1 

# Automatic Commercial Ice Maker Energy Conservation Standards – Energy Modeling Appliance Standards Department of Energy Building Technologies Program EERE
- 2010

- BT
- STD

- 0037 ACIM

- 2010

- STD

- 0037@ee.doe.gov June 19, 20142 

# Welcome

• Introductions (around the room )
• Role of the Facilitator
• Ground Rules

– Speak one at a time.

– Say your name for the record
– there will be a complete transcript of this meeting.

– Be concise
– share the “air

- time.”

– Keep the focus here
– cell phones on silent; limit sidebar conversations.

– Webinar participants turn phone on mute; “raise your hand” to be recognized to speak. 

# • Housekeeping Items
• Agenda Review
• Opening Remarks3 

# Agenda

• 9:00 – 9:20 am Welcome, Introductions

• 9:20 – 9:50 am Opening Remarks

• 9:50 – 10:45 am Background and Energy Model Overview

• 10:45 – 11:00 am Break

• 11:00 am – 12:15 pm Use of the Energy Model in DOE Analysis

• 12:15 – 1:15 p m Lunch

• 1:15 – 3:30 p m Energy Model Demonstration(s)

• 3:30 – 4:00 pm Next Steps and Closing Remarks4 

# Public Meeting Topics

1 Introduction and Opening Remarks 2 Background 3 Energy Model Description 4 Use of the Energy Model in DOE’s Engineering Analysis 5 Additional Energy Modeling 6 Discussion5 

# Listening Via the Webcast

• The Department is broadcasting this meeting live over the Internet.

• DOE is providing the webcast to accommodate stakeholders who are unable to attend the public meeting in person.

• The webcast allows stakeholders to listen in and view the slides.6 

# Purpose of the Public Meeting

• Present the analytical approaches for the energy modeling used to evaluate energy conservation standards for automatic commercial ice makers (ACIM).

• Invite participants to provide summary comments or statements and raise additional issues for discussion.

• Discuss next steps in the rulemaking, particularly response to comments regarding the engineering analysis.7 

# Opening Remarks

Meeting participants are invited to provide opening remarks or statements at this time.8 

# Public Meeting Topics

1 Introduction and Opening Remarks 2 Background 3 Energy Model Description 4 Use of the Energy Model in DOE’s Engineering Analysis 5 Additional Energy Modeling 6 Discussion9 

# Background

• Energy Policy Act of 2005 (EPACT) P.L. 109

- 58

– Amended EPCA to add coverage for cube type automatic commercial ice makers between 50 and 2,500 pounds of ice per 24 hours.

– Granted DOE authority to set standards for additional types of ACIM equipment that are not covered in EPCA (includes flake and nugget ice makers and batch type ice makers not included in the original EPCA definition).

– Required DOE to complete one rulemaking cycle to determine whether to further amend ACIM standards.

– Final rule required no later than January 1, 2015.


# • NOPR published March 17, 2014.

– The NOPR proposed standards for batch and continuous ice makers with harvest capacity 50 to 4,000 lb/24 hours. 79 FR 14846.


# • NOPR Public Meeting held April 14, 2014.
• Energy Model Meeting today, June 19, 2014.10 

# Rulemaking Stages

Market & Technology Screening Analysis Engineering Analysis Energy Use & End Use Load Characterization Shipments Analysis National Impact Analysis Markups for Equipment Price Determination Life
- Cycle Cost and Payback Period Analysis

Manufacturer Impact Analysis Regulatory Impact Analysis Employment Impact Analysis Utility Impact Analysis
Emissions Impact Analysis 

### Manufacturer Production Cost – Efficiency RelationshipManufacturerProduction Cost



### Efficiency Level (kWh/100 lb ice) 

## Purpose of Engineering Analysis: Characterize manufacturer production cost versus efficiency for higher
- efficiency ACIM equipment. 

# The energy model was used to characterize equipment efficiency in the rulemaking’s engineering analysis.11 

# Public Meeting Topics

1 Introduction and Opening Remarks 2 Background 3 Energy Model Description 4 Use of the Energy Model in DOE’s Engineering Analysis 5 Additional Energy Modeling 6 Discussion12 

# Development of the Energy Model

• FREEZE Model developed by Anthony Varone in 1995.
• EPA Refrigerator Analysis (ERA) program developed by Richard Merriam, used for the 1997 refrigerator rulemaking and updated in 2009 for use in the 2011 refrigerator rulemaking.
• In 2011, Varone and Merriam developed a Windows version of FREEZE, incorporating model features developed for the ERA program.
• Navigant has permission to use the software.13 

# Energy Model The model calculates energy input of the power - using components and ice production for a full icemaking cycle including freeze and harvest.
• Constant Power input P (in watts) for constant
- power components: condenser fan, pump, controls.

• Heat removed from incoming water (or circulating sump water) and heat of fusion removed to make ice represents the thermal load of the evaporator.

• Compressor power input during freeze cycle based on refrigeration circuit/compressor balance.

• Harvest:

– Heat added to the evaporator and water system during harvest cycle sets the freeze cycle start temperatures.

– Harvest duration and energy input are model inputs that can be changed based on knowledge of trends for these parameters. 

## Condenser

Evaporator Compressor TXV

P pump 

## Water In

Drain Water Out Ice Out P comp 

## P fan 

## Controls
P Ctrl14 

# Energy Model For a batch ice maker, the freeze - cycle calculation is conducted numerous times, representing the progression of sump water cooling and ice formation.



# • At each time step, balance of refrigeration system and water/evaporator system determines rate of heat removal from the water and the ice formation.

• Water temperature and ice thickness for the next time step are calculated based on the previous step’s heat removal.

• Time steps run till the calculated ice quantity equals the pre

- harvest ice weight.15 

# Energy Model The full - cycle energy use and ice production are calculated.

• Per
- Cycle Energy Use:

– Condenser fan: Power × cycle time

– Pump: Power × cycle time.

– Controls: Power × cycle time.

– Compressor: Summation for all time steps of power × duration of time step.

– Harvest: Input harvest energy use. This includes operation of all components during harvest, including the fan (if running), pump, controls, and solenoid valve.



# • Per
- Cycle Ice Production: pre

- harvest ice weight minus harvest ice loss.

• Energy Use: Per
- cycle Energy Use divided by Per

- cycle ice production.16 

# Energy Model Compressor power input and mass flow are based on compressor performance data obtained from compressor vendors.

• Performance based on evaporating, condensing, superheat, and subcooling conditions.

• FREEZE adjusts for non

- standard superheat and subcooling.

• Condensing and evaporating conditions based on balance of refrigeration system: compressor, evaporator, condenser.

• For batch ice makers, obtaining good model/test match involves derating compressor map capacity.17 

# Energy Model Refrigeration cycle balance requires that the evaporator and condenser transfer an amount of heat consistent with their sizing and the operating temperature differences.



# • Heat transfer rate (Btu/hr) equal to surface area times heat transfer coefficient times temperature difference ∆ T.

• Heat transfer rate also equal to refrigerant mass flow times refrigerant enthalpy change.

• For condenser or continuous ice maker evaporator, heat transfer rate also equal to fluid mass flow (water or air) times enthalpy change.

• For batch ice maker evaporator, heat transfer rate determines water/ice system start conditions in next time step. ∆ T T refrigerant

T air Air
- cooled condenser18 

# Energy Model Air - cooled condenser modeling and refrigerant - side modeling for the evaporator as developed for the ERA refrigerator model.

• See details in Appendix 5

- B of the 2011 Refrigerator Final Rule TSD: http ://www.regulations.gov/#! documentDetail;D=EERE

- 2008

- BT
- STD

0012

- 0128

• For example, for air

- cooled condensers with plain fin, herringbone fin, and slit fin, airside heat transfer was modeled according to the Wang correlations:

– Wang, Chi

- Chuan, “Recent Progress on the Air

- side Performance of Fin

- and

- Tube Heat Exchangers,” International Journal of Heat Exchangers 1524

- 5608 (Vol 1 (2000), pp. 49

- 76.19 

# Energy Model Water - side modeling for the evaporator using basic calculations for the conduction heat transfer correlated with a polynomial curve fit.

• High thermal conductance at start of cycle
— lower conductance as ice layer builds up.

• Additional thermal resistance for the water film layer. ice film thickness

back film thickness twice the side-film thickness bridge

solder fin one dimensional conduction 

## Example for a 126
- cube evaporator20 

# Energy Model Other model details.
• Continuous ice maker evaporator

– Constant UA value (Btu/hr

- F) to represent heat transfer from water/ice to refrigerant.

– Constant power input P (Watts).

– Ice exit enthalpy based on input for exit ice hardness.



# • Water
- cooled condenser

– Constant condensing temperature.



# • Refrigerant

- flow limit for TXV at start of freeze cycle for batch ice makers.

• Refrigerant properties using REFPROP 8.021 

# Energy Model DOE has adopted procedures to modify model inputs to improve match to test data.

• Compressor capacity derating for batch ice makers.

• Adjustment of harvest cycle inputs for condenser temperature reduction in batch ice makers, based on observed trends in test data.

• Addition of a refrigerant mass

- flow limit to limit the maximum evaporating temperature, based on evaporator conditions measured during testing.22 

# Energy Model DOE used physical testing and teardown data for 41 ice makers in its work on model calibration. Preliminary Phase: Type Equipment Class Harvest Capacity

lb/24 hours Energy Use kWh/ 100 lb Potable Water Use gal/100 lb Energy Test Reverse Engineer ing Energy Use Model

Batch IMH
- A
- Small

- B 270 7.70 20.0    IMH
- A
- Small

- B 324 5.80 22.6    IMH
- A
- Large
- B 780 5.70 20.5   IMH
- A
- Large
- B 844 5.00 18.4   IMH
- A
- Large
- B 1,460 4.95 20.0   IMH
- A
- Large
- B 1,560 4.10 18.8    IMH
- W
- Large
- B 851 4.40 19.7   IMH
- W
- Large
- B 2,820 3.60 19.7    RCU

- A
- Large
- B 1,510 4.59 20.0   RCU

- A
- Large
- B 1,694 3.80 18.1    RCU

- A
- Large
- B 2,350 4.64 19.7   SCU

- A
- Small

- B 121 8.40 17.8    SCU

- A
- Small

- B 112 11.80 34.0   SCU

- W
- Large
- B 285 5.50 18.0   

Continuous IMH
- A
- Small

- C 310 6.31 12.0   IMH
- A
- Small

- C 822 5.51 13.6   IMH
- A
- Small

- C 845 3.40 12.0    RCU

- A
- Large
- C 1,780 3.40 12.0    SCU

- A
- Large
- C 280 6.00 19.0   23 

# Energy Model DOE considered physical testing and teardown data for 41 ice makers in its work on model calibration. NOPR Phase:

Type Equipment Class Harvest Capacity lb/24 hours Energy Use kWh/ 100 lb Potable Water Use gal/100 lb Energy Test Inspecti on Energy Use Model

Batch IMH
- A
- Small

- B 335 6.0 20.0   IMH
- A
- Large
- B 528 6.0 19.1   IMH
- W
- Small

- B 360 4.7 20.0   IMH
- W
- Small

- B 270 6.19 23.9   IMH
- W
- Small

- B 275 6.1 39.0    IMH
- W
- Medium

- B 650 4.1 18.6   IMH
- W
- Medium

- B 832 4.0 18.9   RCU

- NRC

- Small

- B 780 4.7 18.4   RCU

- NRC

- Small

- B 843 5.6 22.8   RCU

- NRC

- Large
- B 2,256 4.34 17.0   SCU

- A
- Small

- B 143 8.48 32.7   SCU

- A
- Large
- B 204 9.5 32.4   SCU

- A
- Large
- B 228 8.6 32.9   

Continuous IMH
- A
- Large
- C 921 6.6 12.0   IMH
- A
- Large
- C 1,100 5.5 12.0   IMH
- W
- Small

- C 560 5.9 12.0   RCU

- NRC

- Small

- C 610 6.9 12.0   RCU

- NRC

- Small

- C 835 5.0 12.0   SCU

- A
- Small

- C 250 9.1 12.0    SCU

- W
- Small

- C 455 5.0 12.0  24 

# Energy Model Demonstration 

# Energy Model25 

# Public Meeting Topics

1 Introduction and Opening Remarks 2 Background 3 Energy Model Description 4 Use of the Energy Model in DOE’s Engineering Analysis 5 Additional Energy Modeling 6 Discussion26 

# Use of the Energy Model in the Engineering Analysis DOE used the energy model to predict energy use reductions.

• Batch ice maker analysis based on ice makers with “waffle

- plate” evaporator making full

- cube (7/8

- inch) ice. No similar restrictions on continuous ice maker analysis.

• Representative baseline ice makers selected for developing cost

efficiency curves:

– Models with efficiency

- level within a few percent of the defined baseline.

– Representative characteristics based on publicly available information (e.g. package size). 

## Develop Baseline

Model Model Alternative Designs Calibrate at Higher Efficiency27 

# Use of the Energy Model in the Engineering Analysis DOE used the energy model to predict energy use reductions.

• Calibrate energy model for the representative baseline ice maker, using the following inputs and calibration checks.

– Physical measurements based on reverse engineering.

– Third

- part laboratory test data at DOE energy test conditions (90  ̊ F/70  ̊ F): Energy use, ice production, refrigerant pressures, temperatures.

– Component power input measurements: fans, pumps, controls, auger motors (while making ice) 

# • Calibration involves adjustment of less certain input parameters within reasonable ranges in order to match observed performance parameters:

– Per
- cycle ice production.

– Cycle time.

– Per
- cycle energy use.

– Refrigerant conditions. 

# • For representative models more than a few percent better than baseline, revise the energy model with less

- efficient design features to represent baseline. Develop Baseline

Model Model Alternative Designs Calibrate at Higher Efficiency28 

# Use of the Energy Model in the Engineering Analysis DOE used the energy model to predict energy use reductions.

• Model energy use for alternative higher

- efficiency designs.

• Calibrate at higher efficiency by ensuring efficiency

- level consistency with max available unit for equivalent design option mix
.

– If max

- available unit was reverse

- engineered: direct comparison of design details for purchased/reverse

- engineered max

- available units.

– Otherwise: compare efficiency level of energy model design with highest

efficiency compressors, increased

- size heat exchangers, and best

- efficiency PSC motors with max

- available level. 

## Calibrate at Higher Efficiency Develop Baseline

Model Model Alternative Designs29 

# Demonstration

Design Option Analysis Walk - Through30 

# Additional Work

• DOE’s contractor has obtained additional information from ice maker manufacturers under non

- disclosure agreement (NDA), and has been promised more information.
• Some of this information addresses model/test discrepancies associated with specific design options
— but not all design options cited in comments as being improperly represented by the model.
• Some of the information will help calibration of model results at intermediate efficiency levels.
• Some information will supplement the modeling results to confirm the cost
- efficiency curve.
• DOE’s contractor is also in the process of obtaining additional cost information under NDA to allow potential revisions of cost projections. DOE’s analysis approach for the final rule will depend on obtaining data to make further model adjustments and allow complementary analysis to confirm results.31 

# Additional Work

• In order to perform further calibration of the energy model, the Department requests test data representing implementations of each of the following design options:

– Compressor replacements

– Increases in evaporator size

– Increases in condenser size (air

- cooled and water

- cooled)

– Application of batch potable water controls

– Efficiencies of available PSC and ECM motors for replacement in current units


# • Model adjustments may be made as adjustments to input or by reducing the improvement associated with the output.32 

# Public Meeting Topics

1 Introduction and Opening Remarks 2 Background 3 Energy Model Description 4 Use of the Energy Model in DOE’s Engineering Analysis 5 Additional Energy Modeling 6 Discussion33 

# Additional Energy Modeling

Model Demonstration with Stakeholder Input Data34 

# Public Meeting Topics

1 Introduction and Opening Remarks 2 Background 3 Energy Model Description 4 Use of the Energy Model in DOE’s Engineering Analysis 5 Additional Energy Modeling 6 Discussion35 

# Energy Conservation Standards - Rulemaking Timeline

2010

ECS Framework Document Public Meeting **December 16, 2010**  ECS Preliminary Analysis Public Meeting **February 16, 2012**
ECS NOPR Public Meeting

**April 14, 2014** 2012 2015 2016 Proposed Energy Conservation Standard Final Rule Compliance Date **To Be Determined**

TP NOPR Public Meeting **April 29, 2011**  2011

Energy Model Public Meeting

**June 19, 2014**36 

# Discussion

Open discussion and closing remarks.