1



# Revised Draft Analysis of U.S. Commercial Supermarket Refrigeration Systems

Prepared by ICF Consulting for

U.S. EPA’s Stratospheric Protection Division

November 30 , 20052 

## Table of Contents

1. Executive Summary

................................ ................................ ................................ ............................ 3 2. Introduction

................................ ................................ ................................ ................................ ......... 4 3. Direct Expansion (DX) Systems

................................ ................................ ................................ ......... 7 3.1. Description

................................ ................................ ................................ ................................ ... 7 3.2. Penetration of Technology

................................ ................................ ................................ ........... 7 3.3. Refrigerant Type and Charge Size

................................ ................................ ............................... 8 3.4. Typical Leak Rates and Direct Emissions

................................ ................................ ................... 8 3.5. Energy Consumption

................................ ................................ ................................ .................... 9 3. 6. Capital and Installation Costs

................................ ................................ ................................ ....... 9 4. Secondary Loop Systems

................................ ................................ ................................ .................... 9 4.1. Description

................................ ................................ ................................ ................................ ... 9 4.2. Penetration of Technology

................................ ................................ ................................ ......... 10 4.3. Refrigerant Type and Charge Size

................................ ................................ ............................. 10 4.4. Typical Leak Rates and Direct Emissions

................................ ................................ ................. 11 4.5. Energy Consumption

................................ ................................ ................................ .................. 12 4.6. Capital and Installation Costs

................................ ................................ ................................ ..... 14 5. Distributed Systems

................................ ................................ ................................ .......................... 15 5.1. Description

................................ ................................ ................................ ................................ . 15 5.2. Penetration of Technology

................................ ................................ ................................ ......... 16 5.3. Refrigerant Type and Charge Size

................................ ................................ ............................. 16 5.4. Typical Leak Rates and Direct Emissions

................................ ................................ ................. 17 5.5. En ergy Consumption

................................ ................................ ................................ .................. 18 5.6. Capital and Installation Costs

................................ ................................ ................................ ..... 18 6. Low

- Charge Multiplex Systems

................................ ................................ ................................ ...... 18 6.1. Description

................................ ................................ ................................ ................................ . 18 6.2. Penetration of Technology

................................ ................................ ................................ ......... 20 6.3. Refrigerant Type and Charge Size

................................ ................................ ............................. 20 6.4. Typical Leak Rate and Direct Emissions

................................ ................................ ................... 20 6.5. Energy Consumption

................................ ................................ ................................ .................. 21 6.6. Capital and Installation Costs

................................ ................................ ................................ ..... 21 7. Advanced Self

- Contained Systems

................................ ................................ ................................ .. 21 7.1. Description

................................ ................................ ................................ ................................ . 21 7.2. Penetration of Technology

................................ ................................ ................................ ......... 22 7.3. Refrigerant Type and Charge Size

................................ ................................ ............................. 22 7.4. Typical Leak Rate and Direct Emissions

................................ ................................ ................... 22 7.5. Energy Consumption

................................ ................................ ................................ .................. 22 7.6. Capital and Installation Costs

................................ ................................ ................................ ..... 23 8. Total Equivalent Warming Impact (TEWI)

................................ ................................ ................... 23 8.1. TEWI Comparisons

................................ ................................ ................................ .................... 23 9. Retrofitting R

- 22 S upermarket Equipment

................................ ................................ ................... 28 9.1. System Efficiency

................................ ................................ ................................ ...................... 28 9.2. Retrofit Cost

................................ ................................ ................................ ............................... 29 9.3. Retrofit Procedures

................................ ................................ ................................ .................... 29 10. References

................................ ................................ ................................ ................................ .......... 30 Appendix A: Best Practices for Retrofitting R

- 22 Equipment

................................ .............................. 333



## 1. Executive Summary

This report presents a wide range of data collected on five types of supermarket refrigeration systems: direct expansion, secondary loops, distributed, low

- charge multiplex, and advanced sel f

- contained systems. In many cases, varying or even conflicting information was obtained from the published literature and/or industry experts. Table ES

- 1 , below, summarizes the results of this data analysis

.
Table ES

- 1

. Summary of Key Attributes of Supermarket Systems

, Based on ICF Analysis Baseline Alternative Technologies Direct Expansion (DX) Secondary Loop Distributed Low

- Charge Multiplex Advanced Self

Contained Estimated Penetration of Techn ology in to New / Remodeled U.S. Supermarkets 60% to 80% (

~ 70%) 3% to 5%

(

~ 4%) 18% to 35%

(

~ 26%) Minimal M inimal

Common Refrigerants R

- 22, R

- 502, R

404A, R

- 507A R

- 404A, R

- 507A R

- 22, R

- 404A, R

507A R

- 404A, R

- 507A R

- 134a, R

- 404A, R

- 507A Average Leak Rates D uring Use 15% to 35%

(Old systems: 25%; New systems: 15%) < 2% to 15%

(Literature: <2% to 5%; Industry: 10% to 15% ) 5% to 25% 25% Literature: 1%; Industry: 10%

Comparison of Alternatives to Baseline (DX) Typical Charge Size 10% to 50% 12% to 60% 30% t o 60% 5% to 10%

Change in Direct Emission Reduction - 44% to

- 99% (HFCs);

- 100% ( a mmonia, HCs

) - 75% to

- 95% NA NA

Change in Energy Consumption - 5% to + 15%; 0% to + 20% -

8% to + 16%; 0% to + 10% - 12 % +7

%

Change in Capital Cost +10% to + 25% (capit al costs are on the higher end of this range for systems using natural refrigerants) 0% to + 33% 0% 0%

Change in Installation Cost - 4% to +10%

- 25% to +15% 0% 0% to + 15%

TEWI Reduction 42% to 61% 38% to

60% 24% to

44% 56% NA = Not a vailable

.4



## 2. Introduc tion

Supermarkets are defined as retail food stores with sales greater than $2 million. In 2004, t he Chain Store Guide estimated that there were over 31,000 supermarkets in the United States. The top 20 supermarket chains, with 18,276 stores , hold 77 % of total retail groceries sales in the U.S (Chain Store Guide

, 2004).

Published e stimates of the average supermarket size in the United States vary widely. UNEP (2003 ) estimate d that the average supermarket in the United States is 43,000 ft 2 ; m ore recent industry estimates
concur, indicat ing that the average store size is currently about 45,000 ft 2

. However, a 2002 study by Arthur D. Little (ADL) estimated that newly constructed supermarkets in the United States are 60,000 ft 2

, and this will be the averag e size of all supermarkets in 8 to 10 years.

Annual energy use in supermarkets ranges from 100,000 kWh/year to 1.5 million kWh/year , depending on store size. Refrigeration energy consumption in a typical supermarket is estimated to comprise 30% to 50% o f total energy consumption , or up to 65% for small supermarkets (ADL, 2002 ; Baxter and Walker, 2003 ; IPCC/TEAP , 2005). According to IEA (2003), c ompressors and condensers account for 60% to 70% of refrigeration energy consumption , while d isplay and storag e cooler fans, display case lighting, evaporator defrosting, and anti

- sweat heaters account for the remainder (IEA, 2003).

Figure 1 , below, presents the typical layout of a supermarket with the refrigerated display cases and
sto rage areas located around the store’s perimeter.

Figure 1 . Typical Supermarket Layout

Source: ADL

(1996)

. Approximately 4,000 new supermarket refrigeration systems are purchased each year, with about 60 % being for new store appl ications and 40 % for remodels (Humphrey, 2000)

. One industry expert estimated that of his company’s sales of DX systems, 70% of sales are for new store applications, while 30% are for remodels. D epending on the supermarket chain , supermarket remodeling o ccurs every seven to ten years (Humphrey

, 2000) , although the life span of refrigeration equipment is estimated to be between 10 and 20 years ( IPCC/TEAP , 2005 ) . The trends for new supermarket construction and remodeling in the United States over the last several years are presented in Figure 2 , below.5

Figure 2 . U.S. Trends for New Supermarket Stores and Remodels



### 600 800 1000 1200 1400 1600 1800 2000 2200

2001 2002 2003 2004 (proje cted) YearNumber of Stores



### Remodels Openings

Source: Chain Store Guide ( 2001, 2002, 2003, 2004

)

. Currently, nearly all supermarket refrig eration equipment in use contains either HCFCs (R

- 22) or HFCs (R

- 404A and R

- 507A ). The estimated market breakout by refrigerant type, as provided by two U.S. industry sources, is presented in Figure 3

. Figure 3 . Estimated Breakout of In

- Use Supermarket Equipment, By Refrigerant Type

Percent of In

- Use Equipment Refrigerant Manufacturer A Manufacturer B CFCs 5% 0% HCFC

- 22 65% 40% HFCs a 30% 60%

a Includes R

- 404A and R

- 507A

. According to industry estim ates, R

- 404a is used in a larger portion of systems than R

- 507A

. There are many types of refrigeration systems in use in U.S. supermarkets, many of which are customized to fit particular stores’ needs. These systems vary in many aspects, including store layout, refrigerant type, and refrigerant charge size.

T his paper describe s the most common, conventional type of supermarket refrigeration systems in use

— the direct expansion (DX) system

— as well as four alternative technologies that are still being impr oved upon and

, increasingly

, penetrating the U.S. market . These systems provide the potential to reduce consumption and emissions of ozone depleting substance (ODS) or greenhouse gases (GHGs) and , in
some cases, energy consumption . These four technologie s include:

• Secondary loop systems;

• Distributed systems;

• Low

- charge multiplex systems; and

• Advanced self

- contained systems.6

These systems are often able to operate with a lower refrigerant charge and non

- ODS refrigerants . Other innovations in these syste ms, described in later sections of this paper, can also help to reduce refrigerant emissions.

The remainder of this report is structured as follows :

• Section 3 discusses traditional DX systems ;

• Section 4 details secondary loop systems;

• Section 5 provides information on distributed systems;

• Section 6 presents information on low

- charge multiplex systems;

• Section 7 di scusses advanced self

- contained systems ;

• Section 8 presents a TEWI analysis, comparing the direct and indirect warming impacts of each of the supermarket systems for which quantita tive data is available;

• Section 9 presents the information on efficiency and cost penalties associated with R

- 22 supermarket retrofits;

• Section 10 provides the references used in this repor t; and

• Appendix A provides best practices for perform ing R

- 22 retrofits.

In each of the technology discussions (Section 3 through 7 ), brief system descriptions are provided, as are

e stimates of the system s ’ market pene tration s in the United States, common refrigerant s , typical charge size s and leak rate s, direct emissions

, energy consumption , and capital and installation costs.7



## 3. Direct Expansion (DX) Systems

3.1. Descript io n
In a direct expansion ( DX ) system, t he compress ors are mounted together and share suction and discharge refrigeration lines that run throughout the store feeding cases and coolers. The compressors and condensers are located in a separate machine room

, either in the back of the store or on its roof

, to reduce noise and regulate heat rejection. These multiple compressor racks operate at various suction pressures to support display cases operating at different temperatures (Baxter and Walker

, 2003 ; Powell

, 2003 )

. The hot gas from the compressors is piped to the condenser and converted to liquid. The liquid refrigerant is then piped to the receiver and distributed to the cases and coolers by the liquid manifold. After cycling through the cases, the refrigerant returns to the suction manifold and the comp ressors ( Southern California Edison and Foster

- Miller, Inc., 2004). Figure 4 , below, presents the layout of a typical DX system in a supermarket

. Figure 4

. Direct E xpansion

(DX) R efrigeration S ystem

S ource: IEA

( 2003 ).

3.2. Penetration of Technology DX systems have traditionally been the most commonly used commercial refrigeration systems in the U nited S tates

. I n 2002, Powell estimated that DX systems were installed in 90% of supermarkets (Powell, 2002)

. In 2005, o ne equipment manufacturer estimated that 79% of new commercial refrigeration systems sold by his company are DX systems
, while a n other manufacturer provided a lower estimate of 60%

. Thus, DX systems represent an estimated 60% to 80% of new mark et sales in the United States

.8

3.3. Refrigerant Type and Charge Size

R

- 22 has been the most commonly used refrigerant in DX systems

, with R

- 502 often used for low

temperature applications . However
, R

- 404A and R

- 507A are increasingly p enetrating the U.S. market as an alternative for both R

- 22 and R

- 502 ( IPCC/TEAP , 2005 ; Powell, 2001 ; Powell, 2002 ). As shown in Figure 5

, U.S. equipment manufacturers provided varying estimates of the breakout of refrigerant types that are used in DX syst ems sold today

. Figure 5

. Estimated Breakout of Refrigerant Types Used in New DX Systems Sold Today

a Refrigerant Source HCFC

- 22 HFC

- 404A HFC

- 507A Manufacturer A 10% 60% 30% Manufacturer B 33% 33% 33% b Manufacturer C 50% 50% 0%

a These estimates are provided for each individual manufacturer, not for the U.S. market as a whole.

b Use of R

- 507A is reportedly increasing the fastest.

Charge size depends not only on store size, but also on the specific equipment and applications used (e.g., number of racks, low/medium/high temperature applications), which varies from store to store. Estimated charge sizes of DX systems, based on published literature and industry information obtained for this report, are shown in Figure 6

. Figure 6 . Estimated Charge of DX Systems As a Percent of Floor Area Store

Size (ft 2 ) Charge

Size of

a DX System (lbs) Comments Source

4% 45,000 2,000 Using only medium

- temperature equipment Manufacturer A 6 % 60,000 3,600 ADL (2002) 6%

- 7% 45,000 2,866 to 3,086 Manufacturer C 7.5%

- 10% 60,000 4,500 to 6,000 Using 3 racks Manufacturer B

8%

- 14% 35,000 3,000 to 5,000 Southern California Edison and Foster

- Miller, Inc. (2004)

According to the above sou rces , DX charge size s can range between 4% and 14% of supermarket square footage.

3.4. Typical Leak Rates and Direct Emissions Figure 7 , below, presents estimated leak rates provided in published literature and by industry sources

co ntacted for this report

. As shown, leak rates can vary widely; the reduction in leakage from DX systems can be explained by a number of steps taken by equipment manufacturers and users to minimize leakage, including: designing the system for tightness, pr acticing maintenance procedures for early detection and leakage repairs; training personnel; and recovering refrigerant at end

- of

- life (IPCC/TEAP, 2005).9

Figure 7 . Estimated Annual Leak Rates of DX Systems Annual Leak Rate s Comm ents Source

5% to 10% Based on two studies performed in Germany Birndt et al. (2000), Haaf and Heinbokel (2002) 3%

- 22% (18% average ) Based on a sample of 1,700 supermarket systems in the U.S. and several European countries IPCC/TEAP (2005)

12.4% Base

d on a field test Southern California Edison and Foster

- Miller, Inc

. (2004) 15% Newer equipment IEA (2003)

15%

- 35% M

ultiple factors for such a high leak rate were cited

, including poor installation and maintenance Manufacturer B

20%

- 35% Bivens and Gage (2004)

25% After equipment has been in service for several

years Manufacturer A, Manufacturer B, Manufacturer C

> 30% Older equipment IEA (2003)

Estimates of annual leak rates for DX systems range from 3% to 35% for in

- use equipment, with the high er annual leak rates (25%) being more characteristic of older equipment and the lower ones (15%) being more characteristic of newer equipment.

3.5. Energy Consumption DX systems consume significant amounts of energy due to the long pipe runs between the displa y cases and compressor racks, which result in pressure drops and suction gas heating. In addition, compressor run times are increased, increasing compressor energy consumption (Southern California Edison and Foster

- Miller, Inc., 2004). However, DX system s have less thermal resistance, and no separate fluid pumping equipment, giving them an efficiency and cost advantage compared to alternative systems ( IPCC/TEAP , 2005). According to ADL (2002), a typical DX system in a 60,000 ft 2 supermarket is estimated to consume approximately 1.2 million kWh/year. According to an industry expert, a 45,000 ft 2 store wil l consume 1.45 million kWh/year

.

3.6. Capital and Installation Costs

One U.S. equipment manufacturer estimated that, for a store that is 60,000 ft 2

, where 3 racks are required, total capital cost is about $165,000 (i.e., $55,000 per rack). The cost of food cases would be in additional to this. According to another equipment manufacturer, the installation cost of a DX system in a 30,000 ft 2 store is approxim ately $130,000, or $4.33/ft 2 . In addition, the cost of DX systems will depend on the type of refrigerant used; currently

, the initial cost of an HFC DX system is estimated to be two to three times more than the cost of an R

- 22 system

. 

## 4. Secondary Loop Syste ms

4.1. Description

In s econdary loop systems , two liquids are used. The first is a cold fluid, often a brine solution, which is pumped throughout the store to remove heat from the display equipment. The second is a refrigerant that is isolated from the equip ment cooled and passes through a heat exchanger to be cooled (EPA

, 2004). Secondary loop systems can operate with two to four separate loops and chiller systems depending on the temperatures needed for the display cases. Secondary loop systems may use ei ther reciprocating or screw compressors , although high

- efficiency screw compressors have greater energy savings potential (Southern California Edison and Foster

- Miller, Inc., 2004)

.10

The two main disadvantages associated with secondary loop system s are a l oss of energy efficiency and higher capital costs ( EPA, 2004 ; IEA, 2003 )

. One benefit to secondary loop systems is that they have improved temperature control compared to conventional direct expansion systems . This is an important advantage in the United States

, which has recently tightened its regulations on temperature control for refrigerated products such as meat, poultry, and fish ( EPA, 2004 ; IEA, 200 3 )

. Figure 8 presents a diagram of a secondary loop refrigeration system.

Figure 8

. Secondary Loop Refrigeration System

Source: Southern California Edison and Foster

- Miller, Inc. (

2004 ).

4.2. Penetration of Technology

One U.S. equipment manufacturer estimated that a pproximately 5% of its new supermarket sale s are secondary loop systems. 1 Another manufacturer estimated that sales of secondary loop systems represent only about 3% of its new supermarket sales

. Based on this data

, the total market penetration of secondary loop systems into new or remodeled stores is estimated to range from 3% to 5% in the United States

.

4.3. Refrigerant Type and Charge Size According to U.S. equipment manufacturers interviewed for this report, s econdary loop systems use primarily R

- 404A (about two

- thirds) and R

- 507A (about one

- t hird)

. No secondary loop systems are known to have been sold with R

- 22 or ammonia within the Unite d States.

1 Supporting this estimate, one supermarket chain in the U.S. reported that 5% of its systems a re secondary loop systems (Godwin, 2005).11

In Europe, however, ammonia secondary loop systems are in use. In addition, CO 2 has also been gaining market share as a secondary coolant (IPCC/TE AP, 2005) . Although one industry expert noted that CO 2 has lots of potential for use in low

- temperature applications, currently, safety issues prevent the widespread use of CO 2 in the United States (Beeton, 2005).

Because the primary refrigerant does not need to circulate throughout the store, secondary loop systems can operate with a significantly lower refrigerant charge than DX systems. Thus, t he charge size of a secondary loop system is estimated to be 10 % to 25% of the charge in a DX system (ADL

, 20 02 ; Bivens and Gage, 2004 ; IPCC/TEAP , 200 5 ; IEA, 2003 ) while other estimates range from 30% to 50% of the charge size of a DX system (Godwin, 2005; Southern California Edison and Foster

- Miller, Inc., 2004)

. Figure 9 , below, pre s ents a summary of the estimated charge size estimates for secondary loop systems provided by various source s

. Variations in charge size estimates are likely associated with differences in secondary loop equipment and, potentially, different baseline compa risons (i.e., differences in the size of “conventional” DX systems).

Figure 9 : Charge Size of a Secondary Loop System as a Percentage of the Charge Size of a DX System Charge Size

as a Percentage of DX Systems Store

Size (ft 2 ) Actu al Charge Size (lbs) Comments Source

1%

- 1.5% 35,000 300 to 500 Based on theoretical calculations made in preparation

for field study. Field study required additional charge to provide heat reclaim for hot water and space heat. Southern California Ediso n and Foster

- Miller, Inc. (2004)

10%

- 15% NA NA IEA (2003) 11% 60,000 396 ADL (2002)

15%

- 25% NA NA Based on a sample of 1,700 supermarket systems in the U.S. and several European countries IPCC/TEAP (2005)

30%

- 40% NA NA Based on a case study of a chain store in North America Godwin (2005)

40% a 45,000 1

, 200 Manufacturer A

~50% 42,000 1,400 Based on a case study of a supermarket in California Southern California Edison and Foster

- Miller, Inc. (2004) NA=Not Available

a Medium temperature only

.
B ased on the data presented above

, although theoretical calculations indicate that secondary loop systems could require a charge of as little as 1% of DX systems, according to several case studies, secondary loop systems actually require a charge of between 10% and 50% of DX systems.

4.4. Typical Leak Rates and Direct Emissions Secondary loop systems have lower annual leak rates than DX systems because they have a reduced number of connecting joints where leaks can occur (Bivens and Gage, 2004 ; EPA, 2004)

. In a ddition, secondary loop systems use pre

- manufactured pipes that are often ma de of plastic instead of copper; therefore, they do not require braz ing (EPA, 2004). Estimates of annual leak rates for secondary loop systems ranged from less than 2% to 15% , as presented by Figure 10

. Based on the more recent data available from U.S. systems, this range may be closer to 10% to 15% in the United States

.12

Figure 10 . Estimated Annual Leak Rates of Se condary Loop Systems
Annual Leak Rate Comments Source
U.S. D ata 2%

- 5% ADL (2002) 5% IPCC/TEAP (2005) 10% Manufacturer A

12% This system uses glycol (ethylene or propylene) as

cooling fluid to remove heat from food products in

cases. Manufacturer B

14.8% Southern California Edison and Foster

Miller, Inc. (2004)
International D ata < 2% Based on a study of supermarkets in Sweden. Engsten and Lindh (2004)

The combination of these reduced leak rates and the lower charge sizes results in significa nt direct emission reductions (Bivens and Gage, 2004; EPA, 2004). Indeed, secondary loop systems are estimated to experience total direct emissions reductions of 44 % to 99% relative to DX systems (see Figure 11 ).

Figure 11

. Estimated Direct Emissions of Secondary Loop Systems Relative to DX Systems Direct Emissions Relative to DX Systems Comments Source

- 44% This estimate is based on a comparison field study of a secondary

loop system wit

h an annual leak rate of 14.8% (compared to 12.4% for DX), and a charge size equal to 11% of a DX system

. Southern California Edison and

Foster

- Miller, Inc. (2004)

- 50% to

- 90% Based on a sample of 1,700 supermarket systems in the U.S. and

several Europ

ean countries IPCC/TEAP (2005)

- 75% Godwin (2005)

- 98.5% Assumes a 2% to 5% reduction in annual leak rate (compared to 15% for DX) and that the charge size is equal to 11% of a DX system

. ADL (2002)

4.5. Energy Consumption

Most studies have found that se condary loop systems require more energy than conventional DX systems. Reasons for increased energy use include (Southern California Edison and Foster

- Miller, Inc., 2004):

• The use of display cases containing evaporators designed for DX systems. The evapor ator coils have heat transfer characteristics that are not appropriate for use with a secondary fluid.

• Operation of the refrigeration system reducing the efficiency of the refrigeration compressors.

• The viscosity of the glycol

- water mixture used in many se condary loop systems

, which is much higher than that of water alone, increasing the fluid friction and pumping power. Estimates of the energy consumption of secondary loop systems relative to DX systems are shown in Fig ure 12

.13

Fig ure 12 . Estimated Energy Consumption of Secondary Loop Systems Relative to DX Systems Energy Consumption Relative to DX System Store Size (ft 2 ) Comments Source

0% to + 20% NA Estimates are for secondary loop systems with ammonia, hydrocarbons, or HFCs Estimate is b

ased on a sample of 1,700 supermarket systems in the U.S. and several European countries IPCC/TEAP (2005)

+5% to + 20% NA D ata reported from 77 supermarkets with secondary loop systems in Germany Haaf and Heinbokel (2002 )

+10% to + 15% NA UNEP (2003) +15% to + 20% 45,000 Manufacturer B +17% 60,000 ADL (2002) NA = Not Available

Based on this data, average secondary loop systems in use consume 0 % to 20% more energy than DX systems.

However, e nergy savings are possibl e with advanced secondary loop systems. For example, t he following design features can lead to energy savings:

• C lose coupling between the chiller evaporator and the compressor suction to reduce pressure drop and refrigerant gas overheating ( Southern Cali fornia Edison and Foster

- Miller, Inc., 2004 ) ;

• I mproved pump capacity control and use of a low viscosity secondary fluid to reduce the energy use involved in circulating the secondary fluid ( Southern California Edison and Foster

- Miller, Inc., 2004 ) ;

• D esign of display cases and fixtures for secondary loop systems to reduce heat transfer penalties ( Southern California Edison and Foster

- Miller, Inc., 2004 ) ;

• S ubcool ing of

the primary refrigerant with the secondary fluid and then use of the secondary fluid to de frost the heat exchangers in display cases (IEA, 2003).

• More efficient defrost (IPCC/TEAP, 2005);

• Better part load characteristics (IPCC/TEAP, 2005);

• Improved expansion device performance (IPCC/TEAP, 2005); and

• Use of high

- efficiency evaporative condensers (IEA, 2003).

Using these improved design features, secondary loop systems can lead to energy savings of 5% to more than 15% compared to DX systems , as presented by Figure 13

.14

Figure 13 . Es timated Energy Consumption of Advanced Secondary Loop Systems Relative to DX Systems Energy Consumption Relative to DX Systems Store Size (ft 2 ) Comments Source

- 4.9% 42,000 Achieved in a field test of an advanced secondary loop system Southern California Edison and Foster

- Miller, Inc. (2004)

- 10% 40,000 Compared to a DX system with an air

- cooled condenser; Baxter (2003)

>

- 14.9% 42,000 Energy Prediction made by Southern California Edison and Foster

- Miller, Inc., 2004 Southern California Edison and

Fost er

- Miller, Inc. (2004)

4.6. Capital and Installation Costs Capital and installation costs of secondary loop systems vary widely depending on the types of primary and secondary refrigerants used , as shown in Figure 14

. Figure 14 . Estimated One

-

Time Costs of Secondary Loop Systems using HFC Refrigerants

Relative to DX Systems Type of Cost Cost

Relative to DX System Primary

Refrigerant Secondary

Refrigerant Comments S ource

HFC Secondary Loop

Systems

+1 0% NA NA Based on a study of one supermarket chain in North America Godwin (2005)

+10% to +25% HFCs Based on a sample of 1,700 supermarket systems in the U.S. and several European countries IPCC/TEAP (2005) Capital

+17.5% HFC Not specified (secondary coolant or brine) EPA (2004)

+ 6.8% R

- 404A Glycol Rohrbach (2005) +15% a NA NA UNEP (2003) +15% R

- 404A or

R

- 507A Propylene glycol

or potassium formate brines IEA (2003) Capital and I nstallation

+15% to

+35% b NA NA Based on a study of 77 supermarket

s in Germany Bivens and

Gage (2004) +10% NA NA Godwin (2005) Installation

- 4% NA NA Manufacturer A

- 20% R

- 404A Glycol Rohrbach (2005) Maintenance

- 40% to

+50% NA NA Godwin (2005)

Secondary Loop

System s Using Natural Refrigerants Capital +25% A mmonia NA EPA (2004) Capital c +30% Hydrocarbons NA Based on a sample of 1,700 supermarket systems in the U.S. and several European countries IPCC/TEAP (2005)

NA = Not Available

. a This cost refers to the “initial cost

, ” which this analysis assumes to include both capital and installation costs

. b This cost refers to the “installed costs

, ” which this analysis assumes to include both capital and installation costs.

c This cost is assumed to be a capital cost, though the literature is not clear.

The highe r capital and/or installation costs associated with secondary loops can be offset by l ower operating and maintenance costs due to decreased charge sizes, decreased leak rates, faster defrost, lower15

maintenance needs, and longer shelf lives, potentially res ulting in significant cost

- savings over time ( EPA, 2004 ; IEA, 2003 ; Southern California Edison and Foster

- Miller, Inc., 2004 ).

Figure 15 , below, compares the maintenance costs associated with repairs to five DX and five secondar y loop systems in a major Midwest supermarket chain from April 2002 to April 2004. Overall, the secondary loop systems showed a decrease in the costs of labor, parts, refrigerant, and maintenance relative to the costs for DX systems. The secondary loop s ystems did, however, show a 20% increase in the cost of energy. 2

Figure 15

. Comparison of the Costs Associated with Repairs to DX and Secondary Loop Systems in a Major Supermarket Chain (

April 2002

– April 2004

) Store # Labor

($) Parts

($) Refrigerant

($) Refrigerant

(lbs) Secondary

Fluid ($) Secondary

Fluid (gal) Energy

($) Maintenance

($) DX Systems (5 S tores) # 1014 16,490 14,080 948 834 322,232 32,352 # 1067 17,336 19,236 3,360 4,420 383,729 44,352 # 1162 17,420 6,703 1,5 96 1,275 519,326 26,994 # 3039 13,060 5,107 1,968 1,765 432,620 21,900 # 4075 18,231 12,534 996 1,410 414,224 33,171 TOTAL 82

, 53 7 57

, 659 8

, 868 9

, 704 2

, 072

, 131 158

, 768 Secondary Loop Systems (5 Stores) # 12 19,048 3,814 1,200 200 545 47 515,804 24 ,854 # 1149 17,539 12,271 0 0 9,143 610 503,710 39,562 # 1150 10,250 5,600 2,100 350 0 0 524,280 18,299 # 1693 19,252 5,503 750 125 417 30 462,358 26,077 # 3159 14,878 12,742 2,550 425 321 40 492,175 30,956 TOTAL 80

, 966 39

, 92 9 6

, 600 1

, 100 10

, 42 6 727 2

, 498

, 327 139

, 747 Change R elative to DX - 1.9%

- 30.8%

- 25.6%

- 88.7% + 20.6%

- 12.0%

The total cost to purchase and install secondary loop equipment can range from 6.8% to 35% more than DX systems. Capital costs alone can range from 10% to 25% more tha n DX systems , with capital costs for systems using natural refrigerants (e.g., ammonia, hydrocarbons) being slightly higher than for HFC systems. In addition, e stimates of installation costs range from 4% less to 10% more than DX systems (for both HFC and natural refrigerants) . These increased one

- time costs can be offset by lower annual costs; maintenance costs associated with secondary loops is 20% to 50% less than DX systems

. 

## 5. Distributed Systems

5.1. Description Unlike DX systems , which have a central refr igeration room containing multiple compressor racks

, d istributed systems use multiple smaller rooftop units that connect to cases and coolers, using considerably less piping (Powell

, 2003 ; Baxter and Walker

, 2003). The compressors in a distributed system are located throughout the store near the display cases they serve. Thus, d istributed systems typically use scroll compressors

, which have lower noise and vibration levels than other compressors.

2 Because all the supermarkets used in the study are in the same geographical region, this analysis assumes that per unit costs of labor, parts, refrigerant, and energy are equal. However, data is currently unavai lable on the size of each of these supermarkets, which could undermine the comparability of these data.16

The compressors are connected by a water loop to the cooli ng units on the roof or outside of the store (EPA

, 2004). Figure 16 presents the layout of a distributed system.

Figure 16

. Distributed System

Layout

Source: IEA

( 2003 )

5.2. Penetration of Te chnology UNEP (2003) noted that, although distributed system s had been developed about 5 years prior

, they still did not constitute a significant share of the global market

. However, recent information indicates that distributed systems are gaining a n imp ortant share in the U nited S tates ’ market. Indeed, according to two U.S. equipment manufacturers , distributed systems account for 18% of one company’s sales and 35% of the other ’ s sales

. Thus market penetration of distributed systems is estimated to rang e from 18% to 35%.

5.3. Refrigerant Type and Charge Size Distributed systems use R

- 22, R

- 404A and R

- 507A (ADL

, 2002 ; IPCC/TEAP

, 200 5 )

. Figure 17 presents estimated market percentages of each refrigerant used in distributed systems

, a s estimated by two U.S. equipment manufacturers.17

Figure 17 . Estimated Breakout of Refrigerant Types Used in New Distributed Systems Sold Today

a Refrigerant HCFC

- 22 HFC

- 404A HFC

- 507A Manufacturer B 0% 75% 25% Manufacturer A 10% 60% 30%

a E stimates shown are for individual manufacturer s , not for the U.S. market as a whole.
Because distributed systems require less piping than DX systems, less refrigerant is needed (Powell, 2003; Baxter and Walker, 2003). E stimates of the charge size of distributed systems range from 12% to 60% of conventional DX systems , as presented in Figure 18

. Figure 18 . Estimated Charge Size of Distributed Systems as a Percentage of DX Sys tems Charge Size

a s a Percent age of DX System

s Store Size (ft 2 ) Estimated Charge Size (lbs) Comments Source

12% 60,000 600 Using water

- cooled condensers Manufacturer B 19% 60,000 960 U sing air

- cooled condensers Manufacturer B 25% 42,000 900 ADL (2002)

25% 35,000 300 to 500 Based on a sample of 1,700 supermarket systems in the U.S. and several European countries IPCC/TEAP (2005)

33% NA NA High

- efficiency scroll compressors are able to operate at lower condensing temperatures than conventional recipro

cating compressors; tests performed by the Department of Energy’s Oak Ridge National Laboratory (ORNL) ACHR (1999)

30%

- 35% NA NA IEA (2003)

50%

- 60% NA NA Using separate rooftop condensers for each cabinet IEA (2003)

NA = Not Available

5.4. Typical Leak Rates and Direct Emissions

The use of

distributed systems in place of DX systems can potentially reduce ODS emissions because smaller refrigeration units are distributed among the refrigerated and frozen food display cases

. Through this set

- up, distribute d system s significantly reduce the refrigerant inventory and minimize the length of refrigerant tubing and the number of fittings that are installed in direct expansion systems, further reducing refrigerant leak age

.
Available data

indicate that annual le ak rates for distributed s ystems can range from 5% to 25% , as presented in Figure 19

. Figure 19 . Estimated Annual Leak Rate of Distributed Systems Annual Leak Rate Source <5% ADL (2002) 5%

- 7% IPCC/TEA P (2005) <8% Manufacturer B 25% Manufacturer A

When changes in both annual leakage and charge size are considered

, as well as emission reductions at end of life, e stimates of direct emission reductions associated with distributed systems can range from 75% to 90% compared to DX systems

. This lower bound estimate of 75% is based on the draft IPCC/TEAP report (2005), while the upper bound estimate of 90% is based on ADL (2002)

.18

5.5. Energy Consumption The amount of energy used by a distributed system depends on what type of compressor is installed in the system. Scroll compressors are generally less efficient at the evaporating and condensing temperatures needed in commercial refrigeration. However, scroll compressors, unlike reciprocating compressors, do

n ot have valves. Thus, they can operate at lower condensing temperatures, increasing their efficiency and reducing energy consumption (Powell, 2003 ; Baxter and Walker, 2003).

Literature sources disagree on the energy impact of distributed systems relativ e to DX systems. As presented in Figure 20

, distributed systems have been found to be more energy efficient (by about 8% to 16%) in some cases, but less efficient (by 0% to 10 % ) in others.

Figure 20 . Esti mated Energy Consumption of Distributed Systems Relative to DX Systems Energy Consumption Relative to DX Systems Source

- 8% ADL (2002) 10% to

- 16% ACHR (1999) 0% to +10% IPCC/TEAP (2005)

5.6. Capital and Installation Costs The capital cost s of distributed sys tems are estimated to be from 0 % to 33 % higher than DX system s , as shown in Figure 21

. Figure 21 . Estimated Capital Costs of Distributed Systems Relative to DX Systems Costs Relative to

DX Systems Comments Source
0% to + 10% Based on a sample of 1,700 supermarket systems

in the U.S. and several European countries IPCC/TEAP (2005)

+8% to + 10% Manufacturer B +33% EPA (2004)

The installation costs of distributed systems have been foun d to range significantly based on published literature and industry estimates. As shown in Figure 23 , installation costs have been found to be from 25 % lower

to 15% higher than DX systems.

Figure 22 . Estimated Installation Costs of Distributed Systems Relative to DX Systems Costs Relative to DX Systems Comments Source

+15% “Installed cost” a IEA (2003)

- 8% to + 10% Installation costs are less, primarily because less refrigerant

is needed. M anufacturer B

- 25% Less piping is required, resulting in reduced costs for

materials, time, and labor. Powell (2003)

a This analysis assumes that this cost include s both capital and installation costs.



## 6. Low

- Charge Multiplex Systems

6.1. Description

Low

- charge multiplex refrigeration systems can use several different control systems to reduce the amount of refrigerant charge needed and the amount of energy required to operate the system. In one type of control system, a control valve that operates a bypass from the condenser liquid line maintains a constant differential between the high and low pressures of the system. This limits the refrigerant charge to the amount needed to service all display case evaporators with no additional charge needed for the receive r , as presented in Figure 23 (Baxter and Walker, 2003 ; IEA, 2003 )

. A mixture of vapor and liquid19

refrigerant is sent to each display case lineup and storage room, controlled by the compressor rack. The evaporators are operated b y valves that control r efrigerant flow and evaporation (IEA, 2003). The refrigerant liquid bypassed by the valve is expanded and evaporated through heat exchange using the discharge manifold. This vapor is then piped to the suction manifold to be recompr essed and returne d to the compressor

(Baxter and Walker

, 2003)

. Figure 23 . Low

- Charge Multiplex System

Source: IEA (

2003 ).

In another type of control system, the refrigerant charge is reduced by minimizing the refrigerant contai ned in the receiver during operation (see Figure 24 ). The control valve and ambient temperature sensor act together to maintain a constant temperature difference between the condenser outlet liquid and the ambient

air. After the liquid refrigerant passes through the control valve, it is vaporized via heat exchange with the discharge manifold. The receiver stores any liquid refrigerant that is not vaporized (IEA, 2003).20

Figure 24

. Low

- Ch arge Multiplex System

Source: IEA

( 2003 ).

6.2. Penetration of Technology According to one U.S. equipment manufacturer , very few of these systems have been sold in the U.S., thus they comprise a negligible portion of new supermarket system sales

.

6.3. Refrigerant Type and Charge Size

One U.S. equipment manufacturer that produces low

- charge multiplex systems for the Canadian market, estimated that a ppr o ximately two

- thirds of the low

- charge multiplex systems it sells contain R

- 404A, while the remain ing third contain R

- 507A

. According to t his manufacturer

, only a few of these systems have been sold in the U.S.

Regarding charge size, available estimates suggest that low

- charge multiplex systems require only between 30% and 66% of that of DX systems, as shown in Figure 25

. Figure 25 . Estimated Charge Size of Low

- Charge Multiplex Systems Relative to DX Systems Charge Size as a Percentage of

DX Systems Comments Source

~30% In systems where charge is redu ced to the minimum amount needed by the evaporators IEA (2003)

66% In systems where the refrigerant inventory is minimized in the receiver Baxter (2003), IEA

(2003)

6.4. Typical Leak Rate and Direct Emissions According to one industry contact, l ow

- charge m ultiplex systems have a n annual leak rate of 25% , simil ar to that of DX systems

. No leak rate or direct emissions estimates for these systems were found in the literature reviewed

.21

6.5. Energy Consumption A field study performed by Oak Ridge National Laborator y (ORNL) e stimated that the low

- charge multiplex system used 11.6% less energy than the DX system (Baxter, 2003 )

. The control option that minimizes charge for the system evaporators is estimated to be as energy efficient as traditional DX systems. Moreov er, t he control option that minimizes refrigerant inventory in the receiver can produce some energy savings because the system compressors are able to operate at lower condensing temperatures than normal (IEA, 2003).

The use of a bypass control valve allow s compressors to operate at very low head pressures

, offering some energy

- saving potential. Because the condenser fans can consume all the compressor energy

sav ings in order to maintain the low head pressure, a “ fan control strategy ” is very important. V ariable

speed condenser fans are recommended to achieve the lowest fan energy consumption while maintaining the desired low head pressures (Baxter and Walker, 2003).

6.6. Capital and Installation Costs

Low

- charge multiplex systems using either control option are estimated to have the same installation costs as DX systems (IEA, 2003).



## 7. Advanced Self

- Contained Systems

7.1. Description Equipment considered to be self

- contained includes beverage vending machines, beverage merchandisers, beer coolers, undercounter refri gerators, refrigerators for commercial food service, ice machines, and drinking water coolers (ADL

, 2002). In advanced self

- contained refrigeration systems, the refrigeration compressors and water

- cooled condensers are located in the display cases. A gly col loop rejects heat from the display cases and carries it to the store’s exterior. The recent introduction of horizontal scroll compressors into the market (vertical scroll compressors were not suitable for use in display cases) permit more wide spread u se of self

- contained systems (Baxter and Walker

, 2003). Foam insulation is used in most equipment to keep temperatures inside the equipment low (ADL

, 2002). Figure 26 depicts the typical refrigeration circuit in a self

- contained unit.22

Figure 26 . Diagram of a Self

- Contained Refrigeration Circuit

Source: ADL

(1996)

.
7.2. Penetration of Technology Due to the high upfront costs associated with manufacturing self

- contained systems, there are currently very few su permarkets comprised entirely of self

- contained equipment in use in the United States

. One equipment manufacturer noted that his company has only produced a few of these systems

, and estimated that there were less than 10 in operation throughout th e entir e U nited States

. Therefore, U.S. p enetration of this technology is assumed to be minimal (<1%)

.

7.3. Refrigerant Type and Charge Size Although self

- contained equipment has historically contained R

- 22, today

, a dvanced self

- contained refrigeration systems used internationally typically use R

- 404 A and R

- 134a ( IPCC/TEAP , 2005 )

.
Total c harge size in a given supermarket could be as low as 5 % to 10 % of the charge size of a DX system

, if self

- contained systems are used for all refrigeration needs (IEA, 2003)

. For i ndividual types of equipment, c harge size can range from 0 .3 kg to several kilograms (ADL

, 2002).

7.4. Typical Leak Rate and Direct Emissions Refrigerant emissions in advanced self

- contained equipment are minimized by the use of brazed joints connecting the r efrigerant tubing and refrigeration system components (ADL, 2002)

. It is estimated that advanced self

- contained systems have a leak rate of approximately 1% (Baxter, 2003 ; Bivens and Gage, 200 4 )

. In addition, according to ADL (2002), because all the comp onents are in the same unit, there is a minimal amount of tubing, further reducing refrigerant emissions

. H owever, more recent information obtained from a U.S. industry contacts suggests that average in

- use leak rates of these systems are much higher

— abou t 10% annually

.

7.5. Energy Consumption

Much of the energy consumption of self

- contained equipment

is related to frequent door openings, large beverage cool down loads, and ice maker throughput. A study performed by ORNL indicated that23

advanced self

- containe d systems consume 7.3% more energy than do traditional DX systems (Baxter, 2003). S elf

- contained systems are often less energy efficient per kW of cooling power than centralized systems as they usually reject heat into the store, which then increase s the store’s demand for air

conditioning and, in turn, increases total energy costs ( IPCC/TEAP , 2005).

To reduce energy consumption of these systems , a study performed by ADL (2002) recommended the integrat ion of

heat reduction from individual units in a water circuit ( IPCC/TEAP , 2005). In addition, the following measures are suggested to improve system efficien cy (Baxter and Walker, 2003) :

• Maintain the capacity control of the compressor.

• Regulate t he condensing temperature to maintain a limited range

.

• E nsur e that the compressor capacity does not surpass the required refrigeration load to avoid excessive compressor cycling

.

• Ensur e a close link between the com pressor and the case evaporator to reduce the pressure drop at the co mpressor suction and limit the heat gain to the suction gas.

7.6. Capital and Installation Costs A study conducted by IEA (2003) estimates that a store that uses only self

- contained equipment is associated with approximately the same capital cost as a DX system, but with installation costs t hat are up to 15% higher

. In contrast, one U.S. industry representative claimed that there are “ very high ” upfront costs associated with self

- contained system s, although no quantitative estimates were provided

. 

## 8. T otal E quivalent W arming I mpact (TEWI)

The u se of supermarket refrigeration equipment generates “indirect” emissions of greenhouse gases (primarily carbon dioxide) from the generation of power required to operate the equipment. These indirect emissions can significantly reduce

— if not, outweigh

— the direct emission savings that can result from some alternative technologies. Hence, energy efficiency has a major impact on the total greenhouse gas emissions of an application.

Total Equivalent Warming Impact (TEWI) measures the environmental impact of greenhouse gases resulting from operation, service and end

- of

- life disposal of the equipment. It combines the effects of both the direct emissions of refrigerants and the indirect emissions resulting from energy consumption by the burning of fossil fuels and the generation of electricity for cooling. The calculation of TEWI is based on the global warming potentials (GWPs), developed by the Intergovernmental Panel on Climate Change (IPCC), which use CO 2 as a reference gas (Sand et al

. , 1997).

8.1. TEWI Compar isons Eight TEWI studies have been reviewed and assessed for this report:

1. Arnemann, M., D. Gebhardt, and H. Kruse

. 1995. “Experiementelle Bewertung neuer Kältemittelgemische als Ersatz für R

- 22 und R

- 502 [Experimental assessment of new refrigerant mixes as substitutes for R

- 22 and R

- 502] .” D ie K älte

- und Klimatechnik

(2): 66. As cited in Kruse, Horst, 2000. “Refrigerant Use in Europe.” ASHRAE Journal

. 2. Sand, James R., Steven K. Fischer, and Van D. Baxter

. 1997. “Energy and Global Warming Impacts of HFC Refrigerants and Emerging Technologies.” U.S. Department of Energy and Alternative Fluorocarbons Environmental Acceptability Study.24

3. I nternational Energy Agency

. 2003. “IEA Annex 26: Advanced Supermarket Refrigeration/Heat Recovery Systems, Final Repo rt Volume 1

- Executive Summary.” Compiled by Van D. Baxter, Oak Ridge National Laboratory. April.

4. EPA

. 2004. “Analysis of Costs to Abate International Ozone

- Depleting Substance Substitute Emissions.” Office of Air and Radiation (6205J), EPA 430

- R

- 04

- 006

. June. [Note: this analysis is based on data from ADL (2002).]

5. Baxter, V an D

. 2003. “Advances in Supermarket Refrigeration Systems.” U.S. Department of Energy, Oak Ridge National Laboratory, Oak Ridge, TN.

6. Baxter, Van D. and David H. Walker

. 2002. “Fi eld Testing of an Advanced Low

- Charge Supermarket Refrigeration System.” Paper presented at the New Technologies in Commercial Refrigeration Conference, University of Illinois at Urbana

- Champaign, Urbana, IL

. 22

- 23 July.

7. Biven s, Donald and Cynthia Gage

. 2004. “Commercial Refrigeration Systems Emissions.” Paper Presented at the 15 th

Annual Earth Technology Forum, Washington, DC

. 13

- 15 April.

8. Intergovernmental Panel on Climate Change/Technology and Economic Assessment Panel

. 2005. Draft of IPCC/TEAP Speci al Report on Ozone and Climate, Chapter 4: Refrigeration.

These studies, each of which is discussed below, have demonstrated that, although indirect emissions can significantly reduce the net environmental benefit associated with alternative system s used in supermarket refrigeration , alternative systems still represent net greenhouse gas improvements over conventional DX systems.
The study conducted at the Research Centre for Refrigeration and Heat Pumps in Hanover, Germany using R

- 404A, R

- 407A, R

- 4 07B, R

- 407C, R

- 507A , R

- 410A, and R

- 290 (propane), determined that only R

- 410 and R

- 290 have an improved TEWI compared to R

- 22, with similar performance in terms of energy efficiency. The other refrigerants were shown to have a 5% to 15% higher energy cons umption. Figure 27 presents the results of this study (Arnemann et al., 1995, as cited in Kruse, 2000).

Figure 27 : TEWI Comparison of R

- 22 and its Substitutes

Source: Kruse

( 2000 ).

Figure 28 presents the results of a study conducted by Sand et al . (1997) (also discussed in the IEA (2003) report), comparing DX, secondary loop, and distributed systems, each with a variety of different refrigerants in North America , including ammonia ( R

- 717) in secondary loop systems . As shown, both secondary loop and distributed systems offer considerable TEWI reductions compared to the DX systems,25

especially when careful attention is paid to optimizing design and operational efficiency. The large refrigerant charge and high direct emission rate of DX systems result in high TEWI values, with direct refrigerant loss accounting for about half of the total emissions (IEA, 2003).

Figure 28 : TEW I Analysis of Low Temperature Supermarket Refrigeration Systems Reported by Sand et al. (1997)

Source: IEA

( 2003 ).

EPA (2004) includes a TEWI analysis comparing distributed, HFC secondary loop, and ammonia secondary loop systems to a conventional DX sys tem, based on data provided in ADL (2002). As shown in Figure 29 , all alternative systems were found to result in net emission savings compared to conventional DX systems, with the distributed option resulting in the lowest net emissions, due to its lower energy consumption (despite larger charge size and leak rate compared to the secondary loop systems).

Similar results for distributed and HFC secondary loop systems are reported by Baxter (2003) (as also cited in IEA (2003)). Baxter (2003) compared not only distributed and secondary loop systems, but also low

- charge multiplex and advanced self

- contained systems, all of which were tested in a Washington, DC location, assuming a 15

- year service life. As shown in Figure 30 , the analysis indicates that alternative systems can reduce net greenhouse gas emissions by 20% to more than 60% compared to the baseline DX system. Of all alternatives, secondary loop systems with evaporat ive condensers were found to achieve the greatest emission reduction , even when using fluorocarbon refrigerants. In addition, although self

contained system s have the smallest leak rates, their higher energy use leads to higher net emissions than secondar y loop and distributed systems. However, Baxter (2003) found that self

- contained systems could potentially achieve the same TEWI reductions as distributed systems, if more efficient, small compressors and/or other improved system components are developed t o help reduce system energy use. (Baxter, 2003)26

Figure 29 : TEWI Results for 60,000 ft 2 Supermarket

, as R eported in EPA (2004 ) and B ased on ADL (2002) Centralized Direct Expansion System (Base) Distributed

System Ammonia

Secon dary Loop System HFC Secondary

Loop System
Charge Size (kg) a (% change) 1,633 408 (

- 75 % ) 180

(

- 89 % ) 180

(

- 89 % ) HFC Leak Rate (% of charge/yr) a 15% 4% 0% 2% Direct Emissions (kg/yr) 245 16 0 4 Change in Direct Emissions (kg/yr) N/A (229) (245) (241) Change in Direct Emissions (TCE/yr) c N/A (204) (218) (214) Energy Consumption

-

kWh/ yr a (% change) 1,200,000 1,100,000 (

- 8 % ) 1,400, 000 d ( + 17 % ) 1,400, 000 d ( + 17 % ) Indirect Emissions (TCE/yr) e 198 182 231 231 Change in Indirect Emissions (TCE/yr) N/A (1 7) 33 33

Change in Indirect Emissions (TCE/yr) per ton of cooling capacity b N/A (0.02) 0.05 0.05

Change in Net Emissions (TCE/yr) N/A (221) (185) (181) Net Electricity Cost ($/yr) f N/A ($4,000) $8,000 $8,000 Note: Totals may not sum due to independent rounding. N/A = not applicable.

a Based on ADL (2002 ).

b Assumes that conventional direct expansion systems require 5 pounds (or 2.27 kg) of refrigerant per ton of cooling capacity ( EPA, 2004 ). For a 60,000 sq. ft. store using 3,600 lbs refrigerant (ADL, 2002), this translates to 720 tons of cooling capacity

c Assumes the refrigerant is R

- 404A (ADL, 2002).

d Recent technological advances on secondary loop refrigeration systems for supermarkets suggest that, with the use of improved technological features and design/manufacturing/contractor experience, these systems can lead to significant reductions in energy consumption (Baxter, 2003; EPA, 2004 ); however, these reductions are not assumed in this analysis.

e Assumes a national average emissions factor of 0 .606 kg CO 2 /kWh ( EPA , 2004).

f Assumes average energy costs for United States between 1994

- 1999 (of approximately $0.04/kWh) based on EPA (2004 ). Source: EPA (

2004 ).

Figure 30 : TEWI Analysis on Supermarket Refrigeration Conducted by Baxter (2003) Baseline ( DX ) Low

- Charge Multiplex Distributed Secondary Loop Advanced Self

Contained Condensing Type Air

- Cooled Evaporative Water

Cooled, Evaporative Evaporative Water

Cooled, Evaporative Water

- cooled, evaporative

Charge

- kg/kW (% c hange

) 4.15 2.77

(

- 33 % ) 1.24 (

- 70 % ) 0.69 (

- 83 % ) 0.27 (

- 93 % ) 0.14

(

- 97 % )

Primary Refrigerant R

- 404A/

R

- 22 a R404A/ R

- 22 a R

- 404A R

- 507A b R

- 507A

b R

- 404A

Leak Rate 30% 30% 15% 5% 10% 5% 5% 2% 1% Energy Use

kWh/year (% change

) 976,800 863,600

(

- 12 % ) 866

,100 (

- 11 % ) 875,200 (

- 10 % ) 959,700 (

- 2 % ) 1,048,300

( + 7 % )

TEWI Reduction c 24% 44% 59% 58% 61% 57% 58% 56%

a 1/3 R

- 404A (low temperature), GWP = 3260; 2/3 R

- 22 (medium temperature), GWP = 1700

. b R

- 507A , GWP = 3300

. c Relative to baseline.27

Baxter a nd Walker (2002) compared a distributed system using R

- 404A to a DX system using both R

- 22 and R

- 404A (for different racks), and determined that the distributed system achieved a TEWI reduction of 38% over the baseline DX system. In addition, the distribu ted system consumed 12% less energy than DX system.
Bivens and Gage (2004) found that distributed systems can lead to even greater TEWI reductions compared to DX systems

— achieving a 47% reduction. However, unlike previous studies, this analysis found tha t distributed systems consume the same amount of energy as DX systems

— not less . Bivens and Gage (2004) also compare secondary loop and low

- charge multiplex systems to DX systems, and conclude that secondary loop systems can achieve TEWI reductions of betw een 42% and 47%, and low

charge multiplex systems can achieve reductions of 46%.

Similar to Bivens and Gage (2004), the IPCC/TEAP draft report (2005) also reports that the energy consumption of distributed systems is equal to or greater than conventional D X systems. Figure 31 presents a comparison of the direct emission reductions, and energy usage of alternative supermarket refrigeration systems, as compared to the baseline DX system, as provided in the draft IPCC/ TEAP report.
Figure 31 : TEWI Data Reported in Draft IPCC/TEAP Report (2005) Baseline (DX) HFC Secondary

Loop Ammonia

Secondary Loop Distributed (HFC)

Refrigerant R

- 22 R

- 404A Ammonia R

- 404A Direct Emission Reduction 50% to 9 0% 100% 75%

Change in Energy Usage 0% to +20% 0% to + 20% 0% to +10%

TEWI Reduction Relative to DX 35% to 60%

Ad ditional data may be available in the near future; one manufacturer and a supermarket chain are conducting a study comparing the costs of DX an d secondary loop systems

. Another manufacturer is also developing a TEWI analysis and expects to have results av ailable in several months

.28



## 9. Retrofitting R

- 22 Supermarket Equipment

9.1. System Efficiency In addition to replacing ODS refrigeration equipm ent with alternative technologies, alternative refrigerants can also be used to retrofit or “convert” existing ODS (e.g., R

- 22) systems. However, many

ozone

- friendly substitutes for R

- 22 result in a reduction in cooling performance and energy efficiency,

w hich represents a major economic barrier to ODS alternatives. For example, Spletzer and Rolot t i (2004) conducted a performance study of R

- 22 retrofits converted to R

- 404A, R

- 407C, R

- 417A, and R

- 507A for use in medium

- temperature refrigeration loop , and fou nd that:

• R

- 417A produced the largest losses in refrigerating capacity of any of the retrofits

.
• R

- 407C produced a better capacity match and had the closest capacity of any of the alternatives at the 30oF box temperature condition. It also produced the highe st efficiencies of the retrofit refrigerants

.
• R

- 404A and R

- 507A performed similarly and produced the highest capacities, on average, of the retrofits.

Honeywell ( Gartland, 2005) also conducted a performance study of R

- 22 systems converted to R

- 404A, R

- 407 C, R

- 422A, and R

- 417A (medium

- temperature only). The study found that:

• All refrigerants showed efficiency loss at high am bient temperature in the medium

- temperature application.

• Only R

- 404A showed a capacity increase in the medium

- temperature application.

• All refrigerants showed a slight decrease in efficiency in the low

- temperature application.

• R

- 404A had the best capacity in the low

- temperature application.

The results of this study are summarized in Figure 32

. Figure 32 : Results of Performance Study of R

- 22 Systems Retrofitted with HFC Refrigerants, C onducted by Honeywell ( Gartland, 2005) R

- 404A R

- 507A R

- 407C R

- 417A R

- 422A Capacity (relative to R

- 22) Similar Similar Lower capacity at lower temperature

s Considerably lower capacity ~10% decrease at

low temperatures

Mass Flow (relative to R

- 22) ~45% higher ~45% higher 55% higher Temperature Glide Very low Very low 8

- 12°F 5

- 8°F 2

- 4°F

Pressure ~20% higher ~20% higher ~10% higher ~20% higher

Lubr icant Used Synthetic

lubricants Synthetic

lubricants Synthetic

lubricants Oil return issues

with mineral oil

use Reduced oil

return when used with mineral oil

Beeton (2005) noted that, while R

- 422A (One Shot® refrigerant) may be a viable alternative, R

- 4 04A is currently the most efficient retrofit refrigerant for R

- 22. O ne large supermarket chain (Bigg’s) has performed two retrofits, converting a low

- temperature rack and a medium

- temperature rack from R

- 22 to R

- 422A. The low

- temperature rack ran between 70% and 95% of capacity on R

- 22, and between 60% and 90% of capacity with extended periods below 50% of capacity after being retrofitted with R

- 422A. The medium

- temperature rack ran between 50% and 80% of capacity when using R

- 22 and consistently below 5 0% with R

- 422A. Due to the reduction in capacity, the number of compressors needed to29

maintain the suction pressure target is reduced, which in turn will lead to lower energy costs associated with compressor operation (ACHR News, 2005).

9.2. Retrofit Cost

Ac cording to one industry expert

, costs to retrofit R

- 22 retail food equipment to ODS alternatives can run very high:

• Retrofitting R

- 22 to R

- 407c/R

- 417a: $20,000

- $60,000

, depending on store size

• Retrofitting R

- 22 to R

- 404a/R

- 507A: $40,000

- $90,000

, dependi ng on store size (requires up to 200 expansion valve changes)

The above cost estimates were supported by one U.S. equipment manufacturer who estimates R

- 22 retrofit costs for a store of 30,000 ft 2 to be bet ween $50,000 and $70,000 . However, another U.S. equipment manufacturer estimated retrofit costs for a larger supermarket (between 60,000 ft 2 and 65,000 ft 2 ) to be above this range

— between $85,000 and $105,000

.

9.3. Retrofit Procedures Appendix A provides a checklist for conducting equipment retrofits.30



## 10. Refe rences

Air Conditioning, Heating & Refrigeration (ACHR) News. 2005. “Retrofitting R

- 22 supermarket systems.” Air Conditioning, Heating & Refrigeration News 226(1): 1 2

- 14 . 5 September.

Air Conditioning, Heating & Refrigeration (ACHR) News

. 1999. “D OE sponsors advanced supermarket refrigeration and hvac systems field air conditioning.” Air Conditioning, Heating & Refrigeration News 208(3): 13. 20 September.

Arnemann, M., D. Gebhardt, and H. Kruse, 1995. “Experiementelle Bewertung neuer Kältemittelgem

ische als Ersatz für R

- 22 und R

- 502 [Experimental assessment of new refrigerant mixes as substitutes for R

- 22 and R

- 502] .” D ie K älte

- und Klimatechnik

(2): 66. As cited in Kruse, Horst, 2000. “Refrigerant Use in Europe.” ASHRAE Journal . Available at http://www.usgbc.org/Docs/LEED_tsac/Energy/ASHRAE%20Journal%2009

- 00%20Refrigerant%20Use%20in%20Europe.pdf

. Arthur D. Little, Inc. (ADL ). 2002. “Global Comparative Analysis of HFC and Alternative Technologies for Refrigeration, Air Conditioning, Foam, Solvent, Aerosol Propellant, and Fire Protection Applications.” Final Report to the Alliance for Responsible Atmospheric Policy. Availa ble at http://www.arap.org/adlittle/HFCstudy3

- 22JD.pdf

. Arthur D. Little, Inc. (ADL). 1996. “Energy Savings Potential for Commercial Refrigeration Equipment.” Available at http://www.eere.energy.gov/buildings/info/documents/pdfs/comm_refridg_equip.pdf

Baxter, Van D. and David H. Walker

. 2003. “Analysis of advanced low

- charge refrigeration for supermarkets.” ASHRAE Transactions

. 1 January.

Baxter, Van D. and D avid H. Walker

. 2002. “Field Testing of an Advanced Low

- Charge Supermarket Refrigeration System.” Paper presented at the New Technologies in Commercial Refrigeration Conference, University of Illinois at Urbana

- Champaign, Urbana, IL

. 22

- 23 July.

Baxter , Van D. 2003 . “Advances in Supermarket Refrigeration Systems.” U.S. Department of Energy, Oak Ridge National Laboratory, Oak Ridge, TN.

Beeton, Warren. 2005. Copeland Refrigeration. “Future Trends in Refrigerants.” Presented at the 2005 F ood Market ing Institute Energy & Technical Services Conference, Montreal, Quebec. 18

- 21 September.
Birndt, R., Riedel, R., and J. Schenk. 2000. “Tightness of Commercial Refrigeration Systems.” DIE KALTE & Klimatchnik. September. As cited in Bivens, Donald and Cyn thia Gage. 2004. “Commercial Refrigeration Systems Emissions.” Paper Presented at the 15 th Annual Earth Technology Forum, Washington, DC. 13

- 15 April.

Bivens, Donald and Cynthia Gage

. 2004. “Commercial Refrigeration Systems Emissions.” Paper Presented at the 15 th

Annual Earth Technology Forum, Washington, DC

. 13

- 15 April.

Chain Store Gu ide

. 2004. Directory of Supermarket, Grocery & Convenience Store Chains.

Chain Store Gu ide. 2003 . Directory of Supermarket, Grocery & Convenience Store Chains.

Chain Stor e Gu ide. 2002 . Directory of Supermarket, Grocery & Convenience Store Chains.

Chain Store Gu ide. 2001 . Directory of Supermarket, Grocery & Convenience Store Chains.31

Engsten, Karolin and Jenny Lindh. 2004. “Refrigerant Management: The Issue of Minimizing Refrigerant Emissions

–a study of Swedish supermarkets.” Master’s Degree Project, Royal Institute of Technology, Sweden.

Gartland, Ted. 2005. Honeywell. “Replacing R

- 22 in Refrigeration.” Presented at the 2005 Food Marketing Institute Energy & Technic al Services Conference, Montreal, Quebec. 18

- 21 September.

Godwin, David. 2005. U.S. EPA. “Using Glycol as a Secondary Coolant.” Presented at the 2005 Food Marketing Institute Energy & Technical Services Conference , Montreal, Quebec. 18

- 21 September.

Haaf, S. and B. Heinbokel. 2002. “Alternative Refrigerants for Supermarket Refrigeration Installations.” Proceedings of DKV

- Tagungsbericht, 2(2). As cited in Bivens, Donald and Cynthia Gage. 2004. “Commercial Refrigeration Systems Emissions.” Paper Pr esented at the 15 th Annual Earth Technology Forum, Washington, DC. 13

- 15 April.

Humphrey, Joe

. 2000. “A Truly Super Market

. ” Engineering Systems

. May. Available at http://www.esmagazine.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2503,1519,00.ht ml

I nternational E nergy A gency (IEA). 2003. “IEA Annex 26: Advanced Supermarket Refrigeration/Heat Recovery Systems, Final Report Vol ume 1

— Executive Summary.” Compiled by Van D. Baxter, Oak Ridge National Laboratory. April.

I ntergovernmental P anel on C limate C hange /T echnology and E conomic A ssessment P anel (IPCC/TEAP). 2005. Draft of IPCC/TEAP Special Report on Ozone and Climate, Cha pter 4: Refrigeration.

Powell, Peter

. 2003. “Report charts supermarket trends.” Air Conditioning, Heating & Refrigeration News 220(1) : 9

- 10

. 1 September.

Powell, Peter

. 2002. “More ways to curb supermarket energy costs.” Air Conditioning, Heating & Refrigeration News 217(6): 16. 7 October.

Powell, Peter

. 2001. “Where refrigerants are, and where they’re going.” Air Conditioning, Heating & Refrigeration News 212(8): 1. 19 February.

Rohrbach, Mark. 2005. “Using Glycol as a Secondary Coolant.” P resented at the 2005 Food Marketing Institute Energy & Technical Services Conference, Montreal, Quebec. 18

- 21 September.

Sand, James R., Steven K. Fischer, and Van D. Baxter

. 1997. “Energy and Global Warming Impacts of HFC Refrigerants and Emerging Tech nologies.” U.S. Department of Energy Alternative Fluorocarbons Environmental Acceptability Study.

Southern California Edison and Foster

- Miller, Inc. 2004. “Investigation of Secondary Loop Supermarket Refrigeration Systems.” Report prepared for Californi a Energy Commission, Public Interest Energy Research Program. March.

Spletzer, Stephen and Gus Rolotti

. 2004. “Performance Study of R

- 22 Refrigeration Retrofits.” Paper Presented at the 15 th

Annual Earth Technology Forum, Washington, DC

. 13

- 15 April.

U nited N ations E nvironment P rogramme (UNEP). 2003. “2002 Report of the Refrigeration, Air Conditioning and Heat Pumps Technical Options Committee: 2002 Assessment.” UNEP , Nairobi, Kenya. January.32

U.S. Environmental Protection Agency ( EPA ). 2004. “Anal ysis of Costs to Abate International Ozone

Depleting Substance Substitute Emissions.” EPA Office of Air and Radiation (6205J), EPA 430

- R

- 04

- 006. June. Available at http://yosemite.epa.gov/oar/globalwarming.nsf/UniqueKeyLookup/RAMR62ASAF/$File/IMAC

All%20Chapters%206

- 24

- 04.pdf

.33



## Appendix A : Best Practices for Retrofitting R

- 22 Equipment

A. Checklist

This checklist is intended to be used before conducting a retrofit.

• Conduct preliminary leak check, with special attention to any mechanical joints, valves and fin surfaces. NOTE: REPAIR ALL LEAKS!

• Record baseline data on original system performance.

• Choose lubricant. NOTE: Because HFC refrigerants are not miscible or soluble with mineral oil compressor manufacturers require synthetic oils, such as Polyol Ester

- POE.

B. Procedure
The following steps should be followed when retrofitting a supermarket refrigeration system from R

- 22 to

an HFC refrigerant:

1. Isolate the R

- 22 refrigerant charge to the receiver.

2. Drain as much of the old lubricant from the system as possible, including from the

c ompressor sump, oil reservoir, and oil separator. If large amounts of mineral oil remain, it may clog the system and cause the efficiency of the heat exchangers to decline (Engsten and Lindh, 2003).

3. Replace oil filters and filter driers when performing oil changes.

4. Measure the amount of oil removed

, add back an identical quantity of new oil. NOTE: The

ne w oil chosen must be approved by the compressor manufacturer.

5. Run the system with R

- 22 for at leas t 24 hours. NOTE: S ystem s run ning for an extended period may require fewer oil changes.

6. Repeat steps 1 through 4 until t he residual oil is less than 5%, test ing using lab analysis or a refractometer.

7. Evaluate expansion devices using the process described below in Section C

.
8. Recover R

- 22 in the system.

9. Pull vacuum

.
10. Evaluate pressure controls, including high pressure cut

- outs, fan cycling controls, and pressure relief devices.

11. Recharge system with HFC refrigerant

.
12. Check system for leaks.

C. Valve Rebuilds (for systems built before 1995)

Systems built before 1995 will most likely require new gaskets and “o”

- rings (elastomers)34

1. Rebuild all Evaporator Pressure Regulators ( EPRs );

2. Rebuild all solenoid valves ;

3. Rebuild hold back valves ;

4. Rebuild heat reclaim valves ;

5. Evaluate TXVs and new refrigerant for proper capacity and superheat. Replace whole valve

or power head if necessary. NOTE: Exis ting R

- 22 valves may be under

- sized for higher mass flow refrigerants R

- 507A , R

- 404A and R

- 422A;

6. Replace "o"

- rings on the receiver float, and receiver optic switch ;

7. Replace nylon gasket on Roto Lock fittings . NOTE: Complete steps 6 and 7 prior to pulling

a vacuum.

D. System “Rack”

1. Replace schraeder caps and schraeder cores on high side. NOTE: A ll schraeder ca ps should be brass.

2. Replace liquid l ine filters on conversion date.

3. Replace suction felts or cores on conversion date

.
4. Use bra ss sealing caps on ball valves and compressor service valves

.
5. Set holdback va lves on the condenser drain leg.

6. Set EPRs to manufacturer ’s parameters before setting any superheats.

7. Set mechanical sub

- coolers to rack manufacturers ’ parameters. V erify stable operatio n before setting any superheats.

8. Set TXV superheats to 8o

- 1 0o for medium temperature applications and 5o

- 7o for low temperature applications. NOTE: With blended refrigerants use DEW values for superheat
measurements.

E. Tips
Keep the following items in mind when performing a retrofit:

• Perform the final oil change on conversion date ;

• Run a defrost cycle on all circuits prior to oil changes in order to aid oil removal;

• Replace oil separator filters on conversion date ;

• Dispose of used oil properly ;

• Recover R

- 22 and pull vacuum ;

• Complete all work outlined under rack system before recharging ;35 • Most HFCs have lower densities than R

- 22 so use proper charge amount; for example, when using R

- 404A, 87% of the size of the R

- 22 charge is required;

• All 400 series refrigerants must be liq uid charged ; and

• Always use proper personal protection equipment when handling refrigerants and oils.

R

- 404A requires a higher pressure and many of the systems components must be changed. The molecules of R

- 404A are also smaller than those of R

- 22, so the system must be much tighter to prevent leaks. In addition, t he POE oil that R

- 404A requires may eat through seals and membranes

, leading to higher leak rates.