer Interval (Hr) Heater On-Time (Min) Defrost Heater Energy (W) Other Cycle-Dependent Loads Freezer Section (W) Fresh Food Section (W) Outside Cabinet (W) Constant Electrical Loads* Freezer Section (W) Fresh Food Section (W) Outside Cabinet (W) * See Help Menu <Fl>

ELECTRIC ANTI-S WEAT HEAT Freezer Door Flange Cycle Average Energy (W) Fraction Heat Leak (0-1) Fresh Food Door Flange Cycle Average Energy (W) Fraction Heat Leak (0-1)
Mullion Cycle Average Energy (W) Heat Leak to FZ (0-1) Heat Leak to FF (0-1)

REFRIGERANT LINE ANTI

- SWEAT HEAT Type (1=Vapor, 2=Liquid) Freezer Door Flange Cycle Average Energy (W) Fraction Heat Leak (0-1) Fresh Food Door Flange Cycle Average Energy (W) Fraction Heat Leak (0-1)
Mullion Cycle Average Energy (W) Heat Leak to FZ (0-1) Heat Leak to FF (0-1)

PENETRATION HEAT INPUT Penetration Heat to FZ (W) Penetration Heat to FF (W)

Figure 7-4. Input Data Menus (continued) 10.00 10.00 450.00 .00 .00 1.50 .00 .00 .00

.00 .00

.00 .00

2.75 .50 .25

2

4.00 .30

.00 .00

.00 .00 .00

.00 .00



### 7-8 DEFROST AND CONTROLS ENERGY USE Automatic Defrost Load Timer Interval (Hr) Heater On-Time**(~n)** Defrost Heater Energy (W) Other Cycle-Dependent Loads Freezer Section (W) Fresh Food Section (W) Outside Cabinet (W) Constant Electrical Loads* Freezer Section (W) Fresh Food Section (W) Outside Cabinet (W) * See Help Menu <F1>

ELECTRIC ANTI-SWEAT HEAT Freezer Door Flange Cyc1e Average Energy (W) Fraction Heat Leak (0-1) Fresh Food Door Flange Cycle Average Energy (W) Fraction Heat Leak (0-1) Mullion Cycle Average Energy (W) Heat Leak to FZ (0-1) Heat Leak to FF (0-1)

REFRIGERANT LINE ANTI-SWEAT HEAT Type (1=Vapor, 2=Liquid) Freezer Door Flange Cycle Average Energy (W) Fraction Heat Leak (0-1) Fresh Food Door Flange Cycle Average Energy (W) Fraction Heat Leak (0-1) Mullion Cycle Average Energy (W) Heat Leak to FZ (0-1) Heat Leak to FF (0-1)

PENETRATION HEAT INPUT Penetration Heat to FZ (W) Penetration Heat to FF (W)



### Figure 7-4. InputData Menus (continued) 

### 7-8 10.00 10.00 450.00 .00 .00 1.50

.00 .00 .00

.00 .00

.00 .00
2.75

.50 .25

2
4.00

.30
.00 .00
.00 .00 .00

.00 .00CYCLE DEFINITION Cycle Type (1-4) 1 = Single Evap 2 = Lorenz Cycle 3 = Dual Loop Cycle 4 = Dual Evap Cycle Number Refrigerants (1-3) 1

1 1 = Pure Refrigerant 2 = Bina ry Mixt ure 3 = Te rna ry Mixture

REFRIGERANT CODES Re frigerant Code (1-34) 2

EVAPORATOR DATA Ref Control Option (1-3) 1 1: Evaporator Superheat 2: Interchanger Superheat 3: Evap Exit Quality Refrigerant Superheat (C) .00 Heat Exchanger Type (1-2) 1 1: Cross-Flow 2: Counter-Flow Heat Transfer Type (1-2) 1 1: Forced Convection 2: Free Convection Fan Motor Power ( w) 9.40

EVAPORATOR DATA , CONTINUED Heat Transfer Area (m2) 2.338 Air Flow Rate (L/s) 23.600 Two-Phase U (W/m2 -C) 13.787 Superheat U (W/m2

-C) 5.633 Refr Pressure Drop ( kPa) 7.200

CONDENSER DATA Refrigerant Subcooling (C) .00 Heat Exchanger Type (1,2) 1 1 = Cross-Flow 2 = Counter-Flow Heat Transfer Type (1,2) 1 1 = Forced Convection 2 = Free Convection Fan Motor Power (w) 12.00

Figure 7-4. Input Data Menus (continued)



### 7-9 CYCLE DEFINITION Cycle Type (1-4) 1 

## = Single Evap 2 

## = Lorenz Cycle 3 

## = Dual Loop Cycle 4 

## = Dual Evap Cycle Number Refrigerants (1-3) 1 

## = Pure Refrigerant 2 

## = Binary Mixture 3 

## = Ternary Mixture

REFRIGERANT CODES Refrigerant Code (1-34)

EVAPORATOR DATA Ref Control Option (1-3) 1: Evaporator Superheat 2: Interchanger Superheat 3: Evap Exit Quality Refrigerant Superheat (C) Heat Exchanger Type (1-2) 1: Cross-Flow 2: Counter-Flow Heat Transfer Type (1-2) 1: Forced Convection 2: Free Convection Fan Motor Power (w)

EVAPORATOR DATA, CONTINUED Heat Transfer Area (m2) Air Flow Rate (LIs) Two-Phase U (W/m2-C) Superheat U (W/m2-C) Refr Pressure Drop (kJ?a)

CONDENSER DATA Refrigerant Subcooling (C) Heat Exchanger Type (1,2) 1 ;: Cross-Flow 2 

## = Counter-Flow Heat Transfer Type (1,2) 1 

## = Forced Convection 2 = Free Convection Fan Motor Power (w)



### Figure 7-4. InputData Menus (continued) 7-9 1

1

2

1

3.00 1

1
9.40

2.338 23.600 13.787

5.633 7.200

.00 1

1
12.00CONDENSER DATA, CONTINUED Heat Transfer Area (m2) .85 Air Flow Rate (L/s) 42.48 Sub-Cool U (W/m2-C) 15.43 Two-Phase U (W/m2-C) 19.23 superheat U (W/m2-C) 15.17 Refr Pressure Drop (kPa) 4.72

COMPRESSOR MODEL OPTIONS Compressor Type (1,2) 1 1: Reciprocating 2: Rotary Compressor Model (0,1,2) 1 0: Compressor Map 1: EER and Capacity 2: Efficiency Model Cycling Loss Analysis (0,1) 1 0: No, 1: Yes Cycles per Hour 2.00 Typical: 1.5 to 4.0 Shut-off Valve (0, 1) 0 0: No, 1: Yes

COMPRESSOR DATA Displacement (cc) 6.57 Rated Capacity (kcal/hr) 218.00 Nominal Speed (rpm) 3450.00 Rated EER 5.28 Type of Can Cooling (0, 1) 1 0: Static, 1: Fan-Forced Fractional Speed (0.2-1.0) 1.00 Mass Flow Guess (kg/hr) 5.80

INTERCHANGER DATA Comer Shell Inlet Temp (C) -1.00 (-1 Means Unspecified) Interchanges Effect (0 - 1) Condenser Subcooler .80

Figure 7-4. Input Data Menus (continued)



### 7-10 CONDENSER DATA, COdTlNUED Heat Transfer Area (m2) Air Flow Rate (L/s) Sub-Cool U (W/m2-C) Two-Phase U (W/m2-C) Superheat U (W/m2-C) Refr Pressure Drop (kPa)

COMPRESSOR MODEL OPTIONS Compressor Type (1,2) 1: Reciprocating 2: Rotary Compressor Model (0,1,2) 0: Compressor Map 1: EER and Capacity 2: Efficiency Model Cycling Loss Analysis (0,1) 0: No, 1: Yes Cycles per Hour Typical: 1.5 to 4.0 Shut-off Valve (0, 1) 0: No, 1: Yes

COMPRESSOR DATA Displacement (cc) Rated Capacity (kcal/hr) Nominal Speed (rpm) Rated EER Type of Can Cooling (0, 1) 0: Static, 1: Fan-Forced Fractional Speed (0.2-1.0) Mass Flow Guess (kg/hr)

INTERCHANGER DATA Compr Shell Inlet Temp (C) (-1 Means Unspecified) Interchanger Effect (0

- 1) Condenser Subcooler



### Figure 7-4. InputDataMenus (continued) 7-10 .85 42.48 15.43 19.23 15.17

4.72

1

1

1 2.00 

### o

6.57 218.00 3450.00 5.28 1 1.00 5.80

-1.00

.80Multiple Pathways Baseline Protot : Model -D (Top-Mount)

* * CABINET TYPE

1 TOP-MOUNT RE FRIGERATOR/FRE EZER * CABINET D IMENSIONS 156.2100 CABINET HEIGHT (CM) 76.2000 CABINE T WIDTH (CM) 71.7500 CABINET DEPTH (CH) 7.6200 FREEZER WEDGE (CH) 3.8700 FREEZER FLANGE (CM) 7.6200 FRE SH FOOD WEDGE (CM) 3.8700 FRE SH FOOD FLANGE ( 04 ) 4.4450 DOOR EDGE THICKNESS (CH) 1.5900 GASKET THICKNESS (CM) .0000 COMPRE SSOR 'C TOP DEPTH (CM) .0000 COMPRE SSOR COMPARTMENT BOTTOM DEPTH (CM) .0000 COMPRESSOR COMPARTMENT HEIGHT (CM)
* MULLION DATA 45.7200 DISTANCE TO TOP (CM) 6.3500 THI CKNE SS OF MULLION (CM) * * FREEZER INSULATION THICKNE SS 6.0300 THI CKNE SS OF INSULATION ON TOP OF FREEZER (CM) 6.0300 THICKNESS OF INSULATION ON LEFT SIDE OF FREEZER (CM) 6.0300 THICKNESS OF INSULATION ON RIGHT SIDE OF FREEZER (CM) 4.4450 THI CKNE SS OF INSULATION ON FRONT OF FREEZER (CM) 6.0300 THICKNESS OF INSULATION ON BACK OF FREEZER (CM)
* FRESH FOOD INSULATION THICKNESS 4.7600 THI CKNE SS OF INSULATION ON LEFT SIDE OF FRESH FOOD (CM) 4.7600 THI CKNE SS OF INSULATION ON RIGHT SIDE OF FRESH FOOD (CM) 4.4450 THICKNESS OF INSULATION ON FRONT OF FRESH FOOD (CM) 4.7600 THICKNESS OF INSULATION ON BACK OF FRESH FOOD (CM) 

### *

* COMPRESSOR CAB INET INSULATION THICKNE SS 5.0800 MAXIMUM THICKNESS OF BOTTOM INSULATION FRESH FOOD (CM) 5.0800 THICKNESS OF INSULATION OVER COMPRESSOR (CM)
* REFRIGERATED VOLUME S 21.0100 FREEZER VOLUME USED FOR HEAT EXCHANGERS (L) 135.0700 ADJUSTED FREEZER VOLUME (L) 18.3400 FRESH FOOD VOLUME USED FOR HEAT EXCHANGERS (L) 394.7400 ADJUSTED GENERAL REFRIGERATED VOLUME (L) * * AIR AND CAB INET TEMP ERATURES 32.2200 ROOM TEMPERATURE (C) -15.0000 FREEZER TEMPERATURE (C) 3.3300 FRESH FOOD COMPARTMENT TEMPERATURE (C) 37.8000 UNDERSIDE AIR T EMP ERATURE (C)

Figure 7-5. Intermediate Data: Cabinet Loads Analysis 7-11 Multiple Pathways Baseline Prototype: Model D (Top-Mount)

1< 1< CABINET TYPE

1< 

### '* 1 TOP-MOUNT REFRIGERATOR/FREEZER CABINET 156.2100

76.2000 71.7500

7.6200 3.8700 7.6200 3.8700 4.4450 1.5900

.0000 .0000 .0000 DIMENSIONS CABINET HEIGHT (CM) CABINET WIDTH (CM) CABINET DEPTH (CM) FREEZER WEDGE (CM) FREEZER FLANGE (CM) FRESH FOOD WEDGE (CM) FRESH FOOD FLANGE (CM) DOOR EDGE THICKNESS (CM) GASKET THICKNESS (CM) COMPRESSOR**~OMPARTMENT** TOP DEPTH (CM) COMPRESSOR COMPARTMENT BOTTOM DEPTH (CM) COMPRESSOR COMPARTMENT HEIGHT (CM)

1< MULLION DATA

1< 1<

1< 1<



## '* 45.7200 DISTANCE TO TOP (CM) 6.3500 THICKNESS OF MULLION (CM) FREEZER

6.0300 6.0300 6.0300 4.4450 6.0300 INSULATION THICKNESS

FRESH FOOD

4.7600 4.7600 4.4450 4.7600 THICKNESS OF INSULATION ON TOP OF FREEZER (CM) THICKNESS OF INSULATION ON LEFT SIDE OF FREEZER (CM) THICKNESS OF INSULATION ON RIGHT SIDE OF FREEZER (CM) THICKNESS OF INSULATION ON FRONT OF FREEZER (CM) THICKNESS OF INSULATION ON BACK OF FREEZER (eM) INSULATION THICKNESS THICKNESS OF INSULATION ON LEFT SIDE OF FRESH FOOD (CM) THICKNESS OF INSULATION ON RIGHT SIDE OF FRESH FOOD (CM) THICKNESS OF INSULATION ON FRONT OF FRESH FOOD (CM) THICKNESS OF INSULATION ON BACK OF FRESH FOOD (CM) 

## '* COMPRESSOR CABINET INSULATION THICKNESS 

## '* '*

'* '* 5.0800 MAXLMUM THICKNESS OF BOTTOM INSULATION FRESH FOOD (CM) 5.0800 THICKNESS OF INSULATION OVER COMPRESSOR (CM) REFRIGERATED 21. 0100 135.0700

18.3400 394.7400 VOLUMES FREEZER VOLUME USED FOR HEAT EXCHANGERS (L) AD.roSTED FREEZER VOLUME (L) FRESH FOOD VOLUME USED FOR HEAT EXCHANGERS (L) AD.roSTED GENERAL REFRIGERATED VOLUME (L) AIR AND 32.2200 -15.0000 3.3300 37.8000 CABINET TEMPERATURES ROOM TEMPERATURE (C) FREEZER TEMPERATURE (C) FRESH FOOD COMPARTMENT TEMPERATURE UNDERSIDE AIR TEMPERATURE (C) (C)

Figure 7-5. Intermediate Data: CabinetLoads Analysis 7-11* * INSULATION RESISTIVITIES

.5550 RE SISTIVITY OF REFRIGERATOR INSULATION .5550 .5550 .5550 .5550 .5550 .3150 * G ASKET .0900 .0900 * RESISTIVITY OF FREEZER INSULATION RE SISTIVITY OF REFRIGERATOR WEDGE INSULATION RE SISTIVITY OF FREE ZER WEDGE INSULATION RE SISTIVITY OF REFRIGERATOR DOOR RE SISTIVITY OF FREEZ ER DOOR RE SISTIVITY OF THE MULLION INSULATION S GASEET HEAT LEAK FOR FREEZER COMPARTMENT GASKET HEAT LEAK FOR FRE SH FOOD COMPARTMENT
* DOOR OP ENING SCHEDULES 32.2200 50.0000 .0000 15.0000 

### .0000 20.0000 

### * ROOM TEMPERATURE (C) ROOM RELATIVE HUMIDITY FRE SH FOOD DOOR - OPEN /HR FRE SH FOOD DOOR - SEC OR FREEZER DOOR - OPEN #/HR. FREEZER DOOR - SEC OPEN
* AUXILIARY ENERGY USE (CONSTANT)

.9167 FRE SH FOOD ANTI-SWEAT HEATER (W) 1.8333 FREEZER ANT I-SWEAT HEATER (W) .0000 FRESH FOOD OTHER ENERGY (W) .0000 FREEZER OTHER ENERGY (W) .0000 OUTSIDE CABI NE T (W) * * PENETRATIONS

.0000 FRESH FOOD (W) .0000 FREEZER (W) 

### * * AUXILIARY THERMAL HEAT INPUTS

.6575 FRESH FOOD ELECTRIC ANT I-SWEAT (W) 1.3750 FREEZER ELECTRIC ANTI-SWEAT (W) .0000 FRESH FOOD REFRIGERANT LINE ANTI-SWEAT (W) 1.2000 FREEZER REFRIGERANT LINE ANTI-SWEAT (W) .0000 FRESH FOOD OTHER HEAT SOURCES (W) .0000 FREEZER OTHER HEAT SOURCES (W)

Figure 7-5. Intermediate Data: Cabinet Loads Analysis (continued)
7-12 1< 1< INSULATION RESISTIVITIES .5550 RESISTIVITY OF REFRIGERATOR INSULATION .5550 RESISTIVITY OF FREEZER INSULATION .5550 RESISTIVITY OF REFRIGERATOR WEDGE INSULATION .5550 RESISTIVITY OF FREEZER WEDGE INSULATION .5550 RESISTIVITY OF REFRIGERATOR DOOR .5550 RESISTIVITY OF FREEZER DOOR .3150 RESISTIVITY OF THE MULLION INSULATION 1< 1< GASKET HEAT LEAltS .0900 GASKET HEAT LEAlt FOR FREEZER COMPARTMENT .0900 GASKET HEAT LEAlt FOR FRESH FOOD COMPARTMENT 1< 1< DOOR OPENING SCHEDULES

1< 1<

1< 32.2200 50.0000 .0000 15.0000 .0000 20.0000 AUXILIARY .9167 1.8333

.0000 .0000 .0000 ROOM TEMPERATURE (C) ROOM RELATIVE HUMIDITY (%) FRESH FOOD DOOR

- OPEN 

### I/HR FRESH FOOD 'DooR

- SEC OPEN FREEZER DOOR

- OPEN 

### I/HR FREEZER DOOR

- SEC OPEN ENERGY USE (CONSTANT) FRESH FOOD ANTI-SWEAT HEATER (W) FREEZER ANTI-SWEAT HEATER (W) FRESH FOOD OTHER ENERGY (W) FREEZER OTHl!;R ENERGY (W) OUTSIDE CABINET (W)

1< PENETRATIONS

1< 1< .0000 FRESH FOOD (W) .0000 FREEZER (W) AUXILIARY .6875 1.3750

.0000 1.2000

.0000 .0000 THERMAL HEAT INPUTS FRESH FOOD ELECTRIC ANTI-SWEAT (W) FREEZER ELECTRIC ANTI-SWEAT (W) FRESH FOOD REFRIGERANT LINE ANTI-SWEAT (W) FREEZER REFRIGERANT LINE ANTI-SWEAT (W) FRESH FOOD OTHER HEAT SOURCES (W) FREEZER OTHER HEAT SOURCES (W)



### Figure 7-5. Intennediate Data: CabinetLoads Analysis (continued) 7-127.4 Cabinet Loads Results (CABIN ET.OUT)

The cabinet loads program creates an output file (CAEI T.OUT) which summarizes the input data and the calculated loads . Figure 7-6 illustrates the output for the sample problem. Interpretation of most of the input data is straight forward. The freezer and general refrigerated (fresh food section) volumes are shown to provide a check on the accuracyof the specified input. (A large difference between the calculated and specified net volumes may indicate an input error.) Most of the file CABINET.OUT summarizes the individual cabinet design parameters. Results of the steady state analysis are listed under the heading " HEAT LEAKBREAKDOWN", where components of the net heat load are shown. As discussed earlier, the listed quantities do not yet include the effects of fan heat and of a cold-plate evaporator or hot-wall condenser. The gasket heat loss is a product of the heat leak per unit perimeter, the calculated door perimeter and the room to cabinet temperature difference. The fresh food section always has a negative heat leak across the mullion, since heat flows from the fresh food section to the freezer section. 7.5 Intermediate Cycle D ata File (CYCLE. AT) An ASCII file containing inputs to the cycle model is also created by the menu-driven input processor. An example of the file (CYCLE.DAT) for the sample problem is shown in Figure 7-7. As with the cabinet loads intermediate data file, CYCLE.DAT isnot meant to be edited directly, but is written in a formatted style for ease of interpretation. The actual format will differ with the cycle type and according to the types of evaporator and condenser. Hence, the user should not attempt to run the cycle model directly without using the ERA overall program facilities. Most of the data listed in Figure 7-7 are self explanatory. The section of data entitled "In-wall Evaporator Data" contains correction factors to the cabinet loads that are made in the cycle model to account for the presence of a cold-plate evaporator, or a hot-wall condenser, or both. A code (0, 1) indicates if the evaporator is behind the inner plastic liner. Summary cabined loads output data are appended to the CYCLE.DAT file for use by the cycle model. These parameters enable calculation of the compressor run time, fanenergy, and the daily energy consumption. Each of the cabinet loads data found in Figure 7-7, for the sample problem, can be found in the cabinet loads output report, Figure 7-6. File CYCLE.DAT is essential to run the final executable program, ERACYC.EXE. The ERA program user may wish to print the file out as part of the run documentation. 1.4 cabinet Loads Results (CABINET.OUT} The cabinet loads program creates an output file (CABINET.OUn which summarizes the input data and the calculated loads. Figure 7-6 illustrates the output for the sample problem. Interpretation ofmost ofthe input data is straight forward. The freezer and general refrigerated (fresh food section) volumes are shown to provide a check on the accuracy ofthe specified input. (A large difference between the calculated and specified net volumes may indicate an input error.) Most ofthe file CABINET.OUT summarizes the individual cabinet design parameters. Results ofthe steady state analysis are listed under the heading "HEAT LEAK BREAKDOWN", where components ofthe net heat load are shown. As discussed earlier, the listed quantities do not yet include the effects offan heat and ofa cold-plate evaporator orhot-wall condenser. The gasket heat loss is a product ofthe heat leak per unit perimeter, the calculated door perimeter and the room to cabinet temperature difference. The fresh food section always has a negative heat leak across the mullion, since heat flows from the fresh food section to the freezer section. 1.5 Intermediate Cycle Data File (CYCLE.DAT) An ASCII file containing inputs to the cycle model is also created by the menu-driven input processor. An example ofthe file (CYCLE.DAT) for the sample problem is shown in Figure 7-7. As with the cabinet loads intermediate data file, CYCLE.DAT is not meant to be edited directly, but is written in a formatted style for ease ofinterpretation. The actual format will differ with the cycle type and according to the types of evaporator and condenser. Hence, the user should not attempt to run the cycle model directly without using the ERA overall program facilities. Most ofthe data listed in Figure 7-7 are selfexplanatory. The section ofdata entitled "In-wall Evaporator Data" contains correction factors to the cabinet loads that are made in the cycle model to account for the presence ofa cold-plate evaporator, or a hot-wall condenser, orboth. A code (0, 1) indicates ifthe evaporatoris behind the innerplastic liner. Summary cabined loads output data are appended to the CYCLE.DAT file for use by the cycle model. These parameters enable calculation ofthe compressorrun time, fan energy, and the daily energy consumption. Each ofthe cabinet loads data found in figure 7-7, for the sample problem, can be found in the cabinet loads outputreport, Figure 7-6. File CYCLE.DAT is essential to run the final executable program, ERACYC.EXE. The ERA program user may wish to print the file out as part ofthe run documentation.

7-13Multiple Pathways Baseline Protot : Model -D (Top-Mount)

THERMAL ANALYSIS OF A TOP-MOUNT REFRIGERATOR/FREEZES.

CONFIGURATION TYPE: 1

DIMENSIONAL SPECIFICATIONS
OVERALL: 156.21 HIGH X 76.20 WIDE X 71.75 DEEP FREEZER: THE WEDGE IS 7.62 DEEP THE FLANGES ARE 3.87 WIDE FRESH FDCOMPARTMENT: THE WEDGE IS 7 . 62 DEEP THE FLANGES AliZ, 3
. 87 WIDE THE TOP OF THE MULLION IS 45.72 FROM THE TOP OF THE CAB INET THE MULLION IS 6.35 THICK COMPRESSOR COMPARTMENT D IMENSIONS: TOP DEPTH: .00 CM BOTTOM DEPTH: .00 CM HEIGHT: .00

INSULATION THICKNESS FREEZER TOP 6.03 CM LEFT SIDE 6.03 RIGHT SIDE 6.03 FRONT (DOOR) 4.45 CM BACK 6.03

INSULATION THICKNESS FRESH FOOD LEFT SIDE 4.76 RIGHT SIDE 4.76 FRONT (DOOR) 4.45 BACK 4.76 BOTTOM 5.08 M CM

VOLUME S
FREEZER REFRIGERATED VOLUME CALCULATED 134.98 LITER SPECIFIED SHELF/EVAP 21.01 LITER NET VOLUME 135.07 LITER

GENERAL REFRIGERATED VOLUME CALCULATED 394.79 LITER SPECIFIED SHELF/EVAP 18.34 LITER NET VOLUME 394.74 LITER

TEMP ERATURES ROOM 32.22 DEG C FREEZER CABINET -15.00 DEG C FRESH FOOD CABINET 3.33 DEG C AIR UNDER REFRIGERATOR 37.80 DEG C

Figure 7-6. Cabinet Loads Output

7-14 Mu1tiple pathways Baseline Prototype: Model D (Top-Mount)

THERMAL ANALYSIS OF A TOP-MOUNT REFRIGERATOR/FREEZER
CONFIGURATION TYPE: 1
DIMENSIONAL SPECIFICATIONS OVERALL: 156.21 eM HIGH X 76.20 eM WIDE X 71.75 eM DEEP FREEZER: THE WEDGE IS 7 . 62 eM DEEP THE FLANGES ARE 3.87 eM WIDE FRESH FOOD COMPARTMENT: THE WEDGE IS 7 . 62 eM DEEP THE FLANGES ARE· 3. 87 eM WIDE THE TOP OF THE MULLION IS 45 .72 eM FROM THE TOP OF THE CABINET THE MULLION IS 6 . 35 eM THICK COMPRESSOR COMPARTMENT DIMENSIONS: TOP DEPTH: .00 eM BOTTOM DEPTH: .00 eM HEIGHT: .00 eM
INSULATION THICKNESS FREEZER TOP LEFT SIDE RIGHT SIDE FRONT (DOOR) BACK
INSULATION THICKNESS

VOLUMES FRESH FOOD LEFT SIDE RIGHT SIDE FRONT (DOOR) BACK BOTTOM

FREEZER REFRIGERATED VOLUME CALCULATED SPECIFIED SHELF/EVAP NET VOLUME GENERAL REFRIGERATED VOLUME CALCULATED SPECIFIED

TEMPERATURES ROOM SHELF/EVAP NET VOLUME

FREEZER CABINET FRESH FOOD CABINET AIR UNDER REFRIGERATOR 6.03 eM 6.03 eM 6.03 eM 4.45 eM 6.03 eM

4.76 eM 4.76 eM 4.45 eM 4.76 eM 5.08 eM

134.98 LITER

21.01 LITER 135.07 LITER
394.79 LITER

18.34 LITER 394.74 LITER

32.22 DEG C -15.00 DEG C 3.33 DEG C 37.80 DEG C



### Figure 7-6. Cabinet Loads Output 7-14THERMAL CHARACTERISTICS THERMAL RESISTIVITY FRE SH FOOD CABINET .5550 m2

-C/W-cm FREEZER CAB INET .5550 m2-C/W-cm FRE SH FOOD WEDGE .5550 x2-C/W-c FREE Z ER WEDGE .5550 m2-C/W-cm FRE SH FOOD DOOR .5550 m2 -C/W-cm FREE ZER DOOR .5550 m2-C/W-cm LION .3150 m2-C/W-cm
GASKET HEAT LEAK FREEZER REFRIGERATOR .0900 W/m-C .0900 W/ffi-C

DOOR OPENINGS

AIR TEMPERATURE RELATIVE HUM IDITY FRE SH FOOD COMPARTMENT OPENINGS/HR DURATION OF 1 OPENING FREEZER COMPARTMENT OPENINGS/HR DURATION OF 1 OPENING 32.2 Deg C 50.0 (%)

. 0 /HR 15.0 SECONDS

. 0 /HR 20.0 SECONDS

ANT I-S WEAT HEATERS

FRESH FOOD CABINET .92 W FREEZER CABINET 1.83 W
AUXILIARY ENERGY

FRESH FOOD CABINET .00 W FREEZER CABINET .00 OUTSIDE CABINET .00 W

HEAT LEAK BREAKDOWN FRESH FOOD (W) FREEZER (W) RIGHT WALL 5.53 2.97 LEFT WALL 5.53 2.97 BACK WALL 6.86 3.62 FRONT (DOOR) 7.27 4.69 TOP WALL .00 4.84 BOTTOM 4.31 .00 MULLION -2.60 2.60 WEDGE 2.45 1.94 GASKET 9.12 10.37 OPEN DOOR SENSIBLE LOAD .00 .00 MOISTURE LOAD - CONDENSE .00 .00 MOISTURE LOAD - FROST .00 .00 ANTI-SWEAT HEATER .69 1.38 REFRIGERANT LINE HEAT .00 1.20 PENETRATIONS .00 .00 OTHER THERMAL INPUT .00 .00 TOTAL, 39.16 36.57

Figure 7-6. Cabinet Loads Output (continued)

7-15 THERMAL CHARACTERISTICS THERMAL RESISTIVITY FRESH FOOD CABINET FREEZER CABINET FRESH FOOD WEDGE FREEZER WEDGE FRESH FOOD DOOR FREEZER DOOR .MULLION GASKET HEAT LEAK FREEZER REFRIGERATOR

DOOR OPENINGS AIR TEMPERATURE RELATIVE HUMIDITY FRESH FOOD COMPARTMENT OPENINGS/HR DURATION OF 1 OPENING FREEZER COMPARTMENT OPENINGS/HR DURATION OF 1 OPENING ANTI-SWEAT HEATERS FRESH FOOD CABI;NET FREEZER CABINET AUXILIARY ENERGY FRESH FOOD CABINET FREEZER CABINET OUTSIDE CABINET

HEAT LEAK BREAKDOWN
RIGHT WALL LEFT WALL BACK WALL FRONT (DOOR) TOP WALL BOTTOM MULLION WEDGE GASKET OPEN DOOR SENSIBLE LOAD MOISTURE LOAD

- CONDENSE MOISTURE LOAD

- FROST ANTI-SWEAT HEATER REFRIGERANT LINE HEAT PENETRATIONS OTHER THERMAL INPUT TOTAL .5550 m2-C/W-cm .5550 m2-C/W-cm .5550 m2-C/W-cm .5550 m2-C/W-cm .5550 m2-C/W-cm .5550 m2-C/w-cm .3150 m2-C/W-cm
.0900 W/m-C .0900 W/m-C

32.2 Deg C 50.0 (%) .0 I/HR 15.0 SECONDS .0 I/HR 20.0 SECONDS

.92 W 1.83 W

.00 W .00 W .00 W

FRESH FOOD (W) 5.53 5.53 6.86 7.27

.00 4.31 -2.60

2.45 9.12

.00 .00 .00 .69 .00 .00 .00 39.16



### Figure 7-6. CabinetLoads Output (continued) 7-15 FREEZER (W) 2.97 2.97 3.62 4.69 4.84

.00 2.60 1.94 10.37 .00 .00 .00 1.38 1.20

.00 .00 36.57Multiple Pathways Baseline Prototype: Model-D (Top-Mount)

FILE N : MODEL

D.ERA.
REFRIGERATOR / FRE EZER CONFIGURATION

1 1 REFRIGERATION TYPE (1-5)

CYCLE TYPE ( 1=STANDARD, 2 =L0 Z, 3=DUAL LOOP, 4=DUAL EVAP )

MOIS TURE CONTROL

0 MANUAL DEFROST : 0=NO, 1=YE S
COMPRESSOR OPTIONS

1 COMPRESSOR TYPE (I=RECIPROCATING, 2=ROTARY) 1 COMPRE SSOR ANALYSIS (O=MAP , 1=EER , 2=EFFICIENCY MODEL) 1 CYCLING LOSS ANALYSIS ( 0=NO, 1= S) 2.000 CYCLES PER HOUR 0 SHUT-OFF V .(O=NO, 1= S)

REFRIGERANT CODES (1 - 34):

1 = R11, 2 = R12, 3 = R13, 4 = R13B1, 5 = R14, 6 = R22, 7 = R23, 8 = R113, 9 = R114, 10 = R142b, 11 = R152a, 12 = R216a, 13 = 8125, 14 = R143a, 15 = R134a, 16 = 8123, 17 = C-318, 18 = 8134, 19 = C-C3H6, 20 = R141b 21 = SO2, 22 = 8290, 23 = R600, 24 = R600a, 25 = R32, 26 = R1270, 27 = 8124, 28 = 8115, 29 = CE-216 30 = E-125, 31 = R21, 32 = R143, 33=8218, 34 = E-134

REFRIGERANT DATA

2 CODE ( IR(1)) FOR 1ST REFRIGE RANT 0 CODE ( IR(2)) FOR 2ND REFRIGERANT 0 CODE ( IR(3)) FOR 3RD REFRIGE RANT 1 NUMBER OF COMPONENTS ( MAXIMUM OF THREE) 0.0 MIXTURE INTERACTION PARAME TER

- COMPONENT 1-2 0.0 MI XTURE INTERACTION PARAMETER. - COMP ONENT 1-3 0.0 MI XTURE INTERACTION PARAME TER

- COMPONENT 2-3 1.000 MASS FRACTION OF 1ST REFRIGERANT 0.0 MASS FRACTION OF 2ND REFRIGERANT 0.0 MASS FRACTION OF 3RD REFRIGERANT CONDENSER PARAME TERS

1 HEAT EXCHANGER CONFIGURATION (0=NATURAL CONVECTION, 1=CROSS

- FLOW, 2=COUNTER-FLOW) 35.000 TEMP OF AIR ENTERING CONDENSER (C) 42.476 AIR FLOW RATE ACROSS COIL (L/s) 12.000 FAN POWER (W) 4.720 PRESSURE DROP THROUGH CONDENSER (kPa) 15.167 DESUPERHEATING HEAT TRANSFER CONDUCTANCE, W/m2-C 19.227 TWO

- PHASE HEAT TRANSFER CONDUCTANCE , W/m2-C 15.434 SUBCOOLING HEAT TRANSFER CONDUCTANCE, W/m2-C .849 TOTAL HEAT TRANSFER SURFACE AREA, m2 .000 REFRIGERANT EXIT SUBCOOLING, DEG C 4.000 LIQUID

- LINE ANTI-SWEAT HEAT (W) .000 VAPOR-LINE ANTI

- SWEAT HEAT (W) EVAPORATOR PARAME TERS

1 EVAPORATOR SPECIFICATION (1=EVAP EXIT SUPERHEAT, 2=INTERCHANGER EXIT SUPERHEAT, 3=EVAP EXIT QUALITY 1 HEAT EXCHANGER CONFIGURATION ( 0=NATURAL CONVECTION, 1=CROSS-FLOW , 2 =COUNTER-FLOW) -11.334 TEMP OF AIR ENTERING FRESH FOOD SECTION EVAPORATOR (C)

Figure 7-7. Intermediate Data: Cycle Analysis

7-16 Multiple Pathways Baseline Prototype: Model_D (Top-Mount)

FILE NAME: M.ODEL D.ERA REFRIGERATOR/FREEZER CONFIGURATION 1 REFRIGERATION TYPE (1-5) 1 CYCLE TYPE (1=STANDARD, 2=LORENZ, 3=DUAL LOOP, 4=DUAL EVAP) MOISTURE CONTROL 

### o MANUAL DEFROST: O=NO, 1=YES COMPRESSOR 1 1 1 OPTIONS

2.000 

### o REFRIGERANT CODES 1 = R11, 5 = R14, 9 = R114, 13 = R125, 17 = C-318, 21 = S02, 25 = R32, 29 = CE-216 33 = R218, COMPRESSOR TYPE (1=RECIPROCATING, 2=ROTARY) COMPRESSOR ANALYSIS (O=MAP, 1=EER, 2=EFFICIENCY MODEL) CYCLING LOSS ANALYSIS (O=NO, 1=YES) CYCLES PER HOUR SHUT-OFF VALVE. (O=NO, l=YES) (1 

## - 34) : 2 = R12, 3 = R13, 4 = R13B1, 6 

## = R22, 7 = R23, 8 

## = R113, 10 = R142h, 11 = R152a, 12 = R216a, 14 = R143a, 15 = R134a, 16 = R123, 18 = R134, 19 = C-C3H6, 20 = R141h 22 = R290, 23 = R600, 24 = R600a, 26 = R1270, 27 = R124, 28 = R115, 30 = E-125, 31 = R21, 32 = R143, 34 = E-134 INPUT DATA FOR THE REFRIGERATION SYSTEM REFRIGERANT DATA 2 CODE (IR(1» FOR 1ST REFRIGERANT 

### o CODE (IR(2» FOR 2ND REFRIGERANT 

### o CODE (IR(3» FOR 3RD REFRIGERANT 1 NUMBER OF COMPONENTS (MAXIMUM OF THREE) 0.0 MIXTURE INTERACTION PARAMETER- COMPONENT 0.0 MIXTURE INTERACTION PARAMETER- COMPONENT 0.0 M.IXTURE INTERACTION PARAMETER- COMPONENT 1.000 MASS FRACTION OF 1ST REFRIGERANT 0.0 MASS FRACTION OF 2ND REFRIGERANT 0.0 MASS FRACTION OF 3RD REFRIGERANT CONDENSER PARAMETERS 1-2 1-3 2-3

1 HEAT EXCHANGER CONFIGURATION (O=NATURAL CONVECTION, 1=CROSS-FLOW, 2=COUNTER-FLOW) 35.000 42.476 12.000

4.720 15.167 19.227 15.434 .849 .000 4.000

.000 EVAPORATOR 1 1 -11.334 TEMP OF AIR ENTERING CONDENSER (C) AIR FLOW RATE ACROSS COIL (LIs) FAN POWER (W) PRESSURE DROP THROUGH CONDENSER (kPa) DESUPERHEATING HEAT TRANSFER CONDUCTANCE, W/m2-C TWO-PHASE HEAT TRANSFER CONDUCTANCE, W/m2-C SUBCooLING HEAT TRANSFER CONDUCTANCE, W/m2-C TOTAL HEAT TRANSFER SURFACE AREA, m2 REFRIGERANT EXIT SUBCooLING, DEG C LIQUID-LINE ANTI-SWEAT HEAT (W) VAPOR-LINE ANTI-SWEAT HEAT (W) PARAMETERS EVAPORATOR SPECIFICATION (1=EVAP EXIT SUPERHEAT, 2=INTERCHANGER EXIT SUPERHEAT, 3=EVAP EXIT QUALITY HEAT EXCHANGER CONFIGURATION (O=NATURAL CONVECTION, 1=CROSS-FLOW, 2=COUNTER-FLOW) TEMP OF AIR ENTERING FRESH FOOD SECTION EVAPORATOR (C)


### Figure 7-7. Intermediate Data: Cycle Analysis 7-1623.600 AIR FLOW RATE ACROSS COIL (L/s) 9.400 FAN POWER (W) 7.200 PRESSURE DROP THROUGH FRESH FOOD EVAPORATOR (kPa) 13.787 TWO-PHASE HEAT TRANSFER CONDUCTANCE, W/m2-C 5.633 SUPERHEAT REGION CO t. T CE, W/an2-C 2.338 TOTAL HEAT TRANSFER SURFACE AREA , m2 3.000 REFRIGERANT EXIT SUPERHEAT (C) OR QUALITY (0-1) COMPRE SSOR PARAME TERS 5.800 INIT IAL GUESS FOR REFRIGERANT MASS FLOW RATE (kg/hr) 6.570 COMPRE SSOR DISPLACEMENT , (cc) 218.000 RATED CAPACITY ( kcal/hr) 3450
. 000 NOMINAL SPEED ( rpm) 5.280 RATED EER 1 T YPE OF CAN COOLING (0: STATIC , 1: FAN-FORCED) 1.000 FRACTION AL SPEED (-) -1.000 T EMP. AT COMP. INLET (C) (-1 IF UNSPECIFIED] % ER GER.S

.000 I E GER EXIT SUPERHEAT (C) .800 EFFECT IVENESS OF HIGH T EMP INTERCHANGER IN-WALL EV

APORATOR DATA .000 EV : A/R IN FRESH FOOD SECTION ( OR CABINET WALLS) .000 EV : A/R IN FREEZER SECTION WALLS (IF SEP ARATE SECTION) .000 EVAP : A/R IN MULLION SECTION ( IF PRES ENT ) .000 COND : A/R IN FRESH FOOD SECTION ( OR CABINET WALLS) .000 COND: A/ R IN FREEZER SECTION WALLS ( IF SEPARATE SECTION) .000 BOTH : A/R IN FRESH FOOD SECTION ( OR CABINET WALLS) .000 BOTH : A/R IN FREEZER SECTION WALLS ( IF SEPARATE SECTION) .000 FRACTION OF FRESH FOOD SECTION (OR CABINET WALLS) .000 FRACTION OF FREEZER SECTION WALLS ( INCLUDING MULLION) 0 FF (OR CABINET ) EVAPORATOR BEHIND LINER (O:NO, 1:YES) 0 FZ EVAPORATOR BEHIND LINER ( 0:NO, 1:YES) CYCLE-DEPENDENT ELECTRICAL ENERGY DATA 7.500 CLOSED

-DOOR AUTOMATIC DEFROST (W) .000 FRESH FOOD SECTION .000 FREEZER SECTION 1.500 OUTSIDE CABINET
CABINET LOADS DATA

.92 FRESH FOOD ANTIS WEAT HEATER (W) .00 FRESH FOOD AUXILIARY POWER (W) 1.83 FREEZER ANTISWEAT HEATER (W) .00 FREEZER AUXILIARY POWER (W) .00 OUTSIDE CABINET POWER (W) 32.22 ROOM TEMPERATURE (C) 3.33 FRESH FOOD TEMPERATURE (C) -15.00 FREEZER TEMPERATURE (C) 39.16 FRESH FOOD NET LOAD (W) 36.57 FREEZER LOAD (W) .00 FRESH FOOD DOOR SENSIBLE LOAD (W) .00 FRESH FOOD DOOR CONDENSATION LOAD (W) .00 FRESH FOOD DOOR FROST LOAD (W) .00 FREEZER DOOR SENSIBLE LOAD (W) .00 FREEZER DOOR CONDENSATION LOAD (W) .00 FREEZER DOOR FROST LOAD (N) .00 FRESH FOOD PENETRATIONS (W) .00 FREEZER PENETRATIONS (W) .69 FRESH FOOD HEATERS AND CONTROLS (W) 1.38 FREEZER HEATERS AND CONTROLS (W) .00 FRESH FOOD REFRIGERANT LINE (W) 1.20 FREEZER REFRIGERANT LINE (W) 2.60 MULLION HEAT LOAD (W)

Figure 7-7. Intermediate Data: Cycle Analysis (continued) 7-17 23.600

9.400 7.200 13.787

5.633 2.338 3.000 AIR FLOW RATE ACROSS COIL (Lis) FAN POWER (W) PRESSURE DROP THROUGH FRESH FOOD EVAPORATOR (kPa) TWO-PHASE HEAT TRANSFER CONDUCTANCE, W/m2-C SUPERHEAT REGION**COND~~TANCE,** W/m2-C TOTAL HEAT TRANSFER SURFACE AREA, m2 REFRIGERANT EXIT SUPERHEAT (C) OR QUALITY (0-1) COMPRESSOR 5.800 6.570 218.000 3450.000 5.280 PARAMETERS

1 1.000 -1.000 INTERCHANGERS INITIAL GUESS FOR REFRIGERANT MASS FLOW RATE (kg/hr) COMPRESSOR DISPLACEMENT, (cc) RATED CAPACITY (kcal/hr) NOMINAL SPEED (rpm) RATED EER TYPE OF CAN COOLING (0: STATIC, 1: FAN-FORCED) FRACTIONAL SPEED (-) TEMP. AT COMPo INLET (C) [-1 IF UNSPECIFIED] .000 INTERCHANGER EXIT SUPERHEAT (C) .800 EFFECTIVENESS OF HIGH TEMP INTERCHANGER IN-WALL EVAPORATOR DATA .000 EVAP: AIR IN FRESH FOOD SECTION (OR CABINET WALLS) .000 EVAP: AIR IN FREEZER SECTION WALLS (IF SEPARATE SECTION) .000 EVAP: AIR IN MULLION SECTION (IF PRESENT) .000 COND: AIR IN FRESH FOOD SECTION (OR CABINET WALLS) .000 COND: AIR IN FREEZER SECTION WALLS (IF SEPARATE SECTION) .000 BOTH: AIR IN FRESH FOOD SECTION (OR CABINET WALLS) .000 BOTH: AIR IN FREEZER SECTION WALLS (IF SEPARATE SECTION) .000 FRACTION OF FRESH FOOD SECTION (OR CABINET WALLS) .000 FRACTION OF FREEZER SECTION WALLS (INCLUDING MULLION) 

### o FF (OR CABINET) EVAPORATOR BEHIND LINER (0 :NO, 1 :YES) 

### o FZ EVAPORATOR BEHIND LINER (O:NO, l:YES) CYCLE-DEPENDENT ELECTRICAL ENERGY DATA 7.500 CLOSED-DOOR AUTOMATIC DEFROST (W)

.000 FRESH FOOD SECTION .000 FREEZER SECTION 1.500 OUTSIDE CABINET CABINET LOADS .92 .00 1.83

.00 .00 32.22

3.33 -15.00

39.16 36.57 .00 .00 .00 .00 .00 .00 .00 .00 .69 1.38

.00 1.20 2.60 DATAFRESH FOOD ANTI SWEAT HEATER (W) FRESH FOOD AUXILIARY POWER (W) FREEZER ANTISWEAT HEATER (W) FREEZER AUXILIARY POWER (W) OUTSIDE CABINET POWER (W) ROOM TEMPERATURE (C) FRESH FOOD TEMPERATURE (C) FREEZER TEMPERATURE (C) FRESH FOOD NET LOAD (W) FREEZER LOAD (W) FRESH FOOD DOOR SENSIBLE LOAD (W) FRESH FOOD DOOR CONDENSATION LOAD (W) FRESH FOOD DOOR FROST LOAD (W) FREEZER DOOR SENSIBLE LOAD (W) FREEZER DOOR CONDENSATION LOAD (W) FREEZER DOOR FROST LOAD (W) FRESH FOOD PENETRATIONS (W) FREEZER PENETRATIONS (W) FRESH FOOD HEATERS AND CONTROLS (W) FREEZER HEATERS AND CONTROLS (W) FRESH FOOD REFRIGERANT LINE (W) FREEZER REFRIGERANT LINE (W) MULLION HEAT LOAD (W)



### Figure 7-7. Intennediate Data: Cycle Analysis (continued) 7-177.6 Cycle Analysis Results (CYCLE. U

Program ERACYC.EXE reads the cycle data, CYCLE.DAT, and then simulates the steady state thermodynamic cycle. The calculations assume constant operation of the compressor. Transient effects are, by definition, missing, From the evaporator capacity, the fan power, and the cabinet loads, the compressor run time is estimated. A correction to the net compressor power to account for cycle transients is estimated and utilized when determining the daily energy consumption (see Appendix A). Figure 7-8 lists the output from the cycle program (CYCLE.OUT). Thermodynamic state points are shown for 12 locations about the circuit. In the instance of the single evaporator cycle only one subcooling heat exchanger and one evaporator are present. Temperatures and thermodynamic data are shown for the refrigerant at each state point. Temperature data are also shown for the air in the instance of a fan forced heat exchanger. The air temperatures are shown as if counter-flow heat exchangers were used, even if the flow is cross-flow. The important parameter is the product of the air flow rate, specific heat, and air temperature change across the heat exchanger. This product must agree with the mass flow - enthalpy difference product of the refrigerant across the heat exchanger. The listed evaporator capacity ignores the effects of fan heat, which are taken into account in another manner. Capacities and power are shown in units of kJ/hr and watts. The data listed in the cycle output will be dependent on the type of compressor model selected. For the sample case, the compressor was described in terms of the capacity, EER and displacement in a standard calorimeter test configuration. ERA estimates the values for the adiabatic compression efficiency, combined motor-pump efficiency and shell loss from built-in algorithms (see Appendix B). The estimated clearance volume is determined from the calorimeter data for capacity (and, hence, refrigerant mass flow). These are printed, followed by "(Compressor EER Model)," to indicate the source of the compressor model data. The data values may be used for a subsequent analysis using the compressor efficiency model option, if desired. The output also lists the calculated air flow distribution between the fresh food and freezer sections. A change in the cabinet or cycle design may result in significant changes in the required distribution of refrigerated air. For example, use of a variable capacity compressor may require a means of active baffle control to ensure that both cabinet temperatures are maintained. The second page of CYCLE.OUT gives a simple diagram of the cycle, with calculated refrigerant temperatures. 7.6 Cycle Analysis Results (CYCLE.OUT) Program ERACYC.EXE reads the cycle data, CYCLE.DAT, and then simulates the steady state thermodynamic cycle. The calculations assume constant operation ofthe compressor. Transient effects are, by definition, missing, From the evaporator capacity, the fan power, and the cabinet loads, the compressorrun time is estimated. A correction to the net compressorpowerto account for cycle transients is estimated and utilized when determining the daily energy consumption (see Appendix A). Figure 7-8 lists the output from the cycle program (CYCLE.OUT). Thermodynamic state points are shown for 12 locations about the circuit. In the instance of the single evaporator cycle only one subcooling heat exchanger and one evaporator are present. Temperatures andthermodynamic data are shown for the refrigerant at each state point. Temperature data are also shown for the air in the instance ofa fan forced heat exchanger. The air temperatures are shown as ifcounter-flow heat exchangers were used, even ifthe flow is cross-flow. The importantparameteris the product ofthe air flow rate, specific heat, and air temperature change across the heat exchanger. This product must agree with the mass flow

- enthalpy difference product ofthe refrigerant across the heat exchanger. The listed evaporator capacity ignores the effects offan heat, which are taken into account in another manner. Capacities and power are shown in units of

### kJ/hr and watts. The data listed in the cycle output will be dependent on the type ofcompressor model selected. For the sample case, the compressor was described in terms ofthe capacity, EER and displacementin a standardcalorimeter test configuration. ERA estimates the values for the adiabatic compression efficiency, combinedmotor-pump efficiency and shell loss from built-in algorithms (see Appendix B). The estimated clearance volume is determined from the calorimeter data for capacity (and, hence, refrigerant mass flow). These are printed, followed by "(CompressorEER Model)," to indicate the source ofthe compressor model data. The data values may be used for a subsequent analysis using the compressor efficiency model option, ifdesired. The output also lists the calculated airflow distribution between the fresh food and freezer sections. A change in the cabinet or cycle design may result in significant changes in the required distribution ofrefrigerated air. For example, use ofa variable capacity compressormay require a means ofactive baffle control to ensure that both cabinet temperatures are maintained. The second page ofCYCLE.OUT gives a simple diagram ofthe cycle, with calculated refrigerant temperatures.

7-18RUN AT 10:51:13 ON 18 MAR 1993

STANDARD ONE EV APORATOR CYCLE

THE REFRIGERANT MIXTURE CONSISTS OF 100.% R12

OUTPUT RESULTS

STATE T ( C) P H V S XL XV XQ AIR REF (KPA) ( / ) (M3 /KG) (KJ / KG-C) (MASS FRAC ) 1 COMP IN N/A 32.4 125.2 202.0 .1639 .799 .000 1.000 1.000 2 COMP DIS N/A 77.8 1258.9 218.3 .0160 .702 .000 1.000 1.000 3 COND IN 39
. 8 77.9 1259.1 218.3 .0186 .715 .000 1.000 1.000 4 COND DEW N/A 51
. 5 1258.3 198.1 .0137 .643 .000 1.000 1.000 5 COND BUB N/A 51.3 1254.4 77.8 .0008 .272 1.000 .000 .000 6 COND OUT 35.0 51.3 1254.1 77.8 .0008 .272 1.000 .000 .000 7 LIQ LINE N/A 45.2 1254.1 71.4 .0008 .252 1
. 000 .000 .000 8 SUBCOOL N/A 12.9 1254.1 39.5 .0007 .146 1.000 .000 .000 9 EVAP IN -19
. 1 -23.2 132.4 39.5 .0262 .190 1.000 1.000 .206 10 EV AP DEW N/A -24
. 5 125.4 168.5 .1301 .678 .000 1.000 1.000 11 EVAP OUT -12.3 -21.6 125.2 170.1 .1321 .685 .000 1.000 1.000 12 HX OUT N/A 32.4 125.2 202.0 .1639 .799 .000 1.000 1.000
CYCLE PERFORMANCE SUMMARY
EVAPORATOR CAPACITY--------------- 788.9 KJ/HR (219.1 W) CONDENSER HEAT REJECTION RATE ---- 848.8 KJ/HR (235.8 W) COMPRESSOR POWER REQUI REMENT ----- 563
. 0 KJ/HR ( 156.4 W) COEFFICI ENT OF PERFORMANCE ------- 1 401 . FRACTION AIR TO FRESH FOOD -------
. 150 (SINGLE EVAPORATOR CYCLE)
EST IMATED COMPRESSION EFFICIENCY

- 1.348 (COMPRESSOR EER MODEL) EST IMATED MOTOR.-PUMP EFFICIENCY

- . 449 (COMPRESSOR EER MODEL) EST IMATED CLEARANCE VOLUME - .022 (COMPRESSOR EER MODEL) ESTIMATED SHELL LOSS

- . 825 (COMPRESSOR EER MODEL) EST IMATED DISC TUBE HEAT LOSS -
. 387 (COMPRESSOR EER MODEL)
HEAT EXCHANGER PERFORMANCE SUMMARY
EXCHANGER EFFECTIVENESS , % SUBCOOLED FRACTION, % SUPERHEATED FRACTION, %
EVAPORATOR

--------- 96.2 CONDENSER

---------- 89.4 N/A 2.5 .0 11.0
COMPRESSOR PERFORMANCE SUMMARY
REFRIGERANT MAS S FLOW RATE

----- 6.040 KG/HR VOLUMETRIC EFFICIENCY

---------- .772 PRESSURE RATIO

----------------- 10.05 SUCTION PORT T EMPERATURE

------- 49.9 C DISCHARGE PORT T EMPERATURE
----- 126.2 C DISCHARGE SUPERHEAT

------------ 26.4 C

Figure 7-8. Cycle Analysis Output



### 7-19 RUN AT 10:51:13 ON 18 MAR 1993 STANDARD ONE EVAPORATOR CYCLE
THE REFRIGERANT MIXTURE CONSISTS OF 100.% R12

STATE T AIR 1 COMP IN N/A 2 COMP DIS N/A 3 COND IN 39.8 4 COND DEW N/A 5 COND BUB N/A 6 COND OUT 35.0 7 LIQ LINE N/A 8 SUBCOOL N/A 9 EVAP IN -19.1 10 EVAP DEW N/A 11 EVAP OUT -12.3 12 ax OUT N/A OUTPUT RESULTS

(C) P H V

REF (KPA) (KJ/KG) (M3/KG) 32.4 125.2 202.0 .1639 17.8 1258.9 218.3 .0160 17.9 1259.1 218.3 .0186 51.5 1258.3 198.1 .0137 51.3 1254:4 77 .8 .0008 51.3 1254.1 77.S .0008 45.2 1254.1 71.4 .0008 12.9 1254.1 39.5 .0007 -23.2 132.4 39.5 .0262 -24.5 125.4 168.5 .1301 -21.6 125.2 170.1 .1321

32.4 125.2 202.0 .1639 CYCLE PERFORMANCE SUMMARY 788.9 KJ/HR 848.8 KJ/HR 563.0 KJ/HR 1.401 S (KJ/KG-C) .799 .702 .715 .643 .272 .272 .252 .146 .190 .678 .685 .799

(219.1 W) (235.8 W) (156.4 W) XL XV (MASS FRAC) .000 1.000 .000 1.000 .000 1.000 .000 1.000 1.000 .000 1.000 .000 1.000 .000 1.00,0 .000 1.000 1.000

.000 1.000 .000 1.000 .000 1.000

EVAPORATOR CAPACITY--------------- CONDENSER HEAT REJECTION RATE

---- COMPRESSOR POWER REQUIREMENT

----- COEFFICIENT OF PERFORMANCE

------- FRACTION AIR TO FRESH FOOD

------- .150 (SINGLE EVAPORATOR CYCLE) ESTIMATED COMPRESSION EFFICIENCY

- ESTIMATED MOTOR-PUMP EFFICIENCY

- ESTIMATED CLEARANCE VOLUME ESTIMATED SHELL LOSS ESTIMATED DISC TUBE HEAT LOSS 1.348 .449 .022 .825 .387 (COMPRESSOR EER MODEL) (COMPRESSOR EER MODEL) (COMPRESSOR EER MODEL) (COMPRESSOR EER MODEL) (COMPRESSOR EER MODEL) HEAT EXCHANGER PERFORMANCE SUMMARY XQ
1.000 1.000 1.000 1.000

.000 .000 .000 .000 .206 1.000 1.000 1.000

EXCHANGER EFFECTIVENESS, % SUBCOOLED FRACTION, % SUPERHEATED FRACTION, % EVAPORATOR

--------- 96.2 CONDENSER

---------- 89.4 N/A .0 COMPRESSOR PERFORMANCE SUMMARY REFRIGERANT MASS FLOW RATE

----- VOLUMETRIC EFFICIENCY

---------- PRESSURE RATIO

----------------- SUCTION PORT TEMPERATURE

------- DISCHARGE PORT TEMPERATURE

----- DISCHARGE SUPERHEAT

------------ 6.040 KG/HR .772 10.05

49.9 C 126.2 C

26.4 C



### Figure 7-8. Cycle Analysis Output 7-19 2.5 11.0I 77.9 +-----------+ Condenser - ------------ 77.8
I I I I-I 1 Conpr I 563. I I 45.2 1 32
. 4 32.4 I

I I 11 12.9 I 1 -21.6 I I 788. KJ/HR 1 -23.2 1 I 1 +--X--------I Evaporator I-----------+

I I

Figure 7-8. Cycle Analysis Output (continued) KJ/HR



### 7-20 848. KJ/HR. 51.3 I I 77.9 

### +-----------+ Condenser 

### +-----------+ 77.8 I 1

______________________, __1

__ I I I 45.2 I 32.4 I 

### _1-

_ i I I 

### me I**I--,-~I** 12.9 I -21.6 I Compr 563. KJ/HR. 32.4

I I I '788. KJ/HR. I I I I -23.2 I I I 

### +--x--------I Evaporator 

### 1-----------+ 

# ,----------------------1

Figure 7-8. Cycle Analysis Output (continued) 7-20

### 7.7 Energy Consumption Results (E .OU

Output file ERA.OUT provides a summary of the calculated loads and daily energy consumption (Figure 7-9). It also gives information on the type of refrigerator cabinet, thermodynamic cycle, and refrigerant. For a single evaporator, the cabinet set points are fixed and the air baffle is adjusted (mathematically) by the model to achieve the cabinet temperatures

. For some cases, this temperature may not be fixed, but may be dependent on the cabinet design and the design of the refrigeration cycle (for example, with a Lorenz cycle using natural convection evaporators). In this instance the output will show both the desired and actual cabinet temperatures. A number of heat load parameters appear in the summary cabinet loads table in addi-tion to the wall conduction loads

. These include : electric defrost, penetrations, heaters and controls , fan heat, refrigerant line heat, in-wall evaporator, in-mullion evaporator, and in

-wall condenser: ® Electric Defrost -- total heat associatd with defrost, including scheduled defrostenergy from closed door test and from frosting effects associated with door openings ® Penetrations -- defined heat leaks not directly associated with controls or heaters ® Heaters and Controls -- sum of "constant` and "cycle-dependent " controls and heaters ® Fan Heat --calculated on the basis of compressor run time and fan power ® Refrigerant Line Heat -- heat from a vapor line or a liquid line used for anti-sweat purposes that enters the cabinet around door flanges and the mullion ® In-Wall Evaporator -- additional heat flow into the cabinet from the presence of a cold-plate evaporator, not accounted for in the cabinet loads analysis CABINET.- OUT fileIn-Mullion Evaporator -- added cooling of the fresh food section due to the presence of an evaporator in the mullion section of the freezer. The load will be negative (cooling)In-Wall Condenser -- added cabinet heat load due to the presence of a hot-wall condenser. The total values shown for the cabinet section are the hourly average loads which must be removed by the refrigeration system. Two cooling capacities are shown: 1) evaporator load, and 2) net capacity. Normally these two quantities are the same. If a cold-plate evaporator is used, however, the total evaporator load will be higher than the net capacity due to the heat going directly to the back of the evaporator through the insulation. 7.7 Energy Consumption Results (ERA.OUT) Output file ERA.OUTprovides a summary ofthe calculated loads and daily energy consumption (Figure 7-9). It also gives infonnation on the type ofrefrigerator cabinet, thennodynamic cycle, and refrigerant. Fora single evaporator, the cabinet setpoints are fixed and the air baffle is adjusted (mathematically) by the model to achieve the cabinet temperatures. For some cases, this temperature may not be fixed, but may be dependent on the cabinet design and the design ofthe refrigeration cycle (for example, with a Lorenz cycle using natural convection evaporators). 

### In this instance the output will show both the desired and actual cabinet temperatures. A number ofheat loadparameters appear in the summary cabinet loads table in addition to the wall conduction loads. These include: electric defrost, penetrations, heaters and controls, fan heat, refrigerant line heat, in-wall evaporator, in-mullion evaporator, and in-wall condenser:

• Electric Defrost

-- total heat associatd with defrost, including scheduled defrost energy from closed door test and from frosting effects associated with door openings

• Penetrations

-- defined heat leaks not directly associated with controls orheaters

• Heaters and Controls

-- sum of "constant' and "cycle-dependent" controls and heaters " Fan Heat --calculated on the basis ofcompressorrun time and fan power " Refrigerant Line Heat

-- heat from a vapor line or a liquid line used for anti-sweat purposes that enters the cabinet around door flanges and the mullion " In-Wall Evaporator

-- additional heat flow into the cabinet from the presence ofa cold-plate evaporator, not accounted for in the cabinet loads analysis CABINET.- OUT file

• In-Mullion Evaporator

-- added cooling ofthe fresh food section due to the presence ofan evaporator in the mullion section of the freezer. The load will be negative (cooling)

• In-Wall Condenser

-- added cabinet heat load due to the presence ofa hot-wall condenser. The total values shown for the cabinet section are the houdy average loads which must be removed by the refrigeration system. Two cooling capacities are shown: 1) evaporator load, and 2) net capacity. Nonnally these two quantities are the same. Ifa cold-plate evaporator is used, however, the total evaporator load will be higher than the net capacity due to the heat going directly to the back ofthe evaporator through the insulation.



### 7-21RUN NUMBER : FILE N : MODEL D.E

S Y RESULTS Multiple Pathways Baseline Protot : Model -D (Top-Mount)

TOP-XOUNT REFRIGERATOR! F EZ
STANDARD SINGLE EVAPORATOR CYCLE DATE: 03/18/93 T : 10:51

REFRIGERANT DATA FRE SH FOOD FREEZER R12 R12

SET POINTS ( C) 3.330 -15.000
CABINE T LOADS (W)
CONDUCTION FRESH FOOD 38.470 FREEZER 33.990 TOTAL 72.460 DOOR OPENINGS
. 000 .000 .000 FROSTING . 000 .000 .000 ELEC DEFROST
. 000 2
. 805 2.805 PENETRATIONS .000 .000 .000 HEATERS & CONTROLS .690 1.380 2.070 FAN HEAT .526 2.989 3.515 REFRIGERANT LINE . 000 1
. 200 1.200 IN WALL EVAP .000 .000 .000 IN MULLION EVAP .000 .000 .000 IN WALL COND
. 000 .000 .000
TOTAL LOADS 39.686 42
. 364 82.050

REFRIGERATION CYCLE
EVAP LOAD ( W) 219.135 NET CAPACITY (W) 219.135 MASS FLOW ( KG/HR) 6.040 COP - STEADY STATE 1.401 COP - CYCLING 1.373 DUTY CYCLE .374
COMPRESSOR (KWH/ DAY) 1.433 FANS ( / DAY) .192 ELECTRONICS ( KWH /DAY) .000 HEATERS & CONTROLS ( KWH/DAY) .079 DEFROST (KWH/ DAY) .067 TOTAL ENERGY USE (KWH / DAY) 1.772

Figure 7-9. Energy Consumption Results



### 7-22 RUN NUMBER: FILE NAME: MODEL D. ERA

SUMMARY RESULTS Multiple Pathways Baseline Prototype: Model D (Top-Mount)

TOP-MOUNT REFRIGERATOR/FREEZER STANDARD SINGLE EVAPORATOR CYCLE REFRIGERANT DATA

SET POINTS (C) CABINET LOADS (W) CONDUCTION DOOR OPENINGS FROSTING ELEC DEFROST PENETRATIONS HEATERS & CONTROLS FAN HEAT REFRIGERANT LINE IN WALL EVAP IN-MULLION EVAP IN-WALL COND TOTAL LOADS

REFRIGERATION CYCLE EVAP LOAD (W) NET CAPACITY (W) MASS FLOW (KG/HR) COP

- STEADY STATE COP

- CYCLING DUTY CYCLE COMPRESSOR (KWH/DAY) FANS (KWH/DAY) ELECTRONICS (KWH/DAY) HEATERS , CONTROLS (KWH/DAY) DEFROST (KWH/DAY) TOTAL ENERGY USE (KWH/DAY) FRESH FOOD R12 3.330

FRESH FOOD

38.470 .000 .000 .000 .000 .690 .526 .000 .000 .000 .000 39.686

219.135 219.135 6.040 1.401 1.373

.374 1.433

.192 .000 .079 .067 1.772 FREEZER R12 -15.000

FREEZER

33.990 .000 .000 2.805

.000 1.380 2.989 1.200

.000 .000 .000 42.364



### Figure 7-9. Energy Consumption Results 7-22 DATE: 03/18/93 TIME: 10:51

TOTAL 72.460 .000 .000 2.805

.000 2.070 3.515 1.200

.000 .000 .000 82.050The refrigerant mass flow rate and steady state COP are taken directly from the cycle

output (Figure 7-8). Duty cycle (compressor run time fraction) is calculated by the ratio of the hourly average cabinet load and the instantaneous evaporator capacity. Cycling losses are established from the duty cycle (see Appendix B). The total daily energy consumption is the sum of the following: ® Compressor energy -- compressor power times duty cycle ® Fan energy -- fan power times duty cycle ® Electronics -- variable speed drive electronics loss ® Heaters and controls -- auxiliary electrical energy ® Defrost -- total defrost energy, including frosting effects associated with open doors For the sample problem, a 1993 prototype 18 cu-ft top-mount refrigerator/freezer, the daily energy consumption is 1.77 kWh, yielding an annual consumption of 647 kWh.Figure 7-9 shows the summary output for a single evaporator cycle using a pure refrigerant. Alterations to this file will appear for the other refrigeration cycles. The refrigerant mass flow rate and steady state COP are taken directly from the cycle output (Figure 7-8). Duty cycle (compressor run time fraction) is calculated by the ratio ofthe hourly average cabinet load and the instantaneous evaporator capacity. Cycling losses are established from the duty cycle (see Appendix B). The total daily energy consumption is the sum ofthe following: " Compressor energy -- compressorpower times duty cycle

.. Fan energy -- fan power times duty cycle

.. Electronics

-- variable speed drive electronics loss

• Heaters and controls

-- auxiliary electrical energy

e Defrost

-- total defrost energy, including frosting effects associated with open doors For the sample problem, a 1993 prototype 18 cu-ft top-mount refrigerator/freezer, the daily energy consumption is 1.77 kWh, yielding an annual consumption of647 kWh. Figure 7-9 shows the summary output for a single evaporatorcycle using a pure refrigerant. Alterations to this file will appear for the otherrefrigeration cycles.

7-23

### 8.0 SUGGESTIONS FOR USING

8.1 Fite Naming Conventions The ERA menu-driven input processor is capable of generating and storing a large number of data files in a short time. Each file name can have up to 8 characters and must have extension ERA. Since each file has a 5-line title block, the file can be read into ERA and edited to determine the contents of the file. A simpler means of distinguishing between the various files is to adopt a file naming convention. One stegy is illustrated in Appendix C, which lists files prepared for themultiple pathways study [5]. For example, Path I is based on the Model D refrigerator/freezer design. The path contains a baseline 1991 model (MODEL_D), a baseline 

### 1993 model using C- 134a refrigerant and an HCFC blown foam (D_1993), and 10 additional steps: Step Change File Name 1 Cut gasket loss 25% D1_01G25 

### 2 Cut gasket loss 50% total D1_02G50 3 Liquid line mullion anti-sweat heat Dl_03LLM 4 5.5 EER Compressor D1_04C 

### 5 Add 3/4 inch insulation to door D 1_O5DRI 6 crocell insulation D1 06MCI 7 Add 1 inch insulation everywhere D1_071N1 

### 8 Adaptive defrost Dl_08ADF 9 ECM evaporator fan D 1_09DCE 10 ECM condenser fan D1_10DCC The particular naming strategy adopted here is straightforward: the first letter is the Model (D), the next two are the path identifier, then the step in path (1-10), followed by a two or three letter code that identifies the component change. ERA allows the use of special characters, such as the underline, slash and numbers, tocreate a meaningful name for each file. There are no fixed rules for naming conventions. 

### 8.2 Internal Documentation of the Case The user has access to a full screen editor in the menu program to create a 5 line new title

. Each line contains up to 68 characters. When making many runs, it will be important to fully describe the run using the built

-in editor

. The run title is then reproduced on the summary output file (ERA.OUT) along with the name of the data file and the time the run was made. 8.0 SUGGESTIONS FOR USING ERA 8.1 File Naming Conventions The ERA menu-driven input processor is capable ofgenerating and storing a large number ofdata files in a short time. Each file name can have up to Scharacters and must have extension .ERA. Since each file has a 5-line title block, the file can be read into ERA and edited to determine the contents ofthe file. A simpler means ofdistinguishing between the various files is to adopt a me naming convention. One strategy is illustrated in Appendix C, which lists mes prepared for the multiple pathways study [5]. For example, Path 1is based on the Model D refrigerator/freezer design. The path contains a baseline 1991 model (MODEL_D), a baseline 1993 model using HFC-134arefrigerant and an HCFC blown foam (0_1993), and 10 additional steps: 

### Step Change FileName

1 1 Cut gasket loss 25% Dl_01G25**~** Cut gasket loss 50% total Dl_02G50 3 Liquid line mullion anti-sweat heat Dl_03LLM 4 5.5 EER Compressor Dl_04CMP 5 Add 3/4 inch insulation to door Dl_05DRI 6 Microcell insulation Dl_06MCI 7 Add 1inch insulation everywhere DC07INI S Adaptive defrost Dl_0SADF 

### 9 ECMevaporatorfan Dl_09DCE 10 ECM condenser fan Dl_lODCC Theparticular naming strategy adopted here is straightforward: the ftrst letteris the Model (D), the next two are the path identifier, then the step in path (1-10), followed by a two or three letter code that identifies the component change. ERA allows the use of special characters, such as the underline, slash and numbers, to create a meaningful name for each me. There are no fixed rules for naming conventions. 

### 8.2 Internal Documentation ofthe Case The user has access to a full screen editorin the menu program to create a 5 line new title. Each line contains up to 68 characters. When making many runs, it will be important to fully describe the run using the built-in editor. The run title is then reproduced on the summary output file (ERA.OUT) along with the name ofthe data me and the time the run was made.

8-1Note that E RA will overwrite the outputfiles with each new run. Hence, when making multiple runs, the output data should be either saved under a new name or printed after each analysis. 8.3 Summary Output Form ERA contains a blank form that can be used to summarize the results. An example isshown in Figure 8-l. Copies of this form can be made by printing out file SUMMARY. Note that ERA will overwrite the output files with each new run. Hence, when making multiple runs, the output data should be either saved under a new name or printed after each analysis. 8.3 Summary Output Form ERA contains a blank form that can be used to summarize the results. An example is shown in Figure 8-1. Copies ofthis form can be made by printing out file SUMMARY.



### 8-2RUN SYNOPSIS

Run Numbe r : File N :

A. CABINET
Reference Cabinet Design (Code Exceptions to Re ference Desi :

R. Refrigeration Cycle Reference Cycle Design (Code Number): Exceptions to Reference Design: Date:

C. S umma ry Results Reference Analysis Total Cabinet Load (w) Compressor Energy (kWh) Total Energy Use (kWh)

D. Findings and Conclusions:

Figure 8 -1. Summary Output Form RUN SYNOPSIS
Run Number:

____________ _ File Name:

A. CABINET Reference Cabinet Design (Code Number) : Exceptions to Reference Design:

B. Refrigeration Cycle Reference Cycle Design (Code Number) : Exceptions to Reference Design:

C. Summary Results Total Cabinet Load (w) Compressor Energy (kWh) Total Energy Use (kWh)

D. Findings and Conclusions: Reference

Figure 8-1. Summary Output Form.

8-3 Date:

__________ _

Analysis9.0 REFERENCES

1. "Engineering Computer Models for Refrigerators, Freezers, Furnaces, Water Heaters, Room and Central Air Conditioners," Report to U.S. DOE, by Arthur D. Little, Inc., November 1982. 2. McLinden, M., "Theoretical Vapor Compression Cycle, CYCLE7," unpublished. 3. Morrison, G., and McLinden, M., "Application of a Hard Sphere Equation of State to Refrigerants and Refrigerant Mixtures," National Bureau of Standards Technical 1 2 18,1986. 4. "NIST Standard Reference Database 23: NIST Thermodynamic Properties of Refrigerants and Refrigerant Mixtures Database, Version 3.0," NIST, December 1991. 5. "Multiple Pathways to Super Efficient Refrigerators," U.S. EPA, Global Change Division, Office of Atmospheric Programs, 1993. 6. Janssen, M.J.P., de Wit, J.A., and Kuijpers, L.J.M., "Cycling Losses in Domestic Appliances: An Experimental and Theoretical Analysis," Proceedings of the 1990USNC/IIR-Purdue Refrigeration Conference, July 17-20, 1990, Purdue University, West Lafayette, Indiana7. Alissi, H.S., Ramadhyani, S., and Schoenhals, R.J., "Effects of Ambient Temperature, Ambient Humidity, and Door Openings on Energy Consumption of a Household Refrigerator-Freezer," ASHRAE Transactions, 1988,94 (Part 2), pp. 

### 1713-1736. 9.0 REFERENCES 

### 1. "Engineering ComputerModels for Refrigerators, Freezers, Furnaces, WaterHeaters, Room and Central Air Conditioners," Report to U.S. DOE, by ArthurD. Little, Inc., November 1982. 2. McLinden, M., "Theoretical Vapor Compression Cycle, CYCLE7," unpublished. 3. Morrison, G., and McLinden, M., "Application ofa Hard Sphere Equation ofState to Refrigerants and Refrigerant Mixtures," National Bureau of Standards Technical Note 1218, 1986. 4. "NIST Standard Reference Database 23: NIST Thermodynamic Properties of Refrigerants and Refrigerant Mixtures Database, Version 3.0," NIST, December 1991. 

### 5. "Multiple Pathways to SuperEfficient Refrigerators," U.S. EPA, Global Change Division, Office ofAtmospheric Programs, 1993. 6. Janssen, M.J.P., de Wit, J.A., and Kuijpers, L.J.M., "CyclingLosses in Domestic Appliances: An Experimental and Theoretical Analysis,"**Proceedin~s** 

### ofthe 1990 USNCIIIR-Purdue Refrigeration Conference, July 17-20, 1990, Purdue University, West Lafayette, Indiana 7. Alissi, H.S., Ramadhyani, 

### S., and Schoenhals, R.J., "Effects ofAmbient Temperature, Ambient Humidity, and Door Openings on Energy Consumption ofa Household Refrigerator-Freezer," ASHRAE Transactions, 1988,.21 (Part 2), pp. 1713-1736.

9-1APPENDIX

OVERVIEW OF C ,®® T LOADS ANALYSIS TECHNICAL APPROACH

A.1 Wall Heat Loads A-2 A.2 Advanced Insulation Panels 

### A-3 A.3 Door Openings 

### A-6 A.4 Gasket Model 

### A-8 A.5 Anti-sweat Heat 

### A-8
A.6 References A-9 APPENDIX A OVERVIEW OF CABINET LOADS ANALYSIS TECHNICAL APPROACH

A.1 Wall Heat Loads A-2 A.2 Advanced Insulation Panels A-3 A.3 DoorOpenings A-6 AA Gasket Model A-8 A.5 Anti-sweat Heat A-8 A.6 References A-9

A-IA.1 Wall Heat LoadsThe major heat load on the cabinet results from heat conduction across the walls comprising the cabinet, with convection boundary conditions. Calculation of the conduction heat flow is based on the following assumptions: ® steady heat flow, with fixed thermal properties characterizing each wall; ® constant heat transfer coefficients; ® fixed inside and outside temperatures; ® one dimensional heat transfer (longitudinal heat flow is neglected). Corrections to the simple 1-D heat flow analyses are made for: ® comer and edge effects (to account for different outside and inside surface areas); ® composite structures, such as foam and vacuum panel sandwich constructions. The overall heat flow across a wall of the cabinet can be written:

Qw= (UA)w(T r -T) (A-1)
where U = overall heat transfer conductance

A = wall area (inside surface) 

### Tr = room temperature
T,, = cabinet temperature
The expression UA is composed of inside and outside film coefficients and areas, cabinet insulation properties, and correction factors for comers and edges:

UA = 1 (A -2) 1/h0Ao + 11UwA; + 1/h;A;
where hi, ho = film coefficients, inside and outside surfaces

Ai, A, = surface areas, inside and outside cabinet A.1 Wall Heat Loads The major heat load on the cabinet results from heat conduction across the walls comprising the cabinet, with convection boundary conditions. Calculation ofthe conduction heat flow is based on the following assumptions:

G steady heat flow, with fixed thermal properties characterizing each wall;

e constant heat transfer coefficients;

G fixed inside and outside temperatures; " one dimensional heat transfer (longitudinal heat flow is neglected). Corrections to the simple 1-D heat flow analyses are made for:

• comer and edge effects (to account for different outside and inside surface areas);

e composite structures, such as foam and vacuum panel sandwich constructions. The overall heat flow across a wall ofthe cabinet can be written: (A -1)
where U = overall heat transfer conductance A = wall area (inside surface) T 

# =room temperature

r T = cabinet temperature

c The expression UA is composed ofinside and outside film coefficients and areas, cabinet insulation properties, and correction factors for comers andedges: (A -2)

where 

### h h = film coefficients, inside and outside surfaces I' 0 A A = surface areas, inside and outside cabinet

I' 0

A-2= wall conductance w The wall conductance is the sum of the conductance across a plane, with corrections for the additional heat flow along the edges and at the comers [1]:



### U A,= kA,/

x+0.54kY,1;+0.l4nkt (A-3)

where 

### x = thickness of wall (ft)

k = thermal conductivity (Btu/hr-ft-F) I = inside edge length (ft) t = average insulation thickness (ft) n = number of corners Equation (A-3) gives the wall conduction in English units (Btu/hr-ft2-°F); the edge and comer correction factors assume the same units since this is the form in which they were first published [2]. Equations (A-1) through (A-3) are applied to all surfaces, including the mullion between the freezer and fresh food section, and the doors. Note that some average thermal conductivity, k, is assumed for the wall. Determination of the appropriate average value for an advanced insulation panel is discussed later. The values assumed for the inside and outside free convective surface heat transfer coefficients (including radiative heat transfer effects) are [1]:



### h; = 1.00 Btu/hr-ft2-°F (5.68 W/m2-C)
h,, = 1.47 Btu/hr-ft2-°F (8.35 W/m2-C)
A.2 Advanced Insulation PanelsThe use of advanced insulation panels may require installation of some sort of a sandwich of foam, and vacuum insulation panel. Depending on the thickness and material properties of the enclosing material, some "edge" effects for multidimensional heat transfer in the wall must be taken into account. The approach adopted by ERA is to determine approximate correction factors to the one dimensional heat flow. These factors are intended to account for: 1) heat flow along a conducting enclosure material, and 2) incomplete coverage of the wall by the high-R panel. Calculation of these factors is carried out in one of the Help menus in the input processor program. 

# u = 

### wall conductance

w 

### The wall conductance is the sum ofthe conductance across a plane, with corrections for the additional heat flow along the edges and at the corners [1]:

where


### x = 

### thickness ofwall (ft) 

### k 

### = thermal conductivity (Btu/hr-ft-F) I = 

### inside edge length (ft)
t 

### = average insulation thickness (ft)



### n = 

### number ofcorners (A -3)



### Equation (A-3) gives the wall conduction in English units (Btu/hr-fr-T); the edge and cornercorrection factors assume the same units since this is the form in which they were first published [2]. 

### Equations (A-I) through (A-3) are applied to all surfaces, including the mullion between the freezer and fresh food section, and the doors. Note that some average thermal conductivity,

## k, is assumed for the wall. Determination ofthe appropriate average value for an advanced insulation panel is discussed later. The values assumed for the inside and outside free convective surface heat transfer coefficients (including radiative heat transfer effects) are [1]; 

### h = 

### 1.00 Btu!hr-fe-T (5.68 W/m2-C)

I 

### h 

### = 1.47 Btu/hr-ff-T (8.35 W/m2-C)

o A.2 Advanced Insulation Panels 

### The use ofadvanced insulation panels may require installation ofsome sort ofa sandwich offoam, and vacuum insulation panel. Depending on the thickness and material properties ofthe enclosing material, some "edge" effects for multidimensional heat transfer in the wall must be taken into account. The approach adopted by ERA is to determine approximate correction factors to the one dimensional heat flow. These factors are intended to account for: 1) heat flow along a conducting enclosure material, and 2) 

### incompletecoverage ofthe wall by the high-R panel. Calculation ofthese factors is carried out in one ofthe Help menus in the input processor program.
A-3Figure A-1 illustrates the general geometrical situation treated by the model. Parameters describing the configuration are: the overall dimensions of the wall slab, the distances from the edges of the high resistance center panel to each of the four edges of the slab (they may be different), the distances from the two faces of the panel to the inside and outside surfaces of the wall (one or both may be zero), the panel resistivity in the absence of edge losses, the panel enclosure thickness, and the enclosure thermal conductivity. Note that wall slabs may have one or more beveled edges, depending on the cabinet element under consideration. As noted in Figure A-1, the refrigerator wall is treated as a composite system of foam and an interior high-resistance panel. Foam along the side of the panel contributes tothe net "heat transfer coefficient" on the side by combining with the air-side film coefficient; the inverse of the net resistance is the effective heat transfer coefficient along the panel side. Heat transfer through the foam along the edges is considered parallel heat transfer; that is, the wall is broken into two sections, one containing the panel, and the other containing pure foam. Although the method ignores the possibilities of "shortcircuiting" of heat through the foam around the panel, detailed finite difference calculations for practical geometries and panel properties showed this to be a very small effect. However, as discussed in the next paragraph, short circuiting of heat along the a high conductivity panel enclosure was taken into account. As a first step in the calculation of the overall thermal resistance, the perimeter heat loss from a semi-infinite slab containing the thermally conducting panel enclosure is established. A standard fin analysis is utilized to represent the longitudinal heat flows along the enclosure surfaces towards the edges (perimeter). The calculated perimeter heat flow is considered as a parallel heat flow term to the normal heat flow across the semi-infinite slab. Calculations for perimeter heat flow are carried out independently for both directions: a semi-infinite slab in the width direction and a semi-infinite slab in the length direction. Because of comer effects, the two perimeter heat flows are not additive. They are combined using a correction factor, based on the relative dimensions of the panel edges in the width and length directions. Once the total perimeter heat flow is established the net resistance of the wall slab is determined. Although the approach is only approximate, it is intended to capture most of the effects associated with multidimensional heat transfer with composites of foam and vacuum insulation panels. This has been confirmed by comparing ERA model predictions with the results of a high resolution finite element analysis, performed on a main frame computer, of several test conditions. Two generic cases were considered: 1) a composite flat square slab of 36 inch by 36 inch, 1.5 inch thick, with 0.5 inch thick vacuum panel in the center, and with 0.5 inch foam on either side; 2) a corner of a two foot cube with 1.5 inch thick walls and with a vacuum panel located in the center of the wall. Case 1 is typical of a the geometry of a door element. Case 2 is typical of the back wall of a cabinet (where the outside surfaceis larger than the inside surface). The inner panel consists of an evacuated r-20 powder enclosed in an 8-mil stainless steel structure. The results of these two test cases are summarized below:
A-4 

### Figure A-I illustrates the general geometrical situation treated by the model. Parameters describing the configuration are: the overall dimensions ofthe wall slab, the distances from the edges ofthe high resistance center panel to each ofthe four edges of the slab (they may be different), the distances from the two faces ofthe panel to the inside and outside surfaces ofthe wall (one orboth may be zero), the panel resistivity in the absence ofedge losses, the panel enclosure thickness, and the enclosure thermal conductivity. Note that wall slabs may have one or more beveled edges, depending on the cabinet element under consideration. As noted in Figure A-I, the refrigerator wall is treated as a composite system offoam and an interior high-resistance panel. Foam along the side ofthe panel contributes to the net "heat transfer coefficient" on the side by combining with the air-side film coefficient; the inverse ofthe net resistance is the effective heat transfer coefficient along the panel side. Heat transfer through the foam along the edges is considered parallel heat transfer; that is, the wall is broken into two sections, one containing the panel, and the other containing pure foam. Although the method ignores the possibilities of "short circuiting" ofheat through the foam around the panel, detailed finite difference calculations for practical geometries and panel properties showed this to be a very small effect. However, as discussed in the next paragraph, short circuiting ofheat along the a high conductivity panel enclosure was 

### taken into account. As a first step in the calculation ofthe overall thermal resistance, the perimeter heat loss from a semi-infinite slab containing the thermally conducting panel enclosure is established. A standard fin analysis is utilized to represent the longitudinal heat flows along the enclosure surfaces towards the edges (perimeter). The calculated perimeter heat flow is considered as a parallel heat flow term to the normal heat flow across the semi-infinite slab. Calculations for perimeter heat flow are carried out independently for both directions: a semi-infinite slab in the width direction and a semi-infinite slab in the length direction. Because ofcomer effects, the two perimeter heat flows are not additive. They are combined using a correction factor, based on the relative dimensions ofthe panel edges in the width and length directions. Once the total perimeter heat flow is established the net resistance ofthe wall slab is determined. Although the approach is only approximate, it is intended to capture most ofthe effects associated with multidimensional heat transfer with composites offoam and vacuum insulation panels. This has been confrrmed by comparing ERA model predictions with the results ofa high resolution finite element analysis, performed on a main frame computer, of several test conditions. Two generic cases were considered: 1) a composite flat square slab of36 inch by 36 inch, 1.5 inch thick, with 0.5 inch thick vacuum panel in the center, and with 0.5 inch foam on either side; 2) a comer ofa two foot cube with 1.5 inch thick walls and with a vacuum panel located in the center ofthe wall. Case 1 is typical ofa the geometry ofa door element. Case 2 is typical ofthe back wall ofa cabinet (where the outside surface is larger than the inside surface). The inner panel consists ofan evacuated r-20 powder enclosed in an 8-mil stainless steel structure. The results ofthese two test cases are summarized below:
A-4

## w



# Figure A

-

# 1. Ad van 

# ned Insulation Composite System Foam

L



# I
... 

# w

Figure 

# A ..1.. Foam 

# &Advanced Insulation Composite SystemDistance of Panel from an Edge (in) Overall Resistance (Finite Element) Overall Resistance (E RA Model) Case 1 0 14.34 14.58



### 1 13.69 13.90 6 11.61 

### 11.68 12 10.54 

### 10.57
Case 2 +1 15.66 16.05

+0.5 15.51 15.22 0 15.16 14.50 -1 14.23 13.31 -2 12.96 12.39 all foam 9.32 9.31 The maximum difference between the very detailed (and time consuming) finite element solution and the ERA simplified algorithm solutions for these two test cases is about 6%, with an average difference of about 2%. Hence, for the purposes of the types of design tradeoffs to be carried out with ERA, the model appears adequate. A.3 Door OpeningsA simplified model for the effects of open doors on the cabinet loads has been developed. A basis for the model is provided by the published work of Alissi, et. al. [3]. Door openings introduce dynamic phenomena into the net heat exchange between the cabinet and the room air. At least four flow patterns are set up during the period thedoor is open: 1) cool air will drain from the bottom of the cabinet due to density gradient driving forces, 2) warm air is sucked into the cabinet as the door is opened due to the pressure gradient caused by the opening, 3) natural convection will occur between the warm and cool air due to the buoyancy force differences, and 4) the cabinet air will be disturbed due to human factors.Modeled heat and mass transfer between the cabinet and the room air assumes two distinct phenomena: 1) an initial tumbling of the air (essentially immediate replacement of the air occurs), 2) long term continuous convective flow and mass exchange. Modeledconvective sensible heat flow rates are dependent on the room air to cabinet wall temperature difference. The air densities and partial pressures of water vapor in the compartment and room determine the rate of mass (water vapor) exchange.All moisture that enters the cabinet is assumed to condense, releasing a heat of condensation. In addition, moisture that enters the freezer compartment, either directly or through air exchange with the fresh food compartment, is assumed to form frost. This releases an additional amount of heat in the freezer compartment. If the appliance uses



### A-6 Distance of Panel OverallResistance OverallResistance from an Edge (in) (Finite Element) (ERA Model) Case 1 0 14.34 14.58 1 13.69 13.90 6 11.61 11.68 12 10.54 10.57
Case 2 +1 15.66 16.05 +0.5 15.51 15.22

0 15.16 14.50 -1 14.23 13.31 -2 12.96 12.39 all foam 9.32 9.31 The maximum difference between the very detailed (and time consuming) fmite element solution and the ERA simplified algorithm solutions for these two test cases is about 6%, with an average difference ofabout 2%. Hence, for the purposes ofthe types ofdesign tradeoffs to be carried out with ERA, the model appears adequate. 

### A.3 Door Openings A simplified model for the effects ofopen doors on the cabinet loads has been developed. A basis for the model is provided by the published work ofAlissi, et. al. [3]. Dooropenings introduce dynamic phenomenainto the net heat exchange between the cabinet and the room air. At least four flow patterns are set up during the period the door is open: 1) cool air will drain from the bottom ofthe cabinet due to density gradient driving forces, 2) warm air is sucked into the cabinet as the door is opened due to the pressure gradient caused by the opening, 3) natural convection will occur between the warm and cool air due to the buoyancy force differences, and4) the cabinet air will be disturbed due to human factors. Modeled heat and mass transfer between the cabinet and the room air assumes two distinct phenomena: 1) an initial tumbling ofthe air (essentially immediate replacement of the air occurs), 2) long term continuous convective flow and mass exchange. Modeled convective sensible heat flow rates are dependent on the room air to cabinet wall temperature difference. The air densities andpartial pressures ofwater vapor in the compartment and room determine the rate ofmass (water vapor) exchange. All moisture that enters the cabinet is assumed to condense, releasing a heat ofcondensation. In addition, moisture that enters the freezer compartment, either directly or through air exchange with the fresh food compartment, is assumed to form frost. This releases an additional amount ofheat in the freezer compartment. Ifthe appliance uses

A-6automatic defrost, the heat required to melt the frost will be a further heat load on the

freezer; if manual defrost is assumed, the heat of defrost is not part of the overall heat load. As discussed, the net heat load due to each door opening is comprised of four terms: ® Initial Sensible Load: 

### Q,= PC,(7',- T)(Vn) (A -4)
® Initial Latent Load 

## Q, = (0)Q -W C)hfg(Vcn) 

### (A-5)

® Convective Sensible Load Q h[Al(°,-T )bd 

### (A -6)
® Convective Latent Load Q ,j 

### = hm(hig) (Op, 

### - P)AItd (A -7)
where Ai = inside surface area of cabinet


### h = convective heat transfer coefficient hig = heat of sublimation
hfg = heat ofcondensation
hm = mass transfer coefficient (related to convective heat transfer coefficient) T,; = cabinet air temperature
Tr = room temperature

td = length of time the door is open each hour

Vin = volume of cabinet times number of times door opened during the hour automatic defrost, the heat required to melt the frost will be a further heat load on the freezer; ifmanual defrost is assumed, the heat ofdefrost is not part ofthe overall heat load. As discussed, the net heat load due to each door opening is comprised offour terms:

• Initial Sensible Load: (A -4)
" Initial LatentLoad (A -5)
" Convective Sensible Load (A -6)

.. Convective Latent Load (A -7)
where 

### A. = inside surface area ofcabinet I 

### h 

### = convective heat transfer coefficient h. = heat ofsublimation

Ig 

### h fg = heat ofcondensation


### h = mass transfer coefficient (related to

m convective heat transfer coefficient) 

### Tc 

### = cabinet air temperature


### Tr = room temperature

td = length oftime the dooris open each hour

V

### n = volume ofcabinet times number oftimes

c door opened during the hour

A-7and 0 = relative humidity p^ = density of air at cabinet temperature
Pr = density of air at room temperature
= humidity ratio of room air (r) or cabinet air (c) The above equations hold for all cabinet types except the chest freezer. Here, it is assumed that there is not an initial emptying of the cabinet, and that the heat and mass transfer coefficients are one half of those for an upright unit. AA Gasket Model The gasket model assumes that the rate of heat input is a linear function of the gasket path length (door perimeter) and the room-cabinet temperature difference. In actuality, the rate of heat leak may be influenced by fan operation, and may vary according to the tightness of fit. A detailed finite element analysis carried out the by University of Kentucky [4] has shown that the major paths for heat flow are along the cabinet flange and the door flange, with a lesser amount through the gasket itself. Because of the complexity of the heat flows in this region, ERA relies on the user to specify realistic values for the heatloss coefficient, rather than attempting to model the gasket region itself. Typical values for heat loss are provided in the Help menu. A.5 Anti-sweat Heat. Anti-sweat heat may be applied along the front surface of the cabinet and across the front face of the mullion. It may be supplied from electrical resistance heater wires,hot gas leaving the compressor prior to entering the condenser or heat from the refrigerant leaving the condenser. If electric heater wires are used, standard closed door rating tests normally require that the refrigerator performance be measured with the heaters on and then with the heaters off. The rating is based on the average of these tests. As a short cut analyticalapproach, the user may assume that the DOE test conditions are equivalent to measuring performance with half the anti-sweat heat input. Operation of the heaters is continuous, not dependent on the behavior of the refrigeration system. and

<1> = relative humidity 

### Pc = density ofair at cabinet temperature


### Pr = density ofair at room temperature



### ro

## = humidity ratio ofroom air (r) orcabinet air (c) The above equations hold for all cabinet types except the chest freezer. Here, 

### it is assumed that there is not an initial emptying ofthe cabinet, and that the heat and mass transfer coefficients are one halfofthose for an upright unit. A.4 Gasket Model The gasket model assumes that the rate ofheat input is a linear function ofthe gasket path length (door perimeter) and the room-cabinet temperature difference. In actuality, the rate ofheat leak may be influenced by fan operation, and may vary according to the tightness offit. A detailed finite element analysis carried out the by University ofKentucky [4] has shown that the major paths for heat flow are along the cabinet flange and the door flange, with a lesser amount through the gasket itself. Because ofthe complexity ofthe heat flows in this region, ERA relies on the user to specify realistic values for the heat loss coefficient, rather than attempting to model the gasket region itself. Typical values for heat loss are provided in the Help menu. A.5 Anti-sweat Heat. Anti-sweat heat may be applied along the front surface ofthe cabinet and across the front face ofthe mullion. Itmay be supplied from electrical resistance heater wires, hot gas leaving the compressorprior to entering the condenserorheat from the refrigerant leaving the condenser. Ifelectric heater wires are used, standard closed doorrating tests normally require that the refrigeratorperformance be measured with the heaters on and then with the heaters off. The rating is based on the average ofthese tests. As a short cut analytical approach, the user may assume that the DOE test conditions are equivalent to measuring performance with halfthe anti-sweat heat input. Operation ofthe heaters is continuous, not dependent on the behavior ofthe refrigeration system.

A-8If hot gas from the compressor output line, or heat from the condenser liquid line, is

used for door flange and/or mullion heating, the net heat input will be dependent upon the compressor run time. This is modelled by specifying the value for refrigerant line anti-sweat heat input equal to that used for switchable electric heat in the on-position. For example, if a 6 watt electric heater (average of 3 watts in simulation of the DOEtest condition) is replaced by liquid line heat, the user should specify 6 watts of refrigerant line heat. Since refrigerant line heat is not "switchable" the total heat input will be larger than the average heat input corresponding to the DOE test conditions. ERA will calculate the on-cycle heat removal required from the refrigerant line heater to supply the cycle-averaged specified heat input. For example, if a cycle-average heat input of 6 watts is specified and the duty cycle is 45%, the on-cycle heat removal must be 6/0.45 = 13.3 watts. If this would result in an overcooling of the refrigerant line, ERA will issue a warning message in the summary output (ERA.OUT). Then the user must reduce the specified refrigerant line heat and replace the amount reduced with switchable electric heat. Hence, is some situations the mullion may receive anti-sweat from a liquid line and from a (smaller) electric heater at the same time. 

### AX References1. "Engineering Computer Models for Refrigerators, Freezers, Furnaces, water Heaters, Room and Central Air Conditioners," Report to U.S. DOE by Arthur D. Little, Inc, November, 1982. 

### 2. Langmuir, I., Adams, E., And Meikle, G., "Flow of Heat Through Furnace Walls: The Shape Factor," Trans. Amer. Electrochem. Soc., 24, pp. 53-84 (1913).3. Alissi, M.S., Ramadhyani, S., and Schoenhals, R.3., "Effects of Ambient Temperature, Ambient Humidity, and Door Openings on Energy Consumption of a Household Refrigerator-Freezer," ASHRAE Transactions, 1988,94 (Part 2), pp. 1713 - 1736.4. "Finite Element Analysis of Heat Transfer Through the Gasket Region of Refrigerator/Freezers," EPA/430/R-92/009. Ifhot gas from the compressor output line, orheat from the condenser liquid line, is used for door flange and/or mullion heating, the net heat input will be dependent upon the compressorrun time. This is modelled by specifying the value for refrigerant line anti-sweat heat input equal to that used for switchable electric heat in the on-position. Forexample, ifa 

### 6 watt electric heater (average of

### 3 watts in simulation ofthe DOE test condition) is replaced by liquid line heat, the user should specify 

### 6 watts ofrefrigerant line heat. Sincerefrigerant line heatis not "switchable" the total heat input will be larger than the average heat input corresponding to the DOE test conditions. ERA will calculate the on-cycle heat removal required from the refrigerant line heater to supply the cycle-averaged specified heat input. Forexample, ifa cycle-average heat input of6 watts is specified and the duty cycle is 45%, the on-cycle heatremoval must be 6/0.45 

# =13.3 watts. Ifthis wouldresult in an overcooling ofthe refrigerant line, ERA will issue a warning message in the summary output (ERA.OUT). Then the user must reduce the specifiedrefrigerant line heat andreplace the amountreduced with switchable electric heat. Hence, is some situations the mullion may receive anti-sweat from a liquid line and from a (smaller) electric heater at the same time. 

### A.S References 1. "Engineering ComputerModels for Refrigerators, Freezers, Furnaces, water Heaters, Room and Central Air Conditioners," Report to U.S. DOE by ArthurD. Little, Inc, November, 1982. 2. Langmuir, I., Adams, E., And Meikle, G., "Flow ofHeat Through Furnace Walls: The Shape Factor," Trans. Amer. Electrochem. Soc., 24, pp. 53-84 (1913). 3. Alissi, M.S., Ramadhyani, S., and Schoenhals, R.J., "Effects ofAmbient Temperature, Ambient Humidity, and DoorOpenings on Energy Consumption ofa Household Refrigerator-Freezer," ASHRAE Transactions, 1988,**~** (Part 2), pp. 1713

- 1736. 4. "Finite Element Analysis ofHeatTransfer Through the Gasket Region ofRefrigerator/Freezers," EPN430/R-92/009.

A-9APPENDIX OVERVIEW OF CYCLE ANALYSIS TECHNICAL APPROACH

B.1 Cycle Model Solution Procedure B-2 B.2 Compressor Performance Models B-5 B2.1 Physically Based Compressor Model B-5 B2.2 Rating Point Compressor Model B-10 B2.3 Map Based Compressor Model B-13 B.3 Cycling Losses B-15 B3.1 Cycling Rates B-16 B.3.2 Cycling Losses Without a Valve B-16 B.3.3 Cycling Effects with a Shut-off Valve B-16 B.4 Summary of Help Menu Heat Exchanger Analyses B-17 B.4.1 Air-Side Heat Transfer Coefficients B-18 B.4.2 Refrigerant-Side Heat Transfer Coefficients and Pressure Drops B- 19
B.4.3 Fluid Properties B-20 B.5 Corrections for Hot-Wall Condenser or Cold-Wall Evaporator B-20 B.6 Matching Evaporator Capacities and Cabinet Loads B-22 B.6.1 Single Evaporator Cycle B-22 B.6.2 Dual Loop B-23 B.6.3 Dual Evaporator Cycle B-23 B.7 Variable Speed Operation B-23 B.8 References B-24 APPENDIX B OVERVIEW OF CYCLE ANALYSIS TECHNICAL APPROACH

B.1 Cycle Model Solution Procedure B-2 B.2 Compressor Perfonnance Models B-5 B2.1 Physically Based Compressor Model B-5 B2.2 Rating Point Compressor Model B-lO B2.3 Map Based Compressor Model B-13 B.3 Cycling Losses B-15 B3.1 Cycling Rates B-16 B.3.2 Cycling Losses Without a Valve B-16 B.3.3 Cycling Effects with a Shut-offValve B-16 

### BA Summary ofHelp Menu Heat ExchangerAnalyses B-17 B.4.1 Air-Side Heat Transfer Coefficients B-18 

### BA.2 Refrigerant-Side Heat Transfer Coefficients and B-19 Pressure Drops 

### BA.3 FluidProperties B-20 B.5 Corrections for Hot-Wall Condenseror Cold-WallEvaporator B-20 B.6 Matching Evaporator Capacities and Cabinet Loads B-22 B.6.1 Single Evaporator Cycle B-22 B.6.2 Dual Loop B-23 B.6.3 Dual Evaporator Cycle B-23 B.7 Variable Speed Operation B-23 B.8 References B-24

B-1B.1 Cycle Model Solution Procedure E CYC.E is an iterative solver that starts with initial guesses for the refrigerantmass flow rate and the refrigerant temperatures at the exits of the condenser and evaporator. A converged solution is reached when a global energy balance for the entire refrigeration system is satisfied while satisfying local energy balances and heat transferrelationships for each system component. Schematic diagrams of a two evaporator system and single evaporator system, along with refrigerant state points are shown in Figures B-i and B-2. The refrigerant state points are defined in Table B-1.

Table B-1. Summary of Refrigerant State Point Locations

compressor inlet compressor outlet condenser inlet refrigerant dew point within condenser refrigerant bubble point within condenser condenser exit inlet to high temperature interchanger outlet from high temperature interchanger (also the inlet to the low temperature interchanges) 9* outlet from the low temperature interchanger 10 freezer evaporator inlet 11" freezer evaporator outlet

(also the inlet to the low temperature interchanger) 12" fresh food evaporator inlet

(also the outlet from the low temperature interchanger) 13 refrigerant dew point within fresh food evaporator 14 fresh food evaporator outlet

(also the inlet to the high temperature evaporator) 15 outlet from the high temperature evaporator - This state point is set equal to state (8) when a single evaporator cycle is specified. "° - These state points are set equal to state (10) when a single evaporator cycle is specified. For calculation purposes, the program divides the refrigeration cycle into the following two major subsystems: 1. a high-pressure subsystem that includes the compressor, condenser, and refrigerant lines, including state (1) up through and including state (7) on Figure B-1, and 2. a low-pressure subsystem that includes the high and low temperature interchangers, expansion device, freezer and fresh food evaporators, and refrigerant lines starting after state (7) up through and including state (15). B.1 Cycle Model Solution Procedure ERACYC.EXE is an iterative solver that starts with initial guesses for the refrigerant mass flow rate and the refrigerant temperatures at the exits ofthe condenser and evaporator. A converged solution is reached when a global energy balance for the entire refrigeration system is satisfied while satisfying local energy balances and heat transfer relationships for each system component Schematic diagrams ofa two evaporator system and single evaporator system, along with refrigerant state points are shown in Figures B-1 and B-2. The refrigerant statepoints are defined in Table B-l.

Table B-1. Summary of Refrigerant State Point Locations

compressor 2 compressor outlet 3 condenser inlet 4 refrigerant dew point within condenser 5 refrigerant bubble point within condenser 6 condenser exit 7 inlet to high temperature interchanger 8 outlet from high temperature interchanger (also the inlet to the low temperature interchanger) 9' outlet from the low temperature interchanger 10 freezer evaporator inlet 11" freezer evaporator outlet (also the inlet to the low temperature interchanger) 12" fresh food evaporator inlet (also the outlet from the low temperature interchanger) 13 refrigerant dew point within fresh food evaporator 14 fresh food evaporator outlet (also the inlet to the high temperature evaporator) 15 outlet from the high temperature evaporator " - This state point is set equal to state (8) when a single evaporator cycle is specified. **
- These state points are set equal to state (10) when a single evaporator cycle is specified.
For calculation purposes, the programdivides the refrigeration cycle into the following two major subsystems: 1. a high-pressure subsystem that includes the compressor, condenser, and refrigerant lines, including state (1) up through and including state (7) on Figure B-1, and 

### 2, a low-pressure subsystem that includes the high and low temperature interchangers, expansion device, freezer and fresh food evaporators, and refrigerant lines starting after state (7) up through and including state (15).

B-25 condenser

compressor

high t p Interchan r

low temp I nterchanger
expansion device 0 15

12

10 re "r! :- it flow

fresh food evaporator 13 14

freezer evaporator 11 Figure S

-1. Schematic Diagram of a Two Evaporator Cycle and Corresponding Refrigerant State Points 5 4 

### t- condenser --f 3



### compressor

interchan er

expansion device 7



### 0

# 0 L 15



### evaporator -I 13 refrigerant flow

Figure B

-2. Schematic Diagram of a Single Evaporator Cycle and Corresponding Refrigerant State Points Figure 8-1. Schematic Diagram of a Two Evaporator Cycle and Corresponding Refrigerant State Points

interchanger

expansion device 5 4 6 ,--------, 3 .-----+-+--+- condenser -+-+-+--
.... --.

compressor



### 7 15

r-+-+-, refrigerant flow



### 8

L-----t-t--- evaporator -+--+-+-_.-J**12~----------~14** 

### 13 Figure 8-2. Schematic Diagram of a Single Evaporator Cycle and Corresponding Refrigerant State Points



### B-3The low-pressure subsystem is broken further into the following two components: a. a fresh food component that includes the high temperature interchanger and fresh food evaporator, from (but not including) state (7) and including states (8), (12), (13), (14), and (15). b. a freezer evaporator component that includes the low temperature interchanger, expansion device, freezer evaporator, from (but not including) state (8) and including states (9), (10), and (11), and up to, but not including state (12). An outline of the general solution algorithm is as follows: 1. The program guesses initial values for the refrigerant mass flow rate, condenser exittemperature, fresh food evaporator exit temperature, and freezer evaporator temperature, which correspond to states (6), (14), and (11) on Figure B-1. 2. Based on the user specified values for liquid subcooling at the condenser exit and vapor superheating at the evaporator exit, the program calculates the liquid bubble point at state (5) and the vapor dew point at state ( 13). Based on these temperatures, the remainder of the refrigerant properties, (i.e., saturation pressures , enthalpies, specific volumes, etc.) are calculated. The program then calculates the remainder of the refrigerant properties at states (6) and (14).3. Holding the refrigerant mass flow rate and properties at state (7) constant, the program iterates to solve an energy balance and the heat transfer relationships for the low pressure side of the system, as described in the following: a. Based on the refrigerant properties at states (7) and (14), state (8) at the high temperature is determined. b. Using state (8) as the inlet to the low temperature interchanger, the program iterates to solve for states (9), (10), (11), and (12) and the freezer evaporator performance. The freezer evaporator performance is determined using the heatexchanger relationships for the evaporator along with refrigerant-side and airside energy balances

. Convergence is achieved when the difference between the values of the refrigerant temperature at the freezer evaporator exit for two successive iterations is less than a user defined value (see file CYCLE.TOL). If a single evaporator system is specified , the program internally sets refrigerant state (9) equal to state (8), and (11 ) and (12) equal to state ( 10). A single evaporator system is shown schematically in Figure B-2. c. Using state ( 12) as the inlet state to the fresh food evaporator , the program solves for the heat transfer in the fresh food evaporator based on heat exchanger relationships for the evaporator along with refrigerant

-side and airside energy balances. The low-pressure subsystem is broken further into the following two components:

a. a fresh food component that includes the high temperature interchanger and fresh food evaporator, from (but not including) state (7) and including states (8), (12), (13), (14), and (15). b. a freezer evaporator component that includes the low temperature interchanger, expansion device, freezer evaporator, from (but not including) state (8) and including states (9), (10), and (11), and up to, but not including state (12). An outline ofthe general solution algorithm is as follows: 1. The program guesses initial values for the refrigerant mass flow rate, condenser exit temperature, fresh food evaporator exit temperature, and freezer evaporator temperature, which correspond to states (6), (14), and (11) on Figure B-l. 2. Based on the user specified values for liquid subcooling at the condenser exit and vapor superheating at the evaporator exit, the program calculates the liquid bubble point at state (5) and the vapor dew point at state (13). Based on these temperatures, the remainder ofthe refrigerant properties, (Le., saturation pressures, enthalpies, specific volumes, etc.) are calculated. The program then calculates the remainder ofthe refrigerant properties at states (6) and (14). 3. Holding the refrigerant mass flow rate and properties at state (7) constant, the program iterates to solve an energy balance and the heat transferrelationships for the low pressure side ofthe system, as described in the following:

a. Based on the refrigerant properties at states (7) and (14), state (8) at the high temperature is determined. b. Using state (8) as the inlet to the low temperature interchanger, the program iterates to solve for states (9), (10), (11), and (12) and the freezer evaporator performance. The freezer evaporator performance is determined using the heat exchangerrelationships for the evaporator along withrefrigerant-side and airside energy balances. Convergence is achieved when the difference between the values ofthe refrigerant temperature atthe freezer evaporator exit for two successive iterations is less than a user defined value (see file CYCLE.TOL). Ifa single evaporator system is specified, the program internally sets refrigerant state (9) equal to state (8), and (11) and (12) equal to state (10). A single evaporator system is shown schematically inFigure B-2.

c. Using state (12) as the inlet state to the fresh food evaporator, the program solves for the heat transfer in the fresh food evaporatorbased on heat exchangerrelationships for the evaporator along with refrigerant-side and airside energy balances.

B-4d. The refrigerant enthalpy difference between states (14) and (12) are compared to the heat transfer calculated in Step 3c. Depending on the difference between these two quantities, the refrigerant exit temperature (state (14)) is adjusted to reduce this difference. e. Steps 3a through 3d are repeated until a converged solution is reached for the low pressure side of the system

. A converged solution on the low-pressure side of the system is achieved when the difference in the refrigerant evaporator exit temperatures for two successive iteration steps is less than a user defined value (see file CYCLE.TOL). 4. Based on states (7) and (14), the high temperature interchangerperformance is determined, along with state (15). 5. State (1) at the inlet to the compressor is determined.6. Compressor performance is determined using a theoretically based model, an efficiency/capacity based model, or a tabulated performance based model. Outputs from the compressor calculation include the compressor power requirement, compressor heat loss, the refrigerant properties at state (2), and a new value for the refrigerant mass flow rate. 7. The refrigerant properties at the condenser inlet, state (3), are calculated. 8. Next, the program solves for the heat transfer in the condenser, based on heat exchanger relationships for the condenser along with refrigerant-side and air-side energy balances. 9. The refrigerant enthalpy difference between states (6) and (3) are compared to the heat transfer calculated in Step S. Depending on the difference between these twoquantities, the refrigerant exit temperature at state (6) is adjusted to reduce this difference. 10. Based on the new values for the refrigerant mass flow rate and refrigerant properties at state (6), the program repeats Steps 2 through 9 until a converged solution for condenser exit temperature and refrigerant mass flow rate has been obtained. A converged solution on the high-pressure side of the system is achieved when the differences between the refrigerant condenser exit temperatures and the refrigerant mass flow rates for two successive iteration steps are less than user defined values (see file CYCLE.TOL).

8.2 Compressor Performance Models B.2.1. Physically Based Compressor Model (Efficiency Model) This section summarizes the basic structure of the physically based compressor model employed in the program module ERACYC. The analysis is a hybrid between a purely theoretical model and an empirical model in that it uses empirical coefficients as inputs d. Therefrigerant enthalpy difference between states (14) and (12) are compared to the heat transfer calculated in Step 3c. Depending on the difference between these two quantities, the refrigerant exit temperature (state (14» is adjusted to reduce this difference.

e. Steps 3a through 3d are repeated until a converged solution is reached for the low pressure side ofthe system. A converged solution on the low-pressure side ofthe system is achieved when the difference in the refrigerant evaporator exit temperatures for two successive iteration steps is less than a user defmed value (see file CYCLE.TOL). 4. Based on states (7) and (14), the high temperature interchangerperformance is determined, along with state (15). 5. State (1) at the inlet to the compressor is determined. 6. Compressorperformance is determined using a theoretically based model, an efficiency/capacity based model, or a tabulated performance based model. Outputs from the compressor calculation include the compressor powerrequirement, compressor heat loss, the refrigerant properties at state (2), and a new value for the refrigerant mass flow rate. 7. The refrigerant properties at the condenser inlet, state (3), are calculated. 8. Next, the program solves for the heat transfer in the condenser, based on heat exchanger relationships for the condenser along with refrigerant-side and air-side energy balances. 9. Therefrigerant enthalpy difference between states (6) and (3) are compared to the heat transfer calculated in Step 8. Depending on the difference between these two quantities, the refrigerant exit temperature at state (6) is adjusted to reduce this difference. 10. Based on the new values for the refrigerant mass flow rate and refrigerantproperties at state (6), the programrepeats Steps 2 through 9 until a converged solution for condenser exit temperature and refrigerant mass flow rate has been obtained. A converged solution on the high-pressure side ofthe system is achieved when the differences between the refrigerant condenser exittemperatures and the refrigerant mass flow rates for two successive iteration steps are less than user defined values (see file CYCLE.TOL).
13.2 Compressor Performance Models B.2.1. Physically Based Compressor Model (Efficiency Model) This section summarizes the basic structure ofthe physically based compressor model employed in the programmodule ERACYC. The analysis is a hybrid between a purely theoretical model and an empirical model in that it uses empirical coefficients as inputs



### B-5to theoretically derived equations

. A description is provided of the basic physical processes that are represented, the analysis assumptions, and the equation set developed to characterize the performance parameters. 

### Physical Processes Modeled The model is based on representing the following physical processes depicted in Figure B-3: ® The compressor is a low side hermetic reciprocating design.• Suction gas (state point 1 in Figure B-3) enters the shell and is in thermal communication with the discharge line and with the motor, providing its main cooling. ® The motor is entirely within the shell and is physically separated from it. ® The suction gas transfers heat to the shell which is in thermal communication with its environment. ® The suction gas enters the pump inlet valve in a heated condition (state point 2) and is compressed to a higher pressure. ® At the outlet of the pump (state point 3) the refrigerant gas enters a discharge line which is in thermal communication with the refrigerant vapor contained within the compressor shell volume. ® After losing heat to the gas within the shell, the high pressure discharge gas leaves the compressor (state point 4). ® No pressure changes are taken into account within the shell other than across the pump (point 2 to 3). The net pressure change includes pressure losses through the pump suction and discharge valves. Figure B-4 illustrates the thermodynamic state points of the gas throughout the modeled process. to theoretically derived equations. A description is provided ofthe basic physical processes that are represented, the analysis assumptions, and the equation set developed to characterize the performance parameters. Physical Processes Modeled The model is based on representing the following physical processes depicted in Figure B-3:

.. The compressor is a low side hermetic reciprocating design.

.. Suction gas (state point 1 in Figure B-3) enters the shell and is in thermal communication with the discharge line and with the motor, providing its main cooling. " The motor is entirely within the shell and is physically separated from it. " The suction gas transfers heat to the shell which is in thermal communication with its environment.

.. The suction gas enters the pump inlet valve in a heated condition (state point 2) and is compressed to a higher pressure.

.. Atthe outlet ofthe pump (state point 3) the refrigerant gas enters a discharge line which is in thermal communication with the refrigerantvapor contained within the compressor shell volume.

.. Mter losing heat to the gas within the shell, the high pressure discharge gas leaves the compressor (state point 4).

.. No pressure changes are taken into account within the shell other than across the pump (point 2 to 3). The netpressure change includes pressure losses through the pump suction and discharge valves. Figure B-4 illustrates the thermodynamic statepoints ofthe gas throughout the modeled process.



### B-6

## 2



## motor

w
Figure B®3. Physical Processes in Compressor



## p pressu re,

enthalpy, Figure B-4. Thermodynamic State Points in Compressor 

## 4

., 

# I 

# - 1 

## 2 3 "'" "'" 

# - - pump 

# J J motor**A~**


# w Figure B-3. Physical Processes in Compressor



## 4 3 

## pressure, p

2
enthalpy, h Figure B-4. Thermodynamic State Points in Compressor



### B-7

### The thermal processes represented are:® The shell heat transfer is correlated to motor inlet power. For the purposes of simplification, it is assumed that the constant of proportionality is independent of the actual operating conditions. Input values for the shell heat loss are based on actual compressor performance data and are typically 70 - 80 percent of the compressor inlet power. ® The internal heat exchange between the high pressure gas within the discharge line and the low pressure gas within the shell can be also represented as a fraction of the compressor input power. ® Work ofcompression is determined using an isentropic efficiency. 

### Goveming Eauations Six equations represent the physical processes within the shell: Overall Energy Balance W =rh(h4-hl)+QS where W = compressor motor input power QS = rate of heat loss from shell 

### Shell Heat Loss to the Environment 

### QS 

## -JW where 

### .f = correlating parameter 

### Suction Gas HeatBalance 

### rh(h2-hj) _ (1-11m)W+Q3-4 Qs where

TIM = motor efficiency 

### Q3-4 = discharge line heat loss Discharge Line Heat Loss (B - 1)



### (B -2)

(B -3)

Q3-

### 4=aW = rh(h4-h3) (B 

### -4) The thermal processes represented are:

.. The shell heat transfer is correlated to motor inletpower. For the purposes of simplification, 

### it is assumed that the constant ofproportionality is independent ofthe actual operating conditions. Inputvalues for the shell heat loss are based on actual compressor performance data and are typically 70

- 80 percent of the compressor inletpower.

.. The internal heatexchange between the high pressure gas within the discharge line and the low pressure gas within the shell can be also represented as a fraction ofthe compressor inputpower.

.. Work ofcompression is determinedusing an isentropic efficiency. Governing Equations Six equations represent the physical processes within the shell: 

### OverallEnergy Balance

where 

### W 

### = compressor motor inputpower 

### Qs 

# = rate ofheat loss from shell 

### ShellHeat Loss to 

### the Environment

where 

### f = correlating parameter 

### Suction GasHeatBalance

where 

### 11m 

### = motor efficiency Q3-4

## = discharge line heat loss 

### Discharge LineHeatLoss

B-8 (B -1)

(B -2)

(B -3)

(B -4)where a = correlating parameter 

### Com pressor Work Input

il. W -m(h3- ) Compressor Efficiency h3 = h2 + (h3, - hz)

T1$ 

### (B -5)

(B -6)

where rls = isentropic efficiency and the subscripts refers to the enthalpy that would exist if the compression process were reversible and adiabatic and therefore, isentropic. Eqns (B-1) through (B-6) are solved iteratively to determine the enthalpies at the pump inlet, h2, and outlet, h3. The shell discharge condition, h4, is found from:



### (h3 - hi) h4=h1+ a

1+UO'D The refrigerant mass flow rate is then calculated from

(60rpm)'nvdisp m=
vsuc where
rpm = compressor speed in rpm lisp = cylinder displacement volume vs„c = specific volume of refrigerant vapor at the pump inlet valve Iv = volumetric efficiency The volumetric efficiency is determined from:

III, 

### =0.92 1-Cv p3 n-1 Pa (B-7)



### (B -8)

(B -9)

where where



### a. = correlating parameter 

### Compressor WorkInput (B -5) 

### CompressorEfficiency (B -6)
where 

### 'Tls 

### = isentropic efficiency and the subscript

### s refers to the enthalpy that would existifthe compression process were reversible and adiabatic and therefore, isentropic. Eqns (B-1) through (B-6) are solved iteratively to determine the enthalpies at the pump inlet, 

### hb and outlet, 

### h3• The shell discharge condition, 

### h4' is found from: (B -7)

Therefrigerant mass flow rate is then calculated from

. (60rpm)T1v

### dis p 

### m= (B -8)
where
rpm 

## = compressor speed 

### in rpm disp 

## =cylinder displacement volume Valle 

### = specific volume ofrefrigerantvapor atthe pump inletvalve 

### 'Tlv 

### = volumetric efficiency Thevolumetric efficiency is determined from:
(B -9)

where



### B-9Cv = clearance volume, expressed as a fraction of the displacement volume and

n = polytropic exponent, defined as n = 0.97y, where y is the specific

heat capacity ratio of the suction vapor. Model Ingul Parameters The following data are required input to the model:

anutacturer Speed (rpm) 3450 Manufacturer Clearance volume (%) 2 Manufacturer 

### Compression (isentropic) efficiency 1.3 Model Fit Motor-pump efficiency (-) 0.41 Estimate Shell loss (% of power input) 75 Data Discharge tube heat loss 35 Model Fit 

### isplacement (cc or cu-in ...........g..(0.

(% of power input) Data values for most of the parameters are either known from the manufacturer's literature or can be estimated. Model fits have to be carried out to arrive at values for the isentropic efficiency, which has a value greater than one as a result of its definition. Strictly speaking, the so-called isentropic efficiency uses as a reference value for the minimum work input the amount of work required to compress the refrigerant during a reversible and adiabatic (hence, isentropic) process. In the actual compression process, significant heat loss from the refrigerant occurs to the cylinder walls, resulting in a lower refrigerant enthalpy at the end of the compression process compared to the ideal process, thereby corresponding to an efficiency greater than one. This does not imply, however, that the work input is less than the ideal process. 

### B.2.2. Rating Point Compressor Model (EER and Capacity Model) Generally, the only information that can be obtained for a particular compressor are the rating point capacity, motor power input (or EER), displacement volume, and the type of shell cooling that was employed (i.e., static or fan-forced). The model discussed in the following is an empirical model that allows realistic simulation of compressor performance with a minimum of required input parameters. The foundation of this model is comprehensive compressor performance data from AHAM [1] that includes compressor capacity, input power, refrigerant mass flow rate, and refrigerant temperatures at various locations within the compressor, all as a function of evaporating and condensing temperatures and type of compressor shell cooling. Analysis of this data yielded the following important conclusions: and C v 

# = clearance volume, expressed as a fraction ofthe displacement volume



### n 

## = polytropic exponent, defined as 

### n = 0.97"(, where "( is the specific heat capacity ratio ofthe suction vapor. Modellnout Parameters The**fo~owing** data are required input to the model:

Speed (rpm) 3450 Manufacturer Clearance volume (%) 2 Manufacturer Compression (isentropic) efficiency 1.3 Model Fit Motor-pump efficiency (-) 0.41 Estimate Shell loss (% ofpower input) 75 Data Discharge tube heat loss 35 Model Fit (% ofpower input) Data values for most ofthe parameters are either !mown from the manufacturer's literature or can be estimated. Model fits have to be carried out to arrive atvalues for the isentropic efficiency, which has a value greater than one as a result ofits definition. Strictly speaking, the so-called isentropic efficiency uses as a reference value for the minimum workinputthe amount ofworkrequired to compress the refrigerant during a reversible and adiabatic (hence, isentropic) process. 

### In the actual compression process, significant heatloss from the refrigerant occurs to the cylinder walls, resulting in a lower refrigerant enthalpy at the end ofthe compression process compared to the ideal process, thereby corresponding to an efficiency greater than one. This does not imply, however, that the workinput is less than the ideal process. 13.2.2. Rating Point Compressor Model (EER and Capacity Model) Generally, the only information that can be obtained for a particular compressor are the rating pointcapacity. motor power input (or EER), displacement volume, and the type of shell cooling that was employed (i.e., static or fan-forced). The model discussed in the following 

### is an empirical model that allowsrealistic simulation ofcompressor performance 

### with a minimum ofrequired inputparameters. Thefoundation ofthis model is comprehensive compressor performance data from AHAM [1] that includes compressor capacity, inputpower, refrigerant mass flow rate, and refrigerant temperatures at various locations within the compressor, all as a function ofevaporating and condensing temperatures and type ofcompressor shell cooling. Analysis ofthis data yielded the following importantconclusions:



### B-lO1. The compression process behaves like a polytropic process with a polytropic exponent defined as n = 0.97y, where 'y is the refrigerant suction vapor specific heat capacity ratio. 2. The refrigerant vapor temperature at the suction port can be correlated with EER at the rating point. 3. The ratio of compressor discharge temperature and suction port temperature (both in absolute units) is nearly constant at 1.2. 4. The compressor discharge temperature can be correlated with the cylinder discharge temperature, ambient temperature, and the type of compressor cooling. Model in uls The model requires the following information as inputs: compressor type (reciprocating or rotary), compressor capacity at the rating point, EER at the rating point, compressor displacement volume, compressor speed (usually about 3450 - 3500 rpm), and type of compressor cooling. 

### Compressor Parameters At the beginning of the program, the model estimates values for the volumetric andisentropic efficiencies from the compressor rating point capacity and EER using the procedures described below. Compressor Clearance Volume 

### The compressor clearance volume is calculated using the following algorithm. 1. The model calculates the enthalpy of refrigerant vapor and liquid at 32°C (90°F) and at pressures corresponding to the saturation pressures at -23°C (-10°F) and 54°C (130°F). 2. The refrigerant mass flow rate is calculated using the rating point capacity divided by the quantity (vapor enthalpy - liquid enthalpy). 3. The refrigerant vapor temperature at the compressor suction point is calculated using the following correlations: 

### Ts^ = 479.59 - 64.815EER, reciprocating - static cooling, Ts. = 427.84 - 57.895EER, reciprocating - fan cooling, or TSB = 120, rotary. where the temperatures are expressed in Fahrenheit. 

### 1. The compressionprocess behaves like a polytropic process with a polytropic exponent defined as 

### n = 0.97"{, where "{is the refrigerant suction vapor specific heat capacityratio. 2. Therefrigerant vapor temperature at the suction port can be correlated with EER at the rating point. 3. Theratio ofcompressor discharge temperature and suction port temperature (both in absolute units) is nearly constant at 

### 1.2. 4. The compressor discharge temperature can be correlated with the cylinder discharge temperature, ambient temperature, and the type ofcompressor cooling. Model Inputs The model requires the following information as inputs: compressor type (reciprocating orrotary), compressor capacity at the rating point, EER at the rating point, compressor displacement volume, compressor speed (usually about 

### 3450

- 3500 rpm), and type ofcompressor cooling. Compressor Parameters At the beginning ofthe program, the model estimates values for the volumetric and isentropic efficiencies from the compressorrating pointcapacity and EER using theprocedures described below. 

### Compressor Clearance Volume The compressor clearance volume is calculated using the following algorithm. 

### 1. Themodel calculates the enthalpy ofrefrigerantvapor and liquid at 

### 32°C (9OOF) and atpressures corresponding to the saturation pressures at 

### -23°C (-lOOF) and 

### 54°C (130°F). 2. The refrigerant mass flow rate is calculated using the rating pointcapacity divided by the quantity (vapor enthalpy -liquidenthalpy). 3. Therefrigerant vapor temperature atthe compressor suction pointis calculated using thefollowing correlations: 

### Tsuc =479.59

- 

### 64.815EER, reciprocating

- static cooling, 

### Tsuc = 427.84

- 57

.

### 895EER ,reciprocating

- fan cooling, or 

### Tsuc = 120, rotary. 

### where the temperatures are expressed in Fahrenheit

B-U4. The refrigerant density at the suction port is calculated at the suction pressure calculated in Step 1; the suction temperature calculated in Step 3. 5. The volumetric efficiency is calculated using the following relationship:

rn I° 60 • ps,, • rpm • lisp
where

rrc = refrigerant mass flow rate

ps„, = density of the refrigerant suction vapor rpm compressor speed in rpm lisp = compressor displacement volume 6. The clearance volume C, is determined from the following relationship:

rlY = coast 1 - 

### Cv Pis 

# n -1

PsU where const=0.92 and const=l.0 for reciprocating and rotary compressors, respectively, andpdi., and ps,,, are the discharge and suction pressures, respectively. The exponent that best fits the data has been determined to be n = 0.97y. Isentropic Efficiency The isentropic efficiency is determined using the following procedure: 1. Calculate the enthalpy and entropy of the refrigerant vapor at the suction port. 2. Calculate refrigerant enthalpy hdi,,s at the discharge pressure assuming an isentropic process. 

### 3. Calculate the isentropic efficiency as

TL = (hd s, s 

### - hsuc)m'Wr

where W,. is the compressor work at the rating point.

It is assumed that the isentropic efficiency determined in the above equation applies for all operating conditions. 4. Therefrigerant density at the suction port is calculated at the suction pressure calculated in Step 1; the suction temperature calculated in Step 3. 5. The volumetric efficiency is calculated using the following relationship:

where llv = 60 d'



### .Psuc

.rpm· lSP



## m= refrigerant mass flow rate 

### Psuc 

## = density ofthe refrigerant suction vapor rpm =, compressor speed in rpm disp 

### = compressor displacement volume 6. Theclearance volume 

### C v is determined from the following relationship:

where 

### const=O.92 and 

### const=l.O for reciprocating and rotary compressors, respectively, and

### Pdis and

### Psuc are the discharge and suction pressures, respectively. The exponentthat bestfits the data has been determined to be n = 0.97"(. 

### Isentropic Efficiency The isentropic efficiency is determined using the following procedure: 1. Calculate the enthalpy and entropy ofthe refrigerant vapor at the suction port. 2. Calculaterefrigerant enthalpy hdJs,Jl at the discharge pressure assuming an isentropic process. 3. Calculate the isentropic efficiency as

where 

### W, is the compressor work at the rating point.

Itis assumed that the isentropic efficiency determined in the above equation applies for 

### all operating conditions.

B-12Performance Analysis

The above parameters are used in the calculation of compressor performance at conditions off the rating point using the following algorithm. 1. Input the values of the suction and discharge pressures from the main program. 2. Estimate the refrigerant temperature at the suction port using

T5, = T; + 389.59

- 64.815EER , reciprocating

- static cooling,

T5,6C = T, + 337.84 - 57. 895EER, reciprocating - fan cooling, or

T5,6C 

### = T; + 30, rotary. where T; is the temperature of the refrigerant entering the compressor shell, expressed in Fahrenheit. 3. Calculate the refrigerant density, enthalpy and entropy at suction port conditions. 4. Calculate refrigerant enthalpy hdi,,., at the discharge pressure assuming an isentropic process. 5. Calculate the required work input using

hdi, 

### - hs,,, is 6. Using the value of clearance volume determined previously, calculate the volumetric efficiency using the following equation:

11„ = const

where const=0.92 and const=l.0 for reciprocating and rotary compressors, respectively.

### 7. Finally, the mass flow rate and the heat losses from the compressor shell and discharge tube are calculated. B.2.3. Map-Based Compressor Model The third method of calculating compressor performance is a map-based model that uses actual compressor map data applicable to a particular compressor. The user inputs data points for compressor capacity and motor power input as a function of evaporating and condensing temperatures. This data must be at the standard rating condition in which the temperature of the vapor exiting the evaporator (and entering the compressor), the Performance Analysis The above parameters are used in the calculation ofcompressor performance at conditions offthe rating point using the following algorithm. 1. Input the values ofthe suction and discharge pressures from the main program. 2. Estimate the refrigerant temperature at the suction port using 

### Tsuc = 

### T j

### +389.59

- 

### 64.815EER, reciprocating

- static cooling, 

### Tsuc = 

### T j 

### +337.84

- 57

### .895EER,reciprocating

- fan cooling, or 

### Tsuc = 

### T j 

### +30, rotary. where T j is the temperature ofthe refrigerant entering the compressor shell, expressed in Fahrenheit. 3. Calculate the refrigerant density, enthalpy and entropy at suction portconditions. 4. Calculaterefrigerant enthalpy 

### hdis,s at the discharge pressure assuming an isentropic process. 5. Calculate the required work input using 

# w= 

### hdis,s - hsuc 

### 11. 6. Using the value ofclearance volume determined previously, calculate the volumetric efficiency using the following equation:

where 

### const=D.92 and 

### const=1.0 for reciprocating and rotary compressors, respectively. 7. Finally, the mass flow rate and the heatlosses from the compressor shell and discharge 

### tube are calculated. B.2.3. Map-Based Compressor Model The third method ofcalculating compressorperformance is a map-based model that uses actual compressor map data applicable to a particular compressor. The user inputs data points for compressor capacity and motorpowerinput as a function ofevaporating and condensing temperatures. This data mustbe at the standard rating condition in which the temperature ofthe vapor exiting the evaporator (and entering the compressor), the

B-13liquid exiting the condenser and the ambient are all at 32°C (90°F). The data for compressor capacity and motor power input is stored in a user-supplied file with extension .TAB in the following form. 

### TV) Tc(2) Te(1)

cap(1,1) cap(2,1) T e( 2) ® ® 

### cap(1,2) cap(2,2) 1 

### T e( 

### N e) 

### cap(1,Ne) cap(2,Ne) 0

and TT(N^) cap(N,,,1) cap(Nc,N0)

TV) 

### Tc(2) Te(1)

pow(1,1) pow(2,1) T e( 2) pow(1,2) 

### pow(2,2) T0(N0) pow(1,Ne) pow(2,Ne)

0 e Tc(Nc) pow(N,1) pow(Nc)a) where Te and TT are the evaporating and condensing temperatures, respectively. The terms cap andpow refer to the compressor capacity and motor power input, respectively. Units for the data can be input in either °F, Btu/hr, and watts, or °C, kcal/hr, and watts. Up to 20 data points in each of the Te and TT directions can be input, resulting in a maximum of 400 data points for the capacity and compressor power

. The user must specify whether the compressor is a reciprocating or rotary type. The user does not specify the type of refrigerant in the compressor map file. Hence, it is necessary that the user insures that the refrigerant with which the compressor was testedto generate the performance data corresponds to the refrigerant specified in the ERACYC model input data. Upon the initial call of the compressor subroutine the program reads the data file and stores the data internally in arrays. The input variables transferred from the main program include the suction and discharge pressures, and suction and ambient temperatures. Subroutine output variables output to the main program include the refrigerant mass flow rate , compressor power input and shell heat loss. Note that the compressor capacity is not included in the list of output variables

. This is because the capacity as listed in the performance data is determined at fixed values of temperature of vapor exiting the evaporator and liquid exiting the condenser. These conditions do not, in general, exist in an actual refrigerator during normal operation. Thus, use of the capacity as listed in the performance data is incorrect, even for identical evaporating and condensing temperatures

. This subroutine answers the following question: "Given specified compressor suction and discharge pressures and a vapor tempera- 

### liquid exiting the condenser and the ambient are all at 32°C (90°F). The data for compressor capacity and motor power input is storedin a user-supplied file with extension .TAB in the following form. T.(l) T.(2) 

## .. " T.(NJ Til) cap(1,1) cap(l,2) 

## .. .. cap(lN.) Ti 2) cap(2,1) cap(2,2) 0 

### " cap(2N.) 

### • 0 0 0 " "



## .. .. " 

## .. e 

## .. TiN) cap(Nc,l) " 

## .. .. cap(NcN.) 

### and Til) T.(2) 

## .. " T.(NJ Til) pow(1,l) pow(l,2) " " pow(lN e ) Tc(2) pow(2,1) pow(2,2) 

## .. .. pow(2N.)



### • " " 

## .. .. "



## .. " 

### .. 

## .. " 

## .. TiN) pow(N c ,l) 

### .. 

## .. .. pow(NcN.) 

### where T. 

### and Tc 

### are the evaporating and condensing temperatures, respectively. The terms cap 

### andpow

### refer to the compressor capacity and motorpowerinput, respectively. Units for the data can be input in either 

### OF, Btu/hr, and watts, or ·C, kcal/hr, and watts. Up to 20 datapoints in each ofthe Te 

### and Tc 

### directions can be input, resulting in a maximum of400 data points for the capacity and compressorpower. The user must specify whether the compressor is a reciprocating orrotary type. The user does not specify the type ofrefrigerant in the compressor map fIle. Hence, it is necessary that the userinsures that the refrigerant with which the compressor was tested to generate the performance data corresponds to the refrigerant specified in the ERACYC model input data. Upon the initial call ofthe compressor subroutine the program reads the data fIle and stores the data internally in arrays. The input variables transferred from the main program include the suction and discharge pressures, and suction and ambient temperatures. Subroutine output variables output to the main program include the refrigerant mass flow rate, compressorpowerinput and

.shell heat loss. Note that the compressor capacity is not included in the list ofoutput variables. This is because the capacity as listed in the perfonnance data is determined at fixed values of temperature ofvapor exiting the evaporator and liquid exiting the condenser. These conditions do not, in general, exist in an actual refrigerator during normal operation. Thus, use ofthe capacity as listed in the performance data is incorrect, even for identical evaporating andcondensing temperatures. This subroutine answers the following question: "Given specifiedcompressor suction and discharge pressures and a vapor temperaB-14ture at the inlet to compressor shell, what refrigerant mass flow rate can the compressor

produce?" Once the mass flow rate is determined, the value of refrigerant mass flow rate is output to the main program, where the evaporator capacity is determined.The algorithm which is used to determine the refrigerant mass flow rate proceeds as follows: 1. Values for the suction and discharge pressure, refrigerant vapor temperature at the shell, and ambient temperature are input from the main subroutine. 2. The enthalpies of the refrigerant vapor and liquid at the standard rating temperaturesand at the values of suction and discharge pressures are passed from the main program. 3. Based of the values of suction and discharge pressures input from the main program, corresponding values for evaporating and condensing temperatures are determined. 4. Using the values for evaporating and condensing temperatures determined in Step 3, determine values for the compressor capacity and motor power input by interpolation from the stored performance map. 5. The refrigerant mass flow rate is calculated based on the following relationship: refrigerant mass flow rate = (capacity from map) / (vapor enthalpy - liquid enthalpy) where the refrigerant enthalpies are those determined in Step 3. 6. The heat loss from the compressor shell to the ambient is calculated assuming it is afixed fraction of the compressor power input. This fraction is assumed to be 75 percent of the compressor motor power input. 7. Now that the values for the refrigerant mass flow rate, motor power input, and shell heat loss corresponding to the standard rating condition have been determined, thesubroutine corrects for conditions which do not correspond to the standard conditions. The means for determining the amount of correction are based on the data of Reference [2]. The corrections to the refrigerant mass flow rate, motor power input, and shell heat loss are normally small, generally only a few percent of the values at the standard rating condition. 

### 13.3 Cycling LossesCycling of the compressor will normally lead to a reduction in the cycle average efficiency (COP) compared to the steady state value. This will occur due to at least three major effects: • during the on-time the thermal load of the heat exchangers is higher than the cycle average load, leading to increased heat exchanger irreversibilities, ture at the inlet to compressor shell, whatrefrigerant mass flow rate can the compressor produce?" Once the mass flow rate is determined, the value ofrefrigerant mass flow rate is output to the main program, where the evaporator capacity is determined. The algorithm which is used to determine the refrigerant mass flow rate proceeds as follows: 1. Values for the suction and discharge pressure, refrigerant vapor temperature at the shell, and ambient temperature are input from the main subroutine. 2. Theenthalpies ofthe refrigerant vapor and liquid at the standard rating temperatures and at the values of suction and discharge pressures are passed from the main program. 3. Based ofthe values of suction and discharge pressures inputfrom the main program, corresponding values for evaporating and condensing temperatures are determined. 4. Using the values for evaporating and condensing temperatures determined in Step 3, determine values for the compressor capacity and motor powerinput by interpolation from the stored performance map. 5. Therefrigerant mass flow rate is calculated based on the following relationship: refrigerant mass flow rate = (capacity from map) / (vapor enthalpy

- liquid enthalpy) where the refrigerant enthalpies are those determined in Step 3. 6. The heat loss from the compressor shell to the ambient is calculated assuming itis a fixed fraction ofthe compressor power input. This fraction is assumed to be 75 percent ofthe compressor motor powerinput. 7. Now that the values for the refrigerant mass flow rate, motor power input, and shell heat loss corresponding to the standard rating condition have been determined, the subroutine corrects for conditions which do not correspond to the standard conditions. The means for determining the amount ofcorrection are based on the data of Reference [2]. The corrections to the refrigerant mass flow rate, motor power input, and shell heat loss are normally small, generally only a few percent ofthe values at the standard rating condition. B.3 Cycling 

### losses Cycling ofthe compressor will normally lead to a reduction in the cycle average efficiency (COP) compared to the steady state value. This will occur due to at least three major effects:

• during the on-time the thermal load ofthe heat exchangers is higher than the cycle average load, leading to increased heat exchanger irreversibilities,

B-15® when the compressor stops, the pressure ratio rapidly decreases towards one, leading

to flashing of the liquid in the condenser and condensation of liquid in the evaporator,® vapor flows from the condenser to the evaporator where it condenses during the offcycle. To minimize the effects of such losses, the cabinet controls are usually set to ensure a small number of cycles per hour (typically 2 - 3). An alternate approach, suitable for a rotary compressor, is to place a shut-off valve between the condenser and the capillary tube which is shut during the off cycle. Detailed analysis of cycling losses is extremely complicated (and of inherently limited accuracy due to fundamental inabilities to accurately represent all the major mass flow and two-phase heat transfer effects throughout the cycle). As a consequence, a simplecorrelative procedure, partially based on experimental data, has been adopted. Two general situations are represented: 1) normal operation without a shut-off valve, and 2) use of a shut-off valve. B.3.1. Cycling RatesThe degree of cycling loss is dependent on the cycling rate since the controlling phenomena are time dependent. In general, the rate is dependent on the thermal characteristics of the refrigerator cabinet and the control system. The cycling rate is a user input, generally ranging from 1 to 3 cycles per hour. B.3.2. Cycling Losses Without a Valve Janssen, de Wit, and Kuijpers have found that the cycle average COP varies roughly linearly with cycle frequency [3]. From an analysis of the experimental data given in Reference [3], the cycle loss can be estimated as:

Loss = 1.0 %/tcycle For example, at a cycling rate of 2.5 cycles per hour, (tcyc,e = 0.4), the cycle efficiency loss would be about 2.5%. 8.3.3. Cycling Effects with a Shut-off Valve Short cycling with a valve present will actually increase the cycle average COP due to the thermal mass effects of the heat exchangers. In principle, with very massive heat exchangers and short cycling, the theoretical performance should approach that of a variable speed drive system due to the elimination of over- or under-shoot of the heat exchanger temperatures. This effect is illustrated in the experimental data of Philips Research [3]. .. when the compressor stops, the pressure ratio rapidly decreases towards one, leading to flashing ofthe liquid in the condenser and condensation ofliquid in the evaporator,

.. vapor flows from the condenser to the evaporator where 

### it condenses during the offcycle. To minimize the effects of such losses, the cabinet controls are usually set to ensure a small number ofcycles per hour (typically 2 - 3). An alternate approach, suitable for a rotary compressor, is to place a shut-offvalve between the condenser and the capillary tube which is shutduring the off-cycle. Detailed analysis ofcycling losses is extremely complicated (and ofinherently limited accuracy due to fundamental inabilities to accurately represent all the major mass flow and two-phase heat transfer effects throughout the cycle). As a consequence, a simple correlativeprocedure, partially based on experimental data, has been adopted. Two general situations are represented: 1) normal operation without a shut-offvalve, and 2) use ofa shut-offvalve. B.3.1. Cycling Rates The degree ofcycling loss is dependent on the cycling rate since the controlling phenomena are time dependent. In general, the rate is dependent on the thermal characteristics ofthe refrigerator cabinet and the control system. The cycling rate is a user input, generally ranging from 1 to 3 cycles per hour. B.3.2. Cycling Losses Without a Valve Janssen, deWit, and Kuijpers have found that the cycle average COP varies roughly linearly with cycle frequency [3]. From an analysis ofthe experimentaldata given 

### in Reference [3], the cycle loss can be estimated as: Loss = 1.0%/1;;ycle For example, at a cycling rate of2.5 cycles perhour, (tcycle 

## =0.4), the cycle efficiency loss would be about 2.5%. B.3.3. Cycling Effects with a Shut-off Valve Short cycling with a valve present will actually 

### increase the cycle average COP due to the thermal mass effects ofthe heat exchangers. Inprinciple, with very massive heat exchangers and short cycling, the theoretical performance should approach that ofa variable speed drive system due to the elimination ofover- orunder-shoot ofthe heat exchanger temperatures. This effectis illustrated 

### in the experimental data ofPhilips Research [3].

B-16From the experimental data given in [3], the efficiency gain over steady state from the

presence the valve can estimated as:



### Gain = 1.5%/tycie Hence, for a system with 2 cycle/hr, the overall efficiency gain from introducing a microvalve (rotary compressor, only) is approximately (1.0 + 1.5)10.5 = 5%. BA Summary of Help Menu Heat Exchanger Analyses ERA contains subroutines in the help menu to assist the user in determining the heat exchanger input data required for the refrigeration cycle performance calculations. This feature should be used when actual heat transfer performance data for a particular heat exchanger is unavailable, but should not be used in lieu of actual data. A summary ofthe methods used for estimating the heat exchanger performance is presented in the following paragraphs. This summary is very brief, thus the reader is referred to the references at the end of the section and to heat transfer textbooks for further information. The help menu assists the user to estimate both the air-side and refrigerant-side heat transfer coefficients, the refrigerant-side pressure drop, and the heat exchanger surface areas for the following heat exchanger configurations:

Summary of Help Menu Heat Exchanger Configurations condenser forced convection - straight fin-tube, wavy fir-tube, wire=tube

natural convection - vertical plate , hot-wall, wire-tube evaporator forced convection - straight fin-tube, wavy fin-tube

natural convection

- vertical plate, cold-wall, horizontal plate The algorithms for calculating the average heat transfer coefficients follow the general outline presented below:1. Air-side heat transfer coefficients are calculated first. Generally, air-side heat transfer coefficients are reasonably independent of the refrigerant-side conditions. 2. Heat transfer coefficients for single phase refrigerant flow (i.e., refrigerant vapor orliquid) are calculated next. Heat transfer coefficients in this flow regime are essentially independent of the air-side conditions. 3. Heat transfer coefficients and pressure losses for the condensation and evaporating flow regimes are calculated. In general these depend strongly on the air-side heat transfer coefficient. 4. Finally, the average overall heat transfer coefficient based on air

-side surface area corresponding to the single phase vapor, single phase liquid, condensing, and evaporating regimes are calculated

. The pressure drops for the condensing and evaporating heat transfer regimes are also calculated. From the experimental data given in (3], the efficiency gain over steady state from the presence the valve can estimated as: Gain = 

### 1.5%/t"ycle Hence, for a system with 2 cycle/hr, the overall efficiency gain from introducing a microvalve (rotary compressor, only) is approximately 

### (1.0 

### + 1.5)/0.5 

## =5%. 113.4 Summary of Help Menu Heat Exchanger Analyses ERA contains subroutines in the help menu to assist the user in determining the heat exchanger input data required for the refrigeration cycle performance calculations. This feature should be used when actual heat transfer performance data for a particular heat exchanger is unavailable, but should not be used in lieu ofactual data. A summary of the methods used for estimating the heat exchanger performance is presented in the following paragraphs. This summary is very brief, thus the reader is referred to the references at the end ofthe section and to heat transfer textbooks for further information. The help menu assists the user to estimate both the air-side and refrigerant-side heat transfer coefficients, the refrigerant-side pressure drop, and the heat exchanger surface areas for the following heat exchanger configurations:
Summary of Help Menu Heat Exchanger Configurations

## nf.it'!~!!!~::liilj:!:f!!~!I~!!!g~!!:'!:~!::~jjj:!t:.iIR!.~'.::i!i~!~tt!!!

# ..: •.:.:::j::j

..: ..•.;

••..••';.
natural convection
- vertical plate, hot-wall, wire-tube evaporator forced convection
- straight fin-tube, wavy fin-tube natural convection
- vertical plate, cold-wall, horizontal plate
The algorithms for calculating the average heat transfer coefficients follow the general outlinepresented below: 1. Air-side heat transfer coefficients are calculated first. Generally, air-side heattransfer coefficients arereasonably independent ofthe refrigerant-side conditions. 2. Heat transfer coefficients for single phase refrigerant flow (i.e., refrigerant vapor or liquid) are calculated next. Heat transfer coefficients in this flow regime are essentially independent ofthe air-side conditions. 3. Heat transfer coefficients and pressure losses for the condensation and evaporating flow regimes are calculated. In general these depend strongly on the air-side heat transfer coefficient. 4. Finally, the average overall heat transfer coefficient based on air-side surface area corresponding to the singlephase vapor, single phase liquid, condensing, and evaporating regimes are calculated. The pressure drops for the condensing and evaporating heat transfer regimes are also calculated.



### B-17A brief description of the analyses is presented below. B.4.1. Air-Side Heat Transfer Coefficients Forced Convection - Fin-Tube Air-side performance for fin-tube heat exchangers is calculated using methods similar to those found in Reference [4]. Depending on user defined values for heat exchangergeometry (i.e. tube diameter, tube spacing, fin spacing, etc.) and air flow rate, the program calculates the air-side heat exchanger area (which is required for the ERACYC model input) and the geometric and fluid dynamic parameters required for the heat transfer calculation. The program uses empirical heat transfer correlations to calculate the Nusselt number of the form



### Nu=CRe'Prb (R -10) The heat transfer coefficient is calculated from a relation of the form

Nu kair h h (R-11)

d Separate correlations are used for the straight and wavy fin types and are based on several sets of data for each fin type presented in Reference [4]. The Reynolds number Re is defined in terms of the hydraulic diameter dh of the heat exchanger (calculated internally by the program) and Pr is the Prandtl number of the fluid. The fin efficiency is calculated based on the heat transfer coefficient calculated in Eqn. (E-11), and is used in the calculation for the average air-side U-value. Forced Convection - Wire-TubeIt is assumed that the heat exchanger orientation is such that the wires are aligned parallel with the air flow direction and the condenser tubes are perpendicular to the air flow direction. The user provides information regarding diameter and spacing of the condenser tubing and wires, and the air flow rate. Heat transfer coefficients for the wires and the condenser tubes are calculated using correlations of the same form as (E-10) and (B-11). Radiative Component A radiative component of heat transfer is added to the convective components discussed above. The radiative component is calculated by linearizing the equations for radiationheat transfer, from which a radiative heat transfer coefficient can be defined and calculated using the following equation:



### hr,^d= 4acT; ave (B - 12) A briefdescription ofthe analyses is presented below. B.4.1. Air-Side Heat Transfer Coefficients Forced Convection

- Fin-Tube Air-side perfonnance for fin-tube heat exchangers is calculated using methods similar to those found in Reference [4]. Depending on user defined values for heat exchanger geometry (i.e. tube diameter, tube spacing, fin spacing, etc.) and air flow rate, the program calculates the air-side heat exchanger area (which is required for the ERACYC model input) and the geometric and fluid dynamic parameters required for the heat transfer calculation. The program uses empirical heat transfer correlations to calculate the Nusselt number ofthe fonn (B -10) The heat transfer coefficient is calculated from a relation ofthe fonn (B -11) Separate correlations are used for the straight and wavy fin types and are based on several sets ofdata for each fin type presented in Reference [4]. The Reynolds number Re is defined in tenns ofthe hydraulic diameter d h ofthe heat exchanger (calculated internally by the program) and Pr is the Prandtl number ofthe fluid. The fin efficiency is calculated based on the heat transfer coefficient calculated in Eqn. (B-ll), and is used in the calculation for the average air-side U-value. Forced Convection
- Wire-Tube Itis assumed that the heat exchanger orientation is such that the wires are aligned parallel with the air flow direction and the condenser tubes are perpendicular to the air flow direction. The user provides information regarding diameter and spacing ofthe condenser tubing and wires, and the air flow rate. Heat transfer coefficients for the wires and the condenser tubes are calculated using correlations ofthe same form as (B-lO) and (B-11). Radiative Component A radiative component ofheat transfer is added to the convective components discussed above. The radiative component is calculated by linearizing the equations for radiation heat transfer, from which a radiative heat transfer coefficientcan be defmed and calculated using the following equation: (B -12)

B-18where Tr,QVe in Eqn. (B- 12) is the refrigerant saturation temperature in absolute temperature units and r is the Stefan-Boltzman constant which has a value of 5.67 x 10-8 W/m2-K. The surface emittance, E, is assumed equal to 0.8 for the condenser surfaces and equal to 0.2 for the evaporator surfaces. Natural Convection The heat transfer coefficients for natural convection heat exchangers are composed of two components; convective and radiative. The total heat transfer coefficient is the sum of these two components, or



### h = hnc + hrad (B -13)Correlations for air which are appropriate for the specified geometry are used to calculate the convective component, and have the form

hnc = C 

### I Tr,ave - Ti, 10.33 (B -14) More detailed descriptions of the correlations can be found in References [5, 6]. The term I T,,ave - Ti,.

aI is the absolute value of the difference between the average refrigerant saturation temperature and the bulk air temperature. The air temperature corresponds tothe ambient (i.e., room) air temperature for analyzing a condenser and the cabinet temperature for analyzing an evaporator. The constant C in Eqn. (B- 14) depends on the heat exchanger geometry. Geometries included in these analyses are a vertical plate condenser, hot-wall condenser, vertical wire-tube condenser, vertical plate evaporator, cold-wall evaporator, and a horizontal plate evaporator. The user provides data for each heat exchanger type as requested by the help menu. B.4.2. Refrigerant-Side Heat Transfer Coefficients and Pressure Drops Single Phase Refrigerant FlowThe single phase refrigerant heat transfer coefficients are calculated assuming fullydeveloped laminar or turbulent flow. The Nusselt number correlations used in this analysis are Nu =3.66 (B -15) for laminar flow, and

Nu = 0.023Reo.sPro.a (B - 16) for turbulent flow.In most instances, the pressure drops are small compared to the pressure drop in the condensation and evaporating flow regimes and are therefore ignored. where Tr,ave in Eqn. (B-12) is the refrigerant saturation temperature in absolute temperature units and 0' is the Stefan-Boltzman constant which has a value of 5.67 x 10-8 W/m2-K. The surface emittance, 

### e, is assumed equal to 0.8 for the condenser surfaces and equal to 0.2 for the evaporator surfaces. Natural Convection The heattransfer coefficients for natural convection heat exchangers are composed of two components; convective and radiative. The total heat transfer coefficient is the sum ofthese two components, or (B -13)
Correlations for air which are appropriate for the specified geometry are used to calculate the convective component, and have the form hnc = C 

### IT r .ave - T air ,0.33 (B -14)
More detailed descriptions ofthe correlations can be found in References [5, 6]. The term 

## IT r•ave - T air 

## Iis the absolute value ofthe difference between the average refrigerant saturation temperature and the bulk air temperature. The air temperature corresponds to the ambient (i.e., room) air temperature for analyzing a condenser and the cabinet temperaturefor analyzing an evaporator. Theconstant C in Eqn. (B-14) depends on the heat exchanger geometry. Geometries included in these analyses are a vertical plate condenser, hot-wall condenser, vertical wire-tube condenser, vertical plate evaporator, cold-wall evaporator, and a horizontal plate evaporator. The userprovides data for each heat exchanger type asrequested by the help menu. B.4.2. Refrigerant-Side Heat Transfer Coefficients and Pressure Drops Single Phase Refrigerant Flow The singlephaserefrigerant heat transfer coefficients are calculated assuming fullydeveloped laminar or turbulentflow. The Nusselt number correlations used in this analysis are Nu =3.66 (B -15) for 

### laminar flow, and (B -16) for turbulent flow. In most instances, the pressure drops are small compared to the pressure drop in the condensation and evaporating flow regimes and are therefore ignored.

B-19

### Condensation Heat Transfer Regime Heat transfer coefficients and pressure drops are calculated simultaneously in the condensing flow regime. The analysis begins at saturated vapor and marches stepwise downstream, calculating the local heat transfer coefficient and pressure gradient until the point at which complete condensation has occurred, from which the average heat transfer coefficient and total pressure drop can be determined

. The equations and algorithms for calculating the condensation heat transfer coefficients and two-phase pressure drop are too complex to be presented here, but can be found in References [7 - 10]. Evaporation Heat Transfer Regime The analysis for the evaporating heat transfer regime is very similar to that of for the condensation regime. The major difference is that much simpler equations are used to calculate the average evaporating heat transfer coefficient, eliminating the need for a stepwise calculation. However, the pressure drop in the evaporating heat transfer regime is calculated by marching stepwise downstream, calculating the local pressure gradient, and summing the local pressure drops to calculated the total pressure drop. The equations for calculating the average evaporating heat transfer coefficient are takenfrom Reference [11] while the pressure drop is calculated using the method from Reference [10]. 

### BA3. Fluid Properties The help menu contains refrigerant thermodynamic and transport properties for six purerefrigerants; CFC-12, C- 134a, C- 152a, HC-290- (propane), HC-270 (cyclopropane), and HCFC-22. For both pure fluids and mixtures in which the properties are not tabulated, the thermophysical properties are calculated based on the critical properties(which are stored in ERA) using various molecular models. The methods of thermophysical property calculation used in ERA are outlined in Reference [12]. Use of the help menu to calculate the heat transfer coefficients for NARMs should be done with caution, as NARMs generally behave very differently than pure fluids. The heat transfer coefficient correlations used in the help menu models are derived for pure fluids, and thus generally do not apply to NARMs. The properties of dry air are calculated in the program based on the user defined value of air temperature, assuming atmospheric pressure. B.5 Corrections for Hot-Wall Condenser or Cold- Wall Evaporator Corrections are required to the cabinet loads output from CAB.EXE to account for thepresence of a cold-wall evaporator and/or hot-wall condenser. Two factors must be considered: ® The presence of the heat exchanger over a portion of the wall reduces the thickness of the insulation over the same area. The menu program calculates the UAs of the cabinet walls containing the heat exchangers and inputs these values to the cycle model in file CYCLE.DAT. Condensation Heat Transfer Regime Heat transfer coefficients and pressure drops are calculated simultaneously in the condensing flow regime. The analysis begins at saturated vapor and marches stepwise downstream, calculating the local heat transfer coefficient and pressure gradient until the point at which complete condensation has occurred, from which the average heat transfer coefficient and total pressure drop can be determined. The equations and algorithms for calculating the condensation heat transfer coefficients and two-phase pressure drop are too complex to be presented here, butcan be found in References [7

- 10]. Evaporation Heat Transfer Regime The analysis for the evaporating heat transfer regime is very similar to that offor the condensationregime. The major difference is that much simpler equations are used to calculate the average evaporating heat transfer coefficient, eliminating the need for a stepwise calculation. However, the pressure drop in the evaporating heat transfer regime is calculated by marching stepwise downstream, calculating the local pressure gradient, and summing the local pressure drops to calculated the total pressure drop. The equations for calculating the average evaporating heat transfer coefficient are taken from Reference [11] while the pressure drop is calculated using the method from Reference [10]. B.4.3. Fluid Properties The help menu contains refrigerantthermodynamic and transportproperties for six pure refrigerants; CFC-12, HFC-134a, HFC-152a, HC-29o- (propane), HC-270 (cyclopropane), and HCFC-22. For both pure fluids and mixtures in which the properties are not tabulated, the thermophysical properties are calculated based on the critical properties (which are stored in ERA) using various molecular models. The methods ofthermophysical property calculation used in ERA are outlined in Reference [12]. Use ofthe help menu to calculate the heattransfer coefficients for NARMs should bedone with caution, as NARMs generally behave very differently than pure fluids. The heat transfer coefficient correlations used in the help menu models are derived for pure fluids, and thus generally do not apply to NARMs. Theproperties ofdry air are calculated in the program based on the user defmed value of air temperature, assuming atmospheric pressure. B.5 Corrections for Hot-Wall Condenser or Cold-WalilEvaporator Corrections are required to the cabinetloads output from CAB.EXE to account for the presence ofa cold-wall evaporator and/or hot-wall Gondenser. Two factors mustbe considered:

.. The presence ofthe heat exchanger over a portion ofthe wall reduces the thickness ofthe insulation over the same area. The menu program calculates the UAs ofthe cabinet walls containing the heat exchangers and inputs these values to the cycle model in me CYCLE.DAT.

B-20During the on-cycle period (when the compressor is operating) the environment

communicates with the heat exchanger through the insulation. This results in an incremental refrigeration load and a change in the cabinet load during the on-cycle period. As an example, assume that a cold-wall evaporator is used in the fresh food section of a dual evaporator cycle. If the thermal conductance of the area of the wall containing the evaporator is written:

UA_FF_EVP = UA of fresh food section wall evaporator then the additional refrigeration load on the evaporator is



### AQe = UA_FF_EVP (Ta - T0) where Ta = room temperature and Te = evaporator temperature.During the time the compressor is operating, the evaporator effectively isolates this portion of the cabinet wall from the environment. This will result in a correction to the duty cycle (compressor on-time):

Duty Cycle = Cabinet Load / CAP' where CAP` = CAP + AQe - UA_FF_EVP (Ta - Tom) where T = fresh food cabinet temperature and CAP is the evaporator capacity in the absence of the additional heat input to the evaporator through the insulation. Similar equations hold for the freezer evaporator. The presence of a hot-wall condenser will have similar effects on the cabinet loads and refrigeration cycle behavior. During the time the compressor is running the outside wallwill be warmer than the ambient, which will result in additional heat flow into the cabinet. As a consequence, the duty cycle will be lengthened by the additional cabinet heat load. For example, if the condenser is in the walls of a fresh food section, the duty cycle becomes: Duty = Cabinet-Load/(CAP' + AQ) where AQ = UA_FF_CND (TT - TO

UA_FF CND = UA value ofportion of wall containing condenser TT = condenser temperature .. During the on-cycleperiod (when the compressor is operating) the environment communicates with the heatexchanger through the insulation. This results in an incremental refrigeration load and a change in the cabinet load during the on-cycle period. As an example. assume that a cold-wall evaporator is used in the fresh food section ofa dual evaporator cycle. Ifthe thermal conductance ofthe area ofthe wall containing the evaporator is**writt~m:** UA_FF _EVP 

## =U A offresh food section wall evaporator then the additional refrigeration load on the evaporator is

where Ta

## =room temperature and Te

## =evaporator temperature. During the time the compressor is operating, the evaporator effectively isolates this portion ofthe cabinet wall from the environment. This will result in a correction to the duty cycle (compressor on-time): Duty Cycle = CabinecLoad

### I CAp· where

where TfF = fresh food cabinet temperature and CAPis the evaporator capacity in the absence ofthe additional heat input to the evaporator through the insulation. Similar equations hold for the freezer evaporator. Thepresence ofa hot-wall condenser will have similar effects on the cabinet loads and refrigeration cycle behavior. During the time the compressor is running the outside wall will be warmer than the ambient, which will result in additional heat flow into the cabinet. As a consequence, the duty cycle will be lengthened by the additional cabinet heat load. Forexample, ifthe condenser is in the walls ofa fresh food section, the duty cycle becomes: Duty = CabinecLoad/(CAP· 

### +AQ) where

UA_FF

_CND = U A value ofportion ofwall containing condenser 

### Tc = condenser temperature

B-21Matching Evaporator Capacities and Cabinet Loads The overall analysis of daily energy use takes place in four steps: ® Step 1: Calculate cabinet loads assuming fixed cabinet temperatures ® Step 2: Calculate cycle parameters for given cabinet air temperature ® Step 3: Perform adjustments to match cabinet loads and evaporator capacity ® Step 4: Calculate compressor run time and the net energy consumption Steps 2 and 3 are normally done iteratively since there will often be an imbalance between the loads of the two cabinets and the corresponding cooling rates. The method for matching the capacities and loads depends on the refrigeration cycle andthe control option. This is discussed below for the three basic cycles: 1) single evaporator - single compressor cycle; 2) dual-loop cycle; 3) dual evaporator cycle (with one compressor). Note that the Lorenz cycle is a subset of the dual evaporator cycle. B.6.1. Single Evaporator Cycle The single evaporator cycle uses an air baffle arrangement to deliver cool air to bothcompartments from the single evaporator, located in the back of the freezer compartment. It is assumed that the user has properly set the baffle, or that an electronically controlled baffle is used, to deliver the necessary air to each compartment to simultaneously meet the two cabinet loads at the assumed setpoints. The cooling rate of each compartment is given by:

Q = rhCp f (TTF -Tout) Qz=rhCp (1 -f) (Trz-Tau) where m Cp = mass flow - specific heat of air across the evaporator

f = fraction of air going to fresh food compartment Tout = temperature of air leaving the evaporator coil The inlet air temperature of the coil, and the net evaporator capacity, must satisfy:

Ti. = fT +(1-f)TFZ Capacity = rhCp (Ti. - Taut) 

### The equations are solved simultaneously to determine the fraction of air going to the fresh food section (typically 10 - 15%) and the inlet air temperature to the evaporator. B.S Matching Evaporator Capacities and Cabinet Loads 

### The overall analysis ofdaily energy use takes place in four steps: " Step 1: Calculate cabinet loads assuming fixed cabinet temperatures " Step 2: Calculate cycle parameters for given cabinet air 

### temperature " Step 3: 

### Perform adjustments to match cabinet loads and evaporator capacity

e 

### Step 4: 

### Calculate compressor run time and the net energy consumption Steps 2 

### and 3 

### are normally done iteratively since there will often be an imbalance between the loads ofthe two cabinets and the corresponding cooling rates. The method for matching the capacities and loads depends on the refrigeration cycle and the control option. This is discussed below for the three basic cycles: 1) 

### single evaporator

- single compressor cycle; 2) 

### dual-loop cycle; 3) 

### dual evaporator cycle (with one compressor). Note that the Lorenz cycle is a subset ofthe dual evaporator cycle. B.6.1. Single Evaporator Cycle 

### The single evaporator cycle uses an air 

### baffle arrangement to deliver cool air 

### to both compartments from the single evaporator, located in the back ofthe freezer compartment. It is assumed that the user has properly set the baffle, or that an electronically controlled baffle is used, to deliver the necessary air 

### to each compartment to simultaneously meet the two cabinet loads at the assumed setpoints. The cooling rate ofeach compartmentis given by: 

## <k

## =

# me; f (TFF - 

### TouJ 

## <k=

# me;, (1
- 1) 

### (TFZ - 

### TouJ where 

### mC p 

## = mass flow

- specific heat ofair 

### across the evaporator f 

## = fraction ofair 

### going to fresh food compartment Tout 

## = temperature ofair leaving the evaporator coil The inlet air 

### temperature ofthe coil, and the net evaporator capacity, must satisfy:

Capacity 

## = mC p 

### (Tin

- TouJ The equations are solved simultaneously to determine the fraction ofair 

### going to the fresh food section (typically 10

- 15%) and the inlet air 

### temperature to the evaporator.

B-22B.6.2. Dual Loop

The dual loop cycle employes two separate refrigeration loops and controls, one for each compartment. They are solved separately, and the energy consumption values combined to establish the overall consumption level. B.6.3. Dual Evaporator Cycle This is the most complex cycle from a controls standpoint. Although fans could be used in both compartments and cycled on and off to effectively couple or de-couple the evaporator from the cabinet air, it is assumed that at least one of these evaporators will be a natural convection type. Hence, there will almost always be an imbalance between the delivered cooling rates and the needs of the individual compartments. ERA provides 5 options for dealing with this: ® Allow imbalance -- the summary output will note an imbalance when one occurs. A second run can then be made with an adjustment in parameters in an attempt toreduce the imbalance below some level. For example, most current Chinese refrigerator/freezer designs use a resistance heater in the fresh food section to artificially add a heat load when necessary to keep the compressor running to ensure that the freezer compartment is adequately refrigerated. ® Allow the fresh food section cabinet temperature to float when the compressor is controlled by the freezer set point. Corrections to the fresh food section cabinet heat load and temperature are made until the cabinet loads are in balance with the relative evaporator capacities. ® Allow the freezer temperature to float when the compressor is controlled by the fresh food section set point. The freezer cabinet load is adjusted, along with the freezertemperature, to achieve a balance between the cabinet loads and evaporator capacities. ® Mathematically adjust the areas of the two evaporators to achieve the balance. The algorithm adopted maintains total evaporator area, while adjusting the fraction in each compartment

. This is, of course, not possible in a hardware configuration. However, it yields information useful to a researcher or designer about the proportion of evaporator areas required to achieve a correct balance. 

### ® Bypass one of the evaporators during a portion of the cycle. B.7 Variable Speed Operation Variable speed control is one means of achieving efficiency improvements. Motor speed is modulated to maintain essentially constant operation of the compressor at areduced capacity that nearly matches the cabinet load. Both the physically based (lossefficiency) model and rating point (EER-capacity) model for the compressor allow specification of reduced speed. Because of the complex phenomena involved throughout the refrigeration cycle, capacity is not linear with respect to speed, but varies with some fractional power of the speed. These variations are taken into account by the compres- B.6.2. Dual Loop The dual loop cycleemployes two separate refrigeration loops and controls, one for each compartment. They are solved separately, and the energy consumption values combined to establish the overall consumption level. B.6.3. Dual Evaporator Cycle This is the most complex cyclefrom a controls standpoint. Although fans could be used inboth compartments and cycled on and offto effectively couple or de-couple the evaporator from the cabinet 

### air, itis assumed that atleast one ofthese evaporators will be a natural convection type. Hence, there will almost always be an imbalance between the delivered cooling rates and the needs ofthe individual compartments. ERAprovides 5 options for dealing with this: " Allow imbalance

-- the summary output will note an imbalance when one occurs. A second run can then be made with an adjustment in parameters in an attempt to reduce the imbalancebelow some level. Forexample, most current Chinese refrigerator/freezer designs use a resistance heater in the fresh food section to artificially add a heat load when necessary to keep the compressorrunning to ensure that the freezer compartmentis adequately refrigerated. " Allow the fresh food section cabinet temperature to float when the compressor is controlled by thefreezer setpoint. Corrections to the fresh food section cabinetheat load and temperature are made until the cabinet loads are in balance with the relative evaporator capacities.

.. Allow the freezer temperature to float when the compressor is controlled by the fresh food section setpoint. The freezer cabinet load is adjusted, along with the freezer temperature, to achieve a balance between the cabinet loads and evaporator capacities.

.. Mathematically adjustthe areas ofthe two evaporators to achieve the balance. The algorithm adopted maintains total evaporator area, while adjusting the fraction in each compartment. This is, ofcourse, notpossible in a hardware configuration. However, it yields information useful to a researcher or designer aboutthe proportion ofevaporator areas required to achieve a correct balance.

.. Bypass one ofthe evaporators during a portion ofthe cycle. 

### B.7 Variable Speed Operation Variable speed control is one means ofachieving efficiency improvements. Motor speedis modulated to maintain essentially constant operation ofthe compressor at a reduced capacity thatnearly matches the cabinet load. Both the physically based (lossefficiency) model and rating point (EER-:capacity) model for the compressor allow specification ofreduced speed. Because ofthe complex phenomena involved throughout the refrigeration cycle, capacity is not linear with respect to speed, but varies with some fractional power ofthe speed. These variations are taken into account by the compres

### B-23sor models. Hence, the program user merely need specify a change in the speed and ERA will determine a corresponding capacity. Because of lubrication issues as well as motor efficiency concerns, the minimum desirable speed would be 25 - 40% of normal operating speed. Electric motors show efficiency changes with speed [ 13]. ERA does not automaticallyadjust for motor efficiency, but assumes the program user will account for this by inputting a lower EER level or lower pump-motor efficiency parameters, depending on the compressor model selected. Electronics losses will partially affect gains realized by variable speed operation. These losses occur in the speed control device which will be located outside the refrigerator cabinet. Two means for accounting for the electronics losses are provided: 1) specify the losses directly when using the loss-efficiency compressor model, 2) incorporate these losses into a reduced effective EER when using the EER-capacity compressor model. Reference [13] discusses the nature and magnitude of such losses. In order to realize the efficiency potential of variable speed control, reduced wattagefans must be utilized since the fans will also be operated nearly continuously. In addition, it may be advantageous to vary the fan speed to reduce the air flow over the heat exchanger since the dominant heat transfer resistance may be on the refrigerant side at reduced mass flow. A simple model is employed to estimate the variation in air flow rate and fan power as a function of speed [14]:

Air flow -speed Fan power a (speed)3 A calculation assist menu is available to automatically scale the air flow and fan power. If a variable speed analysis is carried out, the calculation assist menu for evaporator and condenser heat transfer should be utilized. The effects of both reduced refrigerant mass flow and variable speed fan induced air flow will be taken into account. 

### References 1. Data received from AHAM on results of round-robbin testing of two reciprocating domestic refrigerator compressors using CFC- 12 refrigerant. 2. Meyer, W. M., and Thompson, H. D., "An experimental Investigation Into heat Transfer to the Suction Gas in a Low-Side Hermetic Refrigeration Compressor", Proceedings of the 1990 International Compressor Engineering Conference, Purdue University, West Lafayette Indiana, July 17-20, 1990, pp 908-916. 3. M.J.P. Janssen, J.A. deWit, and L.J.M. Kuijpers, "Cycling Losses in Domestic Appliances: An Experimental and Theoretical Analysis," Proceedings of the 1990 USNC/HR - Purdue Refrigeration Conference, pp. 90-98, July, 1990. sor models. Hence, the program user merely need specify a change in the speed and ERA will determine a corresponding capacity. Because oflubrication issues as well as motor efficiency concerns, the minimum desirable speed would be 25

- 40% ofnormal operating speed. Electric motors show efficiency changes with speed [13]. ERA does not automatically adjustfor motor efficiency, but assumes the program user will account for this by inputting a lower EER level or lower pump-motor efficiency parameters, depending on the compressor model selected. Electronics losses will partially affect gains realized by variable speed operation. These losses occur in the speed control device which will be located outside the refrigerator cabinet. Two means for accounting for the electronics losses are provided: 1) specify the losses directly when using the loss-efficiency compressor model, 2) incorporate these losses into a reduced effective EER when using the EER-capacity compressor model. Reference [13] discusses the nature and magnitude of such losses. In order to realize the efficiency potential ofvariable speed control, reduced wattage fans must be utilized since the fans will also be operated nearly continuously. In addition, itmay be advantageous to vary the fan speed to reduce the 

### air flow over the heat exchanger since the dominant heat transfer resistance may be on the refrigerant side at reduced mass flow. A simple model is employed to estimate the variation in 

### air flow rate and fan power as a function of speed [14]: Air flow oc speed Fanpower oc (speed)3 A calculation assist menu is available to automatically scale the 

### air flow and fan power. Ifa variable speed analysis is carried out, the calculation assist menu for evaporator and condenser heat transfer should be utilized. The effects ofboth reduced refrigerant mass flow and variable speed fan induced 

### air flow will be taken into account. B.8 References 1. Datareceived from AHAM on results ofround-robbin testing oftwo reciprocating domestic refrigerator compressors using CFC-12 refrigerant. 2. Meyer, W. M., and Thompson, H. D., 

### "An experimental Investigation Into heat Transfer to the Suction Gas in a Low-Side Hermetic Refrigeration Compressor", Proceedings ofthe 1990 International Compressor Engineering Conference, Purdue University, WestLafayette Indiana, July 17-20, 1990, pp 908-916. 3. M.J.P. Janssen, J.A. deWit, and L.J.M. Kuijpers, "Cycling Losses in Domestic Appliances: 

### An Experimental and Theoretical Analysis," Proceedings ofthe 1990 USNC/llR

- Purdue Refrigeration Conference, 

### pp. 90-98, July, 1990.

B-244. Kays, W. M., London, A. L., Compact Heat Exchangers, McGraw-Hill Book Company, New York, third edition, 1984. 5. ASH RAE 1989 Handbook of Fundamentals, published by the American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., Atlanta, GA, 1989. 6. Krieth, F., Pringiffles of Het Transfer, third edition, Intex Press, Inc., New York, 1973. 7. Dittus, F. W., and Boelter, L. M. K., "Heat Transfer in Automobile Radiators of the Tubular type", Publications in Engineering, University of California, Berkeley, 2, pp. 443-461, 1930. 8. Ackers, W. W., and Rosson, H. F., "Condensation Inside a Horizontal Tube", Chemical Engineering Progress Symposium Series, 5 ,L, 30, 1960. 9. Ackers, W. W., Dean, H. A., and Crosser, D. K., "Condensing Heat Transfer Within Horizontal Tubes", Chemical Engineering Progress Symposium Series, 55, 29, 1959.10. Lockhart, R. W., and Martinelli, R. C., "Proposed Correlation of Data for Isothermal Two-Phase, Two-Component Flow in Pipes", Chemical Engineering Progress, 4455, 1, pp. 39-48. 11. Pierre, Bo, Ivtlteknisk Tidskrint, ., May 1957, p. 129. 12. Merriam, R. L., and Mathias, S., "Evaluation of Advanced Vapor Compression Cycles for Use With Nonazeotropic Refrigerant Mixtures", report by Arthur D. Little, Inc. for Oak Ridge National Laboratory, January 1988. 13 Dickmann, J., and McMahon, E, "State of the Art Survey of Motor Technology Applicable to Hermetic Compressors for Domestic Refrigerator/Freezers," Draft Report to the U.S. EPA by Arthur D. Little, Inc., 1991. 14 ASHRAE Equipment Handbook, "Fans". 4. Kays, W. M., London, A. L., Compact Heat Exchangers, McGraw-Hill Book Company, New York, third edition, 1984. 5. ASHRAE 1989 Handbook ofFundamentals, published by the American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., Atlanta, GA, 1989. 

### 6. Krieth, 

### E, Principles ofHeat Transfer, third edition, Intex Press, Inc., New York, 1973. 

### 7. Dittus, 

### E W., and Boelter, L. M. K., "HeatTransfer 

### in Automobile Radiators ofthe Tubular type", Publications in Engineering, University ofCalifornia, Berkeley,,2, pp. 443-461, 1930. 8. Ackers, W. W., and Rosson, H. E, "Condensation Inside a Horizontal Tube", Chemical Engineering Progress Symposium Series,j,Q, 30, 1960. 9. Ackers, W. W., Dean, H. A., and Crosser, D. K., "Condensing Heat Transfer Within Horizontal Tubes", Chemical Engineering Progress Symposium Series,.5..5., 29, 1959. 10. Lockhart, R. W., and Martinelli, R. 

## c., "Proposed Correlation ofData for Isothermal Two-Phase, Two-ComponentFlow in Pipes", Chemical Engineering Progress,**~,** 1, pp. 39-48. 11. Pierre, Bo, Kytlteknisk**Tidskript,~,** May 1957, p. 129. 12. Merriam, R. 

### L., and Mathias, S., "Evaluation ofAdvanced Vapor Compression Cycles for Use With Nonazeotropic Refrigerant Mixtures", report by Arthur D. Little, Inc. for Oak Ridge National Laboratory, January 1988. 13 Dickmann, J., and McMahon, E, "State ofthe Art Survey ofMotor Technology Applicable to Hermetic Compressors for Domestic RefrigeratorlFreezers," Draft Report to the U.S. EPA by Arthur D. Little, Inc., 1991. 14 ASHRAE EquipmentHandbook, "Pans".

B-25APPENDIX C 71-77 D,P.®:® FILES: on®< ..%a T INPUT

C. I Introduction C-2 C.2 SummarY of Sample Input Data C-2 C.3 Reference C-2 C.l Introduction APPENDIXC SAMPLE DATA FilES: MULTIPLE PATHWAYS DATA INPUT

C.2 Summary ofSample Input Data C.3 Reference



### C-l C-2 C-2 C-2C.1 Introduction

The multiple pathways analyses of alternate design concepts for super efficient refrigerators utilized the ERA program to estimate daily and annual energy use. Descriptions of the refrigerator designs, and results of the model analyses, are summarized in the reference document [1]. To facilitate further analyses along the lines utilized in the Multiple Pathways analysis effort, all of the data files developed and input to ERA are provided on diskettes accompanying ERA.As recommended in Section 8, a naming convention has been adopted to facilitate cataloging the files. The general strategy for naming the files is given below: Model Design 1991 Baseline Design 1993 CFC-Free Design A Top-Mount Model_A 

### A_1993 B Top-Mount Model_B 

### B1993 C Top-Mount 

### Model_C C_1993 D Top-Mount Model_D 

### D_1993 E Bottom-Mount Model_E 

### E_1993
F Side-by-Side Model_F F_1993 Eight character names for the remaining files are built up of 4 character fields: The first character designates the baseline model (A - F). ® The second and third characters are the path shown in the Multiple Pathways report (1, 1A, 2, ..., 10) ® The fourth and fifth characters are the step in the path , numbered from the baseline unit (e.g., 01, 02, ..., 12). The remaining three characters designate the design feature studied by the particular run (see Table C-1)
C.2 Summary of Sample Input DataTables C-2 to C-18 list the sample data files with a short description of the design feature of interest to the run. Note that the analyses progress along the line of sequential changes, where each new case incorporates the features of previous steps along the path.


### C.3 Reference 1. "Multiple Pathways to Super Efficient Refrigerators," U.S. EPA, Global Change Division, Office of Atmospheric Programs, 1993. C.1 Introduction The multiple pathways analyses ofalternate design concepts for super efficient refrigerators utilized the ERA program to estimate daily and annual energy use. Descriptions of the refrigerator designs, and results ofthe model analyses, are summarized in the reference document [1]. To facilitate further analyses along the lines utilized in the Multiple Pathways analysis effort, all ofthe data files developed and input to ERA are provided on diskettes accompanying ERA. As recommended in Section 8, a naming convention has been adopted to facilitate cataloging the meso The general strategy for naming the mes is given below: Model Design 1991 BaselineDesign 1993 CFC-FreeDesign A Top-Mount Model_A A_1993 B Top-Mount Model_B B_1993 C Top-Mount Model_C C_1993 D Top-Mount Model_D D_1993 E Bottom-Mount Model_E E_1993 F Side-by-Side ModeCF F_1993 Eight character names for the remaining files are built up of4 character fields:

G The first character designates the baseline model (A

- F). " The second and third characters 

### are the path shown in the Multiple Pathways report (1, lA, 2,

..., 10) " The fourth and fifth characters 

### are the step in the path, numbered from the baseline unit (e.g., 01, 02,

..., 12). " The remaining three characters designate the design feature studied by the particular run (see Table C-l)

C.2 Summary of Sample Input Data Tables C-2 to C-18 list the sample data files with a short description ofthe design feature ofinterest to the run. Note that the analyses progress along the line of sequential changes, where each new case incorporates the features ofprevious steps along the path.
C.3 Reference 1. "Multiple Pathways to SuperEfficient Refrigerators," U.S. EPA, Global Change Division, Office ofAtmospheric Programs, 1993.

C-2

### Tattle C-1. Three Character Code Designations for Design Feature

ADF CBI CCP Adaptive defrost

Carbon black insulation Cyclopropane refrigerant CMP Higher EER compressor CSC Current small compressor C50 Increase condenser area 50% DCC DC condenser fan ICE DC evaporator fan DCF DC evaporator and condenser fans DLR Use refrigerant R152a in freezer section

and refrigerant R 142b in fresh food section DRI Add insulation to doors E50 Increase evaporator area 50% FSC Future small compressors FST Change Defrost timer G25 Cut gasket loss 25% G50 Cut gasket loss to 50% HEF High efficient fans (PSC type) HRI High-R gas filled insulation INO Add 1/2 inch insulation all around IN1 Add 1 inch insulation all around IN2 Add 2 inches insulation all around INS Add insulation everywhere except to doors LLF Liquid line cabinet flange heat LLM Liquid line mullion heat LRZ Lorenz cycle MCI Microcell insulation REF Refrigerant 152a SHV Shut-off valve VCC Variable capacity compressor VCM Vacuum insulation VLF Vapor line heat to cabinet flange 

### Table Cal. Three Character Code Designations for Design Feature ADF Adaptive defrost CBI Carbon black insulation CCP Cyclopropane refrigerant CMP HigherEER compressor CSC Current small compressor C50 Increase condenser area 50% DCC DC condenser fan DCE DC evaporator fan DCF DC evaporator and condenserfans DLR Use refrigerant R152a in freezer section and refrigerant R142b in fresh food. section DRI Add insulation to doors E50 Increase evaporator area 50% FSC Future small compressors FST Change Defrost timer 025 Cut gasket loss 25% 050 Cut gasket loss to 50% HEF High efficient fans (PSC type) HRI High-R gas filled insulation INO Add 1/2 inch insulation all around INI Add 1inch insulation all around IN2 Add 2 inches insulation all around INS Add insulation everywhere except to doors LLF Liquid line cabinet flange heat LLM Liquid line mullion heat LRZ Lorenz cycle MCI Microcell insulation REF Refrigerant I52a SHV Shut-offvalve VCC Variable capacity compressor VCM Vacuum insulation VLF Vapor line heat to cabinet flange

C-3Table C-2. Pathway 1:

1993-CFC Model_D 1993 D_1993 1 D1_01G25 2 D2_02G50 3 D 1_03LLM 4 DI-04C 5 D1_O5DRI 6 D1_06MCI 7 D1_071N1 8 DI-08 F 9 D1_09DCE 10 D1_10DCC

Table C-3. Pathway IA:
, tep l7^ait "a 1993-CFC Model_I 1993 D_1993 1 D1_01G25 2 D2_02G50 3 D 1_03LLM 4 D1_04C 5 D1_05DRI 6 D 1_06MCI 7 D1A07ADF 8 D lA08IN2 9 D 1 A09DCE 10 D1AlODCC Single Evaporator Cycle Current Technologies with Increased Insulation Model D Prc^otype Rlefrigeraior/Free r Deev! 1993 prototype design with CFCs 1993 prototype, with HT-C-134a refrigerant and HCFC-blown insulation Cut gasket heat leak by 25% Cut gasket heat leak by 50% from baseline value Replace mullion heater with liquid line heat Use 5.5 EER compressor (was 5.3 EER) Add 3/ 4 inch insulation to both doors Employ micro

-cell insulation Add 1 inch insulation all around (including doors) Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) Use DC evaporator fan Use DC condenser fan

Single Evaporator Cycle Current Technologies with Thick Wall Cablraet Model Prototype Refrigerator/Freezer 1993 prototype design with CFCs 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Cut gasket heat leak by 25% Cut gasket heat leak by 50% from baseline value Replace mullion heater with liquid line heat Use 5.5 EER compressor (was 5.3 EER) Add 3/4 inch insulation to both doors Employ micro-cell insulation Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) Add 2 inches insulation all around Use DC evaporator fan Use DC condenser fan 

### Table C-2. Pathway 1:



### step> IJiiMFile 1993-CFC

### MOd~Lb 1993 D_1993 1 D1_OlG25 2 D2_02G50 3 D1_03LLM 4 Dl_04CMP 5 Dl_05DRI 6 Dl_06MCI 7 DL07IN1 8 Dl_08ADF 9 Dl_09DCE 10 DLlODCC 

### Single Evaporator Cycle CurrentTechnologies with IncreasedInsulation Model D Prototype Refrigerator/Freezer 

## IJdci;pit(Ji;< .......••.•....
.....•..•.••.......••.•..••. 1993

## protot~~a~sign~ith 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Cut gasket heat leak by 25% Cut gasket heat leak by 50% from baseline value Replace mullion heater with liquid line heat Use 5.5 EER compressor (was 5.3 EER) Add 3/4 inch insulation to both doors Employ micro-cell insulation Add 1inch insulation all around (including doors) Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) Use DC evaporator fan Use DC condenser fan



### Table C-3. Pathway lA: 

### Single Evaporator Cycle CurrentTechnologies with Thick Wan Cabinet Model D Prototype RefrigeratoriFreezer

1993 D_1993 1993 prototype, with HFC-134arefrigerant and 

### 1 

### 2 3 4 5 

### 6 7 8 9 10 Dl_01G25 D2_02G50 Dl_03LLM D1_04CMP D1_05DRI Dl_06MCI D1A07ADF DIA08IN2 D1A09DCE D1AlODCC HCFC-blown insulation Cut gasket heat leak by 25% Cut gasket heat leak by 50% from baseline value Replace mullion heater with liquid line heat Use 5.5 EERcompressor (was 5.3 EER) Add 3/4 inch insulation to both doors Employ micro-cell insulation Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) Add 2 inches insulation all around Use DC evaporator fan Use DC condenser fan

C-4Table C®4. Pathway 2: Single Evaporator Cycle Timprove Components and Auxiliaries Mode-17 B Fnaguiype Refriger. -Cor/Freez?r
1991 

### Model_B 1991 prototype design 

### I E2_O1C Use 5.00 EER compressor (was 4

.57 EER) 2 

### E2_02FST Replace 2 watt defrost timer with 1/4 watt outside cabinet 3 IB2_03IN0 Add 1/2 insulation all around 4 E2_04DRI Add 1/2 insulation to doors 1993 

### E

_1993 1993 prototype, with C

- 134a refrigerant and HCFC bl i l i

own on - nsu at 6 B2_06LLM Replace mullion heater with liquid line heat 7 E2_07C Use 5.3 EER rotary compressor 

### 8 E2_08SHV Add shut-off valve (with rotary compressor) 9 

### B2_09C50 Increase condenser area 50% 10 E2

_10ADF Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) 11 B2

_11E50 Increase evaporator area 50% 12 E2_12DCF Use DC fans



### Table C-5. Pathway 3: Single Evaporator Cycle Improved Compressor and Cabinet Model C Prototype Refrigerator/Freezer 1991 Model_C 1991 prototype design 1 C3_O1LLF Replace freezer flange heater with liquid line heat 2 C3_02C Use 5.00 EER compressor (was 4.85 EER) 

### 3 C3_03DCE DC evaporator fan 4 C3 04DRI Add 1 inch insulation to both doors 1993 C1993 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation 

### 6 C3_06G25 Cut gasket heat leak by 25% 7 C3_07C Use 5.3 EER rotary compressor 8 C3_O8DRI Add 1 inch insulation to both doors 9 C3_09INS Add 1 inch insulation everywhere except doors 10 C3_10MCI Employ micro-cell insulation 11 C3_1 IADF Use adaptive defrost (reduce frequency by 74%) 

### Table C-4. Pathway 2:



## $itp···<·

..·**1~9i** 

### . 1 2 

### 3 4 

### 1993 6 7 8 9 10 11 12 B2_03INO B2_04DRI B_1993 B2_06LLM B2_07CMP B2_08SHV B2_09C50 B2_lOADF B2_11E50 B2_12DCF



### Table CDS. Pathway 3:

1 

### 2 

### 3 4 1993 

### 6 7 8 

### 9 10 11 C3_01LLF C3_02CMP C3_03DCE C3_04DRI C_1993 C3_06G25 C3_07CMP C3_08DRI C3_09INS C3_lOMCI C3_11ADF 

### Single Evaporator Cycle Improved Components and Auxiliaries Model B Prototype Refrigerator/Freezer

Use 5.00EER compressor (was 4.57 EER) Replace 2 watt defrost timer with 1/4 watt outside cabinet Add 1/2 insulation all around Add 

### 1/2 insulation to doors 1993 prototype, with HFC-134arefrigerant and HCFC-blown insulation Replace mullion heater with liquid line heat Use 5.3 EER rotary compressor Add shut-offvalve (with rotary compressor) Increase condenser area 50% Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) Increase evaporator area 50% UscDC fans



### Single Evaporator Cycle Improved Compressor and Cabinet Model C Prototype Refrigerator/Freezer
prototype**"'''''''~l'>''** Replace freezer flange heater with liquid line heat Use 5.00EER compressor (was 4.85 EER) DC evaporator fan Add 1inch insulation to both doors 1993 prototype, with HFC-134arefrigerant and HCFC-blown insulation Cut gasket heat leak by 25% Use 5.3 EER rotary compressor Add 

### 1inch insulation to both doors Add 1 inch insulation everywhere except doors Employ micro-cell insulation Use adaptive defrost (reduce frequency by 74%)

C-5Table C-6. Pathway 3A: Single Evaporator Cycle Improved Compressor and Cabinet viCh Felder ReNgerantr 

### Model C Prototype Reffr!gerator/Freezer Sled Ducre Fff'c ? emc pt ®u 1991 iodel_C 1991 prototype design 1 C3_O1LL.F Replace freezer flange heater with liquid line heat 2 C3_02C Use 5.00 EER compressor (was 4.85 EER) 3 C3_03DCE DC evaporator fan 4 C3_04DRI Add 1 inch insulation to both doors 

### 1993 C_1993 1993 prototype, with C-134a refrigerant and i l i HCFC bl on - nsu at own 

### 6 C3_0 25 Cut gasket heat leak by 25% 7 

### C3AO7CCP Replace IBC-134a with RC-270 (cyclopropane) 8 C3AO8CMP Use 5.3 EER rotary compressor 9 

### C3AO9MCI Employ micro-cell insulation 10 C3AlODRI Add 1 inch insulation to both doors 11 C3A11ADF Use adaptive defrost (reduce frequency by 74%) 12 C3A12INS Add 1 inch insulation everywhere except doors

Table C-7

. Pathway 4: Single Evaporator Cycle Current Technologies with Advanced Insulation Model A Prototype Reffrigerator/Freezer

1991 

### Model_b. 1991 prototype design 1 A4_O1C Use 5.3 EER compressor (was 4.55 EER) 2 A4_02DRI Add 3/4 insulation to both doors 3 A4_03VLF Replace door flange heater with vapor line heat from compressor exit 

### 1993 A_1993 1993 prototype, with HFC- 134a refrigerant and HCFC bl i

i l own - nsu at on 5 A4_05G50 Cut gasket heat leak by 50% from baseline value 6 

### A4_06CMP Use 5.5 EER compressor 7 A4_07DCE Use DC evaporator fan 8 A4_08DCC Use DC condenser fan 9 A4_O9IIRI 50% coverage with high-R gas filled insulation 10 A4_10HRI 80% coverage with high-R gas filled insulation 

### Table C-6. Pathway 3A: Single Evaporator Cycle



## SUp 1991 1 2 

### 3 4 1993 

### 6 7 8 9 lO 

### 11 12 

### Improved Compressor and Cabinet with Better Refrigerant Model C Prototype RefrigeratoriFreezer 

## Diz'tQPitiF**l)~~criiJtion** 

## .. 

# MOdeLc 1991 prototype design C3_01LLF Replace freezer flange heater with liquid line heat C3_02CMP Use 5.00EER compressor (was 4.85 EER) C3_03DCE DC evaporator fan C3_04DRI Add 1 inch insulation to both doors C_I993 1993 prototype, with HFC-134arefrigerant and C3_06G25 C3A07CCP C3A08CMP C3A09MCI C3AI0DRI C3A11ADF C3A12INS HCFC-blown insulation Cut gasket heat leak by 25% Replace HFC-134a with RC-270 (cyclopropane) Use 5.3 EER rotary compressor Employ micro-cell insulation Add 1 inch insulation to both doors Use adaptive defrost (reduce frequency by 74%) Add 1 inch insulation everywhere except doors



### Table C-7. Pathway 4: Single Evaporator Cycle

1 2 

### 3 1993 

### 5 6 7 8 9 lO A4_01CMP A4_02DRI A4_03VLF

A4_05G50 A4_06CMP A4_07DCE A4_08DCC A4_09HRI A4_lOHRI 

### CurrentTechnologies with Advanced Insulation Model A Prototype Refrigerator/Freezer prototype**~_~.,..,**.. Use 5.3 EER compressor (was 4.55 EER) Add 3/4 insulation to both doors Replace door flange heater with vapor line heat from compressor exit 1993 prototype, with HFC-134arefrigerant and HCFC-blown insulation Cut gasket heat leak by 50% from baseline value Use 5.5 EER compressor Use DC evaporator fan UseDC condenser fan 50% coverage with high-R gas filled insulation 80% coverage with high-R gas filled insulation

C-6Table C-8. Pathway 4A: - Single Evaporator Cycle Current Technologies with Improved Insulation Model A Prototype Refrigerator/Freezer
1991 

### Model_A 1991 prototype design 1 

### A4_01C Use 5.3 EER compressor (was 4.55 EER) 2 A4_02DRI Add 3/4 insulation to both doors 3 A4_03 VLF Replace door flange heater with vapor line heat from compressor exit 1993 A_1993 1993 prototype, with C-134a refrigerant and HCFC bl i l i

own nsu
- at on 5 A4_05G50 Cut gasket heat leak by 50% from baseline value 

### 6 A4_06C Use 5.5 EER compressor 7 

### A4AO7REF Change to refrigerant RFC-152a 8 A4AO8MCI Employ micro-cell insulation 9 A4AO9CEI Use carbon black additive to insulation 10 A4A 10 F Use high efficiency fans (PSC type) 11 A4A 11DCF Use DC fans

Table C-9. Pathway 5: Single Evaporator Cycle Advanced Cycle and Insulation Technologies Model D Prototype Refrigerator/Freezer seep D a 9 a f7i JeSciipdon 1993-CFC Model_D 1993 prototype design with CFCs 1993 D_1993 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation 1 D5_01G50 Cut gasket heat leak by 50% from baseline value 2 D5_02C Use 5.5 EER compressor (was 5.3 EER) 3 D5_03ADF Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) 4 D5_04VCC Variable capacity linear compressor (6.5 EER) 5 D5_05DCF Use DC fans 6 D5_06VCM 50% coverage with 1 inch thick r-1.6 vacuum panel foamed into wall 7 D5_07VCM 80% coverage with 1 inch thick r-1.6 vacuum panel foamed into wall 

### Table C-S. Pathway 4A:

. Single Evaporator Cycle**S~p**

1991 1 2 3 1993 5 

### 6 7 

### 8 9 

### 10 11 

### Current Technologies with Improved Insulation Model A Prototype RefrigeratoriFreezer



## .**1JiJtd~il~>** 

## .

## liestripdiiii

.. ·· .......

ModeLA 1991 prototyPedesign

.. A4_01CMP Use 5.3 EER compressor (was 4.55 EER) A4_02DRI Add 3/4 insulation to both doors A4_03VLF Replace door flange heater with vapor line heat from

A4_05G50 A4_06CMP A4A07REF A4A08MCI A4A09CBI A4AlOHEF A4AIIDCF compressor exit 1993 prototype, with HFC-134arefrigerant and HCFC-blown insulation Cut gasket heat leak by 50% from baseline value Use 5.5 EER compressor Change to refrigerant HFC-152a Employ micro-cell insulation Use carbon black additive to insulation Use high efficiency fans (PSC type) Use DC fans



### Table C-9. Pathway 5: Single Evaporator Cycle



# .:**<$~ii:** 

# <ilJiiiiiFiit:· 1993-CFCMOrle[O···

. 1993 D_1993 1 D5_01G50 2 D5_02CMP 3 D5_03ADF 4 D5_04VCC 5 D5_05DCF 6 D5_06VCM 7 D5_07VCM 

### Advanced Cycle and Insulation Technologies Model D Prototype Refrigerator/Freezer prototype**UV~".I'.U** 1993 prototype, with HFC-134arefrigerant and HCFC-blown insulation Cut gasket heat leak by 50% from baseline value Use 5.5 EER compressor (was 5.3 EER) Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) Variable capacity linear compressor (6.5 EER) Use DC fans 50% coverage with 1 inch thick r-1.6 vacuum panel foamed into wall 80% coverage with 1 inch thick r-1.6 vacuum panel foamed into wall

C-7Table C-10. Pathway 6: Lorenz Cycle Improved Technologies

n^ ( J l f l' 'W Model B Prototype Refrigerator/Freezer

e ceeylo%L 1991 

### odei_B 1991 prototype design 1 B2_O1CMP Use 5.00 EER compressor (was 4.57 EER) 2 B2_02FST Replace 2 watt defrost timer with 1/4 watt outside cabinet 3 

### B2_03IN0 Add 1/2 insulation all around 4 B2_ DRI Add 1/2 insulation to doors 1993 

### B_1993 1993 prototype, with HFC-134a refrigerant and bl l i HCFC i

own nsu on - at 6 

### B6_06L Lorenz cycle with ternary blend 7 B6_07G25 Reduce gasket heat leak by 25% 

### 8 B6_08C Use 5.3 EER rotary compressor 9 

### B6_09SHV Add shut-off valve (with rotary compressor) 10 B6 10CBI Use carbon black additive to insulation 11 B6_1 1ADF Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) 12 B6_12DCE Use DC evaporator fan 13 

### B6_13DCC Use DC condenser fan

Table C-11. Pathway 7: Lorenz Cycle Improved Components and Advanced Insulation Model C Prototype Refrigerator/Freezer 

### Seep D, 94 Fa' Desc apia^rre 1991 

### 1 ode1_C 1991 prototype design 1 C3_01LLF Replace freezer flange heater with liquid line heat 2 

### C3_02C Use 5.00 EER compressor (Was 4.85 EER) 

### 3 C3_03DCE DC evaporator fan 4 C3_04DRI Add 1 inch insulation to both doors 1993 C_1993 1993 prototype, with HFC-134a refrigerant and HCFC bl l

i i own - nsu at on 6 C7_06LRZ Lorenz cycle with ternary 

### 7 C7_07G50 Cut gasket heat leak by 50% from baseline value 8 C7_08ADF Use adaptive defrost (reduce frequency by 74%) 9 C3_09DCC DC condenser fan 10 C3_10VCM 50% coverage with 1 inch thick r-1.6 vacuum panel foamed into wall 11 C3_11VCM 80% coverage with 1 inch thick r-1.6 vacuum panel foamed into wall 

### Table C-IO. Pathway 6:



# StlP 1991 1 2 

### 3 4 1993 

### 6 7 8 9 10 11 12 13 

# ·PoUJFile

.·Mod6CB

B2_01CMP B2_02FST B2_03INO B2_04DRI B_1993 B6_06LRZ B6_07G25 B6_08CMP B6_09SHV B6_1OCBI B6_11ADF B6_12DCE B6_13DCC



### Table C-ll. Pathway 7:

1 2 

### 3 4 1993 

### 6 

### 7 8 9 10 11 C3_01LLF C3_02CMP C3_03DCE C3_04DRI C_1993 C7_06LRZ C7_07G50 C7_08ADF C3_09DCC C3_1OVCM 

### Lorenz Cycle Improved Technologies Model B Prototype Refrigerator/Freezer 

### Description

. 1991 prototype design Use 5.00 EER compressor (was 4.57 EER) Replace 2 watt defrost timer with 1/4 watt outside cabinet Add 1/2 insulation all around Add 1/2 insulation to doors 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Lorenz cycle with ternary blend Reduce gasket heat leak by 25% Use 5.3 EER rotary compressor Add shut-offvalve (with rotary compressor) Use carbon black additive to insulation Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) Use DC evaporator fan Use DC condenser fan



### Lorenz Cycle Improved Components and Advanced Insulation Model C Prototype RefrigeratorlFreezer prototype

____,..,__ Replace freezer flange heater with liquid line heat Use 5.00EER compressor (was 4.85 EER) DC evaporator fan Add 1inch insulation to both doors 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Lorenz cycle with ternary Cut gasket heat leak by 50% from baseline value Use adaptive defrost (reduce frequency by 74%) DC condenser fan 50% coverage with 1 inch thickr-1.6 vacuum panel foamed into wall 80% coverage with 1 inch thick r-1.6 vacuum panel foamed into wall

C-8Table C

-12° Pathway 8: Lorenz Cycle Best Cycle Components and Auxiliaries Model A Prctotype Refrigera or/Fr r 

### 1991 M el_A 

### 1991 prot

# otype design 1 A4_01C 

### Use 5.3 EER compressor (was 4.55 EER) 2 A4_02DRI Add 3/ 4 insulation to both doors 3 A4-03VLF Replace door flange heater with vapor line heat from compressor exit 

### 1993 A_1993 1993 prototype, with HFC-134a refrigerant and i HCFC bl l ti

- own nsu on

a 5 

### A8_05L Lorenz cycle with ternary 6 

### A8_06C Use 5.5 EER compressor 

### 7 A8_07C Use 6.0 EER compressor (ECM Motor) 8 A8_08DCF Use DC fans 9 

### A8_09ADF Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer)

Table C-13° Pathway 8A: Lorenz Cycle Current Techologies with Thick Wall Cabinet Model A Prototype Refrigerator/Freezer 

### 1991 

### Model_A 1991 prototype design 1 A4_01 C Use 5.3 EER compressor (was 4.55 EER) 2 A4_02DRI Add 3/4 insulation to both doors 3 

### A4_03VLF Replace door flange heater with vapor line heat from compressor exit 

### 1993 A_1993 1993 prototype, with HFC-134a refrigerant and HCFC bl i l ti

own on - nsu a 

### 5 A8_05LRZ Lorenz cycle with ternary 6 A8A 25 Reduce gasket heat leak by 25% 7 A8AO7CMP Use 5.5 EER compressor 8 A8AO8DCF Use DC fans 9 A8A09IN2 Add 2 inches insulation all around 10 A8AlOADF Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) 

### Table C-12. Pathway 8:

1 

### 2 

### 3 1993 

### 5 

### 6 7 8 9 A4_01CMP A4_02DRI A4_03VLF A_1993 A8_05LRZ A8_06CMP A8_07CMP A8_08DCF A8_09ADF 

### Lorenz Cycle Best Cycle Components and Auxiliaries Model A Prototype Refrigerator/Freezer

Use 5.3 EER compressor (was 4.55 EER) Add 3/4 insulation to both doors Replace doorflange heater with vapor line heat from compressor exit 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Lorenz cycle with ternary Use 5.5 EERcompressor Use 

### 6.0 EER compressor (ECM Motor) Use DC fans Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer)



### Table C-13. Pathway SA: Lorenz Cycle

1 

### 2 

### 3 1993 

### 5 6 7 

### 8 9 

### 10 A4_OlCMP A4_02DRI A4_03VLF A_1993 A8_05LRZ A8A06G25 A8A07CMP A8A08DCF A8A09IN2 A8A1OADF 

### Current Techologies with Thick Wall Cabinet Model A Prototype RefrigeratorlFreezer prototype**U"''''~;<'U** Use 53 EER compressor (was 4.55 EER) Add 3/4 insulation to both doors Replace doorflange heater with vapor line heat from compressor exit 1993 prototype, with HFC-134arefrigerant and HCFC-blown insulation Lorenz cycle with ternary Reduce gasket heat leak by 25% Use 5.5 EER compressor Use DC fans Add 2 inches insulation 

### all around Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer)

C-9Table C-14. Pathway 9: Dual L oop Cycle Improved Components and Thick Wall Cabinet Model D Prototype Refrigerator/Fr zer 1993-CFC Model_D 1993 prototype design with CFCs 1993 D_1993 1993 prototype, with C

- 134a refrigerant and HCFC-blown insulation 1 D9_01CSC Dual-loop with current small compressors 2 D9_02FSC Use future small compressors (4.6 and 5.1 EER) 3 D9_03DCF Use DC fans (all four fans) 4 D9_04DLR C- 152a in freezer loop and HCFC-142b in fresh food loop 5 D9_05G50 Cut gasket heat leak by 50% from baseline value 6 D9_06MCI Employ micro

-cell insulation 7 D9_07CEI Use carbon black additive to insulation 8 D9_08IN1 Add 1 inch insulation all around 9 D9_09ADF Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) 10 D9 10IN2 Add 1 inch more of insulation all around

Table C-15. Pathway 10: Dual Loop Cycle Improved Components with Advanced Insulation Model A Prototype Refrigerator/Freezer 

### sop tDzk Filc Description 1991 iViodel_A 1991 prototype design 1 A4_01C Use 5.3 EER compressor (was 4.55 EER) 2 A4_02DRI Add 3/4 insulation to both doors 3 A4_03VLF Replace door flange heater with vapor line heat from compressor exit 1993 A_1993 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation 5 A1005FSC Dual loop with future small compressors, HFC-152a in freezer loop 

### and HCFC- 142b in fresh food loop 6 A1006G50 Cut gasket heat leak by 50% from baseline value 7 A1007ADF Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) 8 A1008DCE Use DC evaporator fans (2) 9 A1009DCC Use DC condenser fans (2) 10 A1010HRI 50% coverage with high-R gas filled insulation 11 A1011HRI 80% coverage with high-R gas filled insulation 

### Table C-14. Pathway 9:



## s.Iii ..•.. DiltiiFili 'P

. . ... 

### i993-CFC 

### ModeLD 1993 D_1993 1 D9_OlCSC 2 D9_02FSC 3 D9_03DCF 4 D9_04DLR 5 D9_05G50 6 D9_06MCI 7 D9_07CBI 8 D9_08IN1 9 D9_09ADF 10 D9_10IN2 

### Dual Loop Cycle Improved Components and Thick Wall Cabinet Model D Prototype Refrigerator/Freezer 

### Descriptutn

...... ..(> • <:i\ •
..i·:. 1993 prototype design 

## with**C:FC~·** 

### . 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Dual-loop with current small compressors Use future small compressors (4.6 and 5.1 EER) Use DC fans (all four fans) HFC-152a in freezer loop and HCFC-142b in fresh food loop Cut gasket heat leak by 50% from baseline value Employ micro-cell insulation Use carbon black additive to insulation Add 1inch insulation all around Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) Add 1inch more ofinsulation all around



### Table C-1S. Pathway 10: Dual Loop Cycle

1 A4_OlCMP 2 A4_02DRI 3 A4_03VLF 1993 A_1993 5 Al005FSC

6 AlOO6G50 7 AlOO7ADF 8 AlOO8DCE 9 Al009DCC 10 AI010HRI 

### 11 A1011HRI 

### Improved Components with Advanced Insulation Model APrototype Refrigerator/Freezer prototype Use 5.3 EER compressor (was 4.55 EER) Add 3/4 insulation to both doors Replace door flange heater with vapor line heat from compressor exit 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Dual loop with future small compressors, HFC-152a in freezer loop and HCFC-142b in fresh food loop Cut gasket heat leak by 50% from baseline value Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) Use DC evaporator fans (2) Use DC condenser fans (2) 50% coverage with high-R gas filled insulation 80% coverage with high-R gas filled insulation



### C-1OTable C

-16. Pathway 11: Single Evaporator Cycle Most Cost Eff

ective Conventional Technologies Vad l D Protclype'eTrigerator/Fr r 1993-CFC Model_D 1993 prototype design with CFCs 1993 D_1993 1993 prototype, with C- 134a refrigerant and HCFC-blown insulation 1 D1101G25 Reduce gasket heat leak by 25% 2 D 1102LLM Replace mullion heater with liquid line heat 3 D1103C Use 5

.5 EER compressor (was 5.3 EER) 4 D1104MCI Employ micro

-cell insulation 5 D1105CBI Use carbon black additive to insulation 6 D l 106DCE Use DC evaporator fan 7 D 1107 F Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer)



### Table C-17. Pathway 12: Lorenz Cycle Most Cost Effective Advanced T echnologies Model D Prototype Refrigerator/Freezer c A ^? D Tcripti o 

### 1993-CFC Model_D 1993 prototype design with CFCs 1993 D_1993 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation 

### 1 D1201LRZ Lorenz cycle with propane and HCFC-123 2 D12O2CMP Use 5.5 EER compressor (was 5.3 EER) 3 D 1203DCF Use DC fans with low speed evaporator fan 4 D1204ADF Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) 5 D 1205LLM Replace mullion heater with liquid line heat 6 D1206050 Cut gasket heat leak by 50% from baseline value 7 D1207VCM 80% coverage with 1 inch thick r-1.6 vacuum panel foamed into wall 8 D1208VCC Variable capacity linear compressor (6.5 EER) 

### Table C-16. Pathway 11: Single Evaporator Cycle

1993 1 

### 2 3 4 

### 5 

### 6 7 D_1993 DllOIG25 Dl102LLM D1103CMP D1104MCI D1105CBI D1106DCE Dl107ADF 

### Most Cost Effective Conventional Technologies Model D Prototype RefrigeratorlFreezer

1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Reduce gasket heat leakby 25% Replace mullion heater with liquid line heat Use 5.5 EER compressor (was 5.3 EER) Employ micro-cell insulation Use carbon black additive to insulation Use DC evaporator fan Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer)



### Table C-17. Pathway 12: Lorenz Cycle

1993 1 

### 2 

### 3 4 

### 5 6 

### 7 8 D1201LRZ D1202CMP D1203DCF D1204ADF D1205LLM D1206G50 D1207VCM D1208VCC 

### Most Cost Effective Advanced Technologies Model D Prototype RefrigeratorlFreezer
prototype**"'''''~'41S''** 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Lorenz cycle with propane and HCFC-123 Use 

### 5.5 EER compressor (was 

### 5.3 EER) Use DC fans with low speed evaporator fan Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) Replace mullion heater with liquid line heat Cut gasket heat leak by 50% from baseline value 80% coverage with 1 inch thickr-1.6 vacuum panel foamed into wall Variable capacity linear compressor (6.5 EER)

C-llTable C

- 1S. Pathway 13: Single Evaporator Cycle 

### Most Coss E tive ConvenC!®aE TecGrano.Eogies Model E Bu'Lltlayn-A/u(DunI 

## '7 - 11 1^41111 311, Z' 47 _^ 19'90 Mel_E 1993-CFC Model_E3 1990 prototype 

### design with 

# CFCs 1993 prototype design with CFCs 1993 E_1993 1993 prototype, with HIFC-134a refrigerant and HCFC-blown insulation 

### 1 E1301G25 Reduce gasket heat leak by 25% 2 E 1302C Use 5.5 EER compressor (was 5.15 EER) 3 E 1303MCI Employ micro-cell insulation 4 E 1304CEI Use carbon black additive to insulation 

### 5 E 1305D Use DC evaporator fan 

### 6 E 130b F Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer)

Table C-19. Pathway 14: Single Evaporator Cycle 

### Most Cost Effective Conventional Technologies Model F Side-by-Side Refrigerator/Freezer ILq 1990 Model _F 1990 prototype design with CFCs 

### 1993-CFC Model_F3 1993 prototype design with CFCs 

### 1993 F_1993 1993 prototype, with HFC-134a refrigerant and wn insulation HCFC-bl 1 F1401G25 o Reduce gasket heat leak by 25% 

### 2 F1402C Use 5.5 EER compressor (was 5.3 EER) 3 F 1403MCI Employ micro-cell insulation 4 F1404CBI Use carbon black additive to insulation 

### 5 F 1405DCE Use DC evaporator fan 6 F 1406ADF Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer) 

### Table CoIS. Pathway 13: Single Evaporator Cycle

1 2 

### 3 4 

### 5 

### 6 E1301G25 E1302CMP E1303MCI E1304CBI E1305DCE E1306ADF



### Table C-19. Pathway 14:

1993-CFC ModeCF3 1993 F_1993 1 

### 2 

### 3 4 5 6 F1401G25 F1402CMP F1403MCI F1404CBI F1405DCE F1406ADF 

### Most Cost Effective Conventional Technologies Model E Bottom-Mount RefrigeratorlFreezer prototype

__u.,..,•• 

### 1993 prototype design with CFCs 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Reduce gasket heat leak by 25% Use 5.5 EER compressor (was 5.15 EER) Employ micro-cell insulation Use carbon black additive to insulation Use DC evaporator fan Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer)



### Single Evaporator Cycle Most Cost Effective Conventional Technologies Model F Side-by-Side RefrigeratorlFreezer prototype**Uo;;,"'L~U** 

### 1993 prototype design with CFCs 1993 prototype, with HFC-134a refrigerant and HCFC-blown insulation Reduce gasket heat leak by 25% Use 5.5 EER compressor (was 5.3 EER) Employ micro-cell insulation Use carbon black additive to insulation Use DC evaporator fan Use adaptive defrost (reduce frequency by 74% and use lower wattage defrost timer)

C-12