Refrigeration Playbook

Optimizing Heat Rejection and Refrigeration Heat Reclaim for

Supermarket Energy Conservation

Learning Objectives

• Understand basic refrigeration heat reclaim systems and apply this knowledge to create accurate energy models and effective design strategies.

• Calculate the energy impacts associated with reclaiming heat from commercial refrigeration systems in order to confidently guide building owners and designers in optimizing building performance.

ASHRAE is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to ASHRAE Records for AIA members. Certificates of

Completion for non-AIA members are available on request.

This program is registered with the AIA/ASHRAE for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any

material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion

of this presentation.

Acknowledgments

Refrigeration Playbook: Heat Reclaim

Optimizing Heat Rejection and Refrigeration Heat Reclaimfor Supermarket Energy Conservation

August 15, 2014 — December 31, 2014

Chuck Reis, Eric Nelson, James Armer, and Tim Johnson

CTA Architects EngineersBoise, Idaho

Adam Hirsch and Ian DoebberNational Renewable Energy LaboratoryGolden, Colorado

NREL Technical Monitor: Adam Hirsch

Prepared under Subcontract No. LEA-0-40383-01

Agenda

• Why Use Heat Reclaim?

• Why Model Heat Reclaim?

• Project Background

• Refrigeration Cycle Basics

• Common Heat Reclaim Methods

• Tools Available

Why Heat Reclaim?

• What is Heat Reclaim?

• Food Sales: 2nd Highest EUI – 200 kbtu/sf

• Refrigeration: Largest Energy End-Use

• Space Heating: 2nd or 3rd Largest End-Use

• Code Requirements

0

50

100

150

200

250

Site

EU

I (k

btu

/sf-

yr)

Energy Intensity by Sector (2003 CBECS)

Why Model Heat Reclaim?

• Optimize Investment

• Inform Design

• Code Compliance

• 3rd Party Certifications• Energy Savings from “Process Loads”

• Baseline Model Resources• AHRI Standards 540, 1200

• EISA 2007

• DOE 2012 Standards for Commercial Refrigeration

Background

• Create Guide for Designers / Owners /

Contractors

• Identify Common Heat Reclaim Methods

• De-mystify Heat Reclaim

• Transparent Calculation Methods

• Rule of Thumb: Don’t model unless you can write

sequence

• Adapt Methods into EnergyPlus code

• Add a tool to your tool belt

• 17 Locations – All ASHRAE U.S. Climate

Zones

• E+ Model with Spreadsheet Tools

Refrigeration Basics

Refrigeration Basics

Refrigeration Basics

THR

Refrigeration Basics

THR

Condensing

Superheat

THR = Qcond + QDSH

QDSH = m(hD – hE)

Qcond = m(hE - hA)

System Selection

• Look at Big Picture

• Practical Considerations• Budget

• Design Constraints

• Climate

• New or Existing Construction

• Life Cycle Cost

• Initial Cost

• Energy Savings

• Maintenance Costs

General Considerations

• Lower Refrigeration Loads First

• Find Consistent Heating Demand• Space Heat

• OA Preheat

• Domestic Hot Water

• Desuperheat or Full Condensing?• DSH: Higher Temperature, Lower

Quantity

• Condensing: Lower Temperature, Higher Quantity

General Considerations

• DX Reclaim Coil vs. Water Reclaim Coil• DX: More Efficient, More Considerations

• Water: Less Efficient, More Control

• Low Temp vs. High Temp Refrigeration• LT: Higher Discharge Temperature, Lower

Capacity

• MT: Lower Discharge Temperature, Higher Capacity

• Active Maintenance Program

Reclaim Methods

• Service Hot Water (Desuperheat)

• Mixed Air Heating (DSH / Cond.)

• Outdoor Air Preheat (DSH / Cond.)

• Water Loop Heat Pump (Full Condensing)

• Boiler / Cooling Tower

• Ground Loop Heat Exchanger

Service Water Heating

• Usually Desuperheat, DX Coil

• Hourly Tank Temp Calculation:• Weighted Avg. of Tank Temp, Makeup Water Temp

• Reclaim Calculation:• Q = min(Qref, QSHW)

• When Tref > Ttank

• Approach = f(Coil Effectiveness)

Mixed Air Heating

• Desuperheat or Full Condensing

• Q = min(Qref, QHVAC)

• Unless MAT > Tcond

• Approach = f(Coil Effectiveness)

Outdoor Air Preheat

• Simplest Calculation Method

• Condensing Temp > OA Temp

• Q ideal = min(Qair, Qref)

• Q actual = Qideal × Coil Effectiveness

Water Source Heat Pump

• More Complicated Calculation

• Simulation may be required

• Efficiency = f(Loop Temperature)

• Loop Temp = f(QHP, THR)

• Heat Pump Performance Curves

• Loop Temp Control Strategy

• Balance Loads

Other Considerations

• Heat Reclaim Is Not Free Heat!

• Refrigeration Impacts• Condenser Fan Energy (Reduction)

• Piping Configurations

• Pressure Drop (Compressor Energy)

• HVAC Impacts• Coil Airside Pressure Drop

• Coil Waterside Pressure Drop (if applicable)

• Increase Head Pressure to Maximize Heating?

• Increased Heating Capacity

• Decreased Refrigeration Efficiency

• Cost of Refrigeration Heat vs. HVAC Heating

SHW Results(DSH, LT)

No.

ASHRAE

Climate

Zone

Representative City

DHW

Desuperheating

Savings (kbtu)

Space Heating

Full Condensing

Savings (kbtu)

Space Heating

Desuperheating

Savings (kbtu)

Ventilation Full

Condensing

Savings (kbtu)

Ventilation

Desuperheating

Savings (kbtu)

1 1A Miami, FL 265,761 512,782 189,195 -8,879 -14,038

2 2A Houston, TX 264,778 782,508 231,934 110,603 25,414

3 2B Phoenix, AZ 284,859 676,161 204,035 72,113 16,861

4 3A Atlanta, GA 256,082 942,543 262,520 210,782 54,640

6 3B Los Angeles, CA 228,388 1,176,558 334,633 55,856 25,410

5 3B Las Vegas, NV 275,570 898,983 246,113 178,066 47,721

7 3C San Francisco, CA 223,711 1,317,392 330,268 241,068 100,152

8 4A Baltimore, MD 251,461 1,013,205 278,475 330,594 85,328

9 4B Albuquerque, NM 254,925 974,207 270,468 302,007 80,190

10 4C Seattle, WA 230,693 1,271,816 315,505 426,737 124,657

12 5A Chicago, IL 252,309 1,005,135 288,159 399,669 100,007

11 5A Boston, MA 244,659 1,102,669 299,485 419,316 107,921

13 5B Denver, CO 255,031 976,418 281,565 374,205 96,568

14 6A Minneapolis, MN 254,703 1,001,394 292,792 444,013 108,594

15 6B Helena, MT 247,772 1,063,681 301,019 473,759 121,963

16 7 Duluth, MN 246,398 1,103,733 311,989 516,599 131,694

17 8 Fairbanks, AK 249,030 1,133,295 317,776 566,786 144,271

Mixed Air Results(Cond, LT)

No.

ASHRAE

Climate

Zone

Representative City

DHW

Desuperheating

Savings (kbtu)

Space Heating

Full Condensing

Savings (kbtu)

Space Heating

Desuperheating

Savings (kbtu)

Ventilation Full

Condensing

Savings (kbtu)

Ventilation

Desuperheating

Savings (kbtu)

1 1A Miami, FL 265,761 512,782 189,195 -8,879 -14,038

2 2A Houston, TX 264,778 782,508 231,934 110,603 25,414

3 2B Phoenix, AZ 284,859 676,161 204,035 72,113 16,861

4 3A Atlanta, GA 256,082 942,543 262,520 210,782 54,640

6 3B Los Angeles, CA 228,388 1,176,558 334,633 55,856 25,410

5 3B Las Vegas, NV 275,570 898,983 246,113 178,066 47,721

7 3C San Francisco, CA 223,711 1,317,392 330,268 241,068 100,152

8 4A Baltimore, MD 251,461 1,013,205 278,475 330,594 85,328

9 4B Albuquerque, NM 254,925 974,207 270,468 302,007 80,190

10 4C Seattle, WA 230,693 1,271,816 315,505 426,737 124,657

12 5A Chicago, IL 252,309 1,005,135 288,159 399,669 100,007

11 5A Boston, MA 244,659 1,102,669 299,485 419,316 107,921

13 5B Denver, CO 255,031 976,418 281,565 374,205 96,568

14 6A Minneapolis, MN 254,703 1,001,394 292,792 444,013 108,594

15 6B Helena, MT 247,772 1,063,681 301,019 473,759 121,963

16 7 Duluth, MN 246,398 1,103,733 311,989 516,599 131,694

17 8 Fairbanks, AK 249,030 1,133,295 317,776 566,786 144,271

No.

ASHRAE

Climate

Zone

Representative City

DHW

Desuperheating

Savings (kbtu)

Space Heating

Full Condensing

Savings (kbtu)

Space Heating

Desuperheating

Savings (kbtu)

Ventilation Full

Condensing

Savings (kbtu)

Ventilation

Desuperheating

Savings (kbtu)

1 1A Miami, FL 265,761 512,782 189,195 -8,879 -14,038

2 2A Houston, TX 264,778 782,508 231,934 110,603 25,414

3 2B Phoenix, AZ 284,859 676,161 204,035 72,113 16,861

4 3A Atlanta, GA 256,082 942,543 262,520 210,782 54,640

6 3B Los Angeles, CA 228,388 1,176,558 334,633 55,856 25,410

5 3B Las Vegas, NV 275,570 898,983 246,113 178,066 47,721

7 3C San Francisco, CA 223,711 1,317,392 330,268 241,068 100,152

8 4A Baltimore, MD 251,461 1,013,205 278,475 330,594 85,328

9 4B Albuquerque, NM 254,925 974,207 270,468 302,007 80,190

10 4C Seattle, WA 230,693 1,271,816 315,505 426,737 124,657

12 5A Chicago, IL 252,309 1,005,135 288,159 399,669 100,007

11 5A Boston, MA 244,659 1,102,669 299,485 419,316 107,921

13 5B Denver, CO 255,031 976,418 281,565 374,205 96,568

14 6A Minneapolis, MN 254,703 1,001,394 292,792 444,013 108,594

15 6B Helena, MT 247,772 1,063,681 301,019 473,759 121,963

16 7 Duluth, MN 246,398 1,103,733 311,989 516,599 131,694

17 8 Fairbanks, AK 249,030 1,133,295 317,776 566,786 144,271

OA Preheat (Cond, LT)

No.

ASHRAE

Climate

Zone

Representative City

DHW

Desuperheating

Savings (kbtu)

Space Heating

Full Condensing

Savings (kbtu)

Space Heating

Desuperheating

Savings (kbtu)

Ventilation Full

Condensing

Savings (kbtu)

Ventilation

Desuperheating

Savings (kbtu)

1 1A Miami, FL 265,761 512,782 189,195 -8,879 -14,038

2 2A Houston, TX 264,778 782,508 231,934 110,603 25,414

3 2B Phoenix, AZ 284,859 676,161 204,035 72,113 16,861

4 3A Atlanta, GA 256,082 942,543 262,520 210,782 54,640

6 3B Los Angeles, CA 228,388 1,176,558 334,633 55,856 25,410

5 3B Las Vegas, NV 275,570 898,983 246,113 178,066 47,721

7 3C San Francisco, CA 223,711 1,317,392 330,268 241,068 100,152

8 4A Baltimore, MD 251,461 1,013,205 278,475 330,594 85,328

9 4B Albuquerque, NM 254,925 974,207 270,468 302,007 80,190

10 4C Seattle, WA 230,693 1,271,816 315,505 426,737 124,657

12 5A Chicago, IL 252,309 1,005,135 288,159 399,669 100,007

11 5A Boston, MA 244,659 1,102,669 299,485 419,316 107,921

13 5B Denver, CO 255,031 976,418 281,565 374,205 96,568

14 6A Minneapolis, MN 254,703 1,001,394 292,792 444,013 108,594

15 6B Helena, MT 247,772 1,063,681 301,019 473,759 121,963

16 7 Duluth, MN 246,398 1,103,733 311,989 516,599 131,694

17 8 Fairbanks, AK 249,030 1,133,295 317,776 566,786 144,271

Tools Available – E+

• EnergyPlus Capabilities• Service hot water reclaim

• Desuperheat coil

• EnergyPlus Limitations• Mass flow estimation

• No compressor discharge temp

• Superheat ratio – Constant fraction of THR

• No OA preheat coil

• Limited to desuperheat, no full condensing coil

Tools Available – E+

• EnergyPlus Notes:• Microclimates in store / case

credits• Refrigeration Zones

• Room air models

• Compressor coefficients are different from AHRI

• Offset defrost schedules

Refrigeration Front End Spreadsheet

• Refrigeration System Energy

Model

• Refrigerant Property Tables

• Compressor Curves

• TMY3 Weather Data

• Condensing Methods

• Air cooled

• Water cooled

• Evaporative -20

0

20

40

60

80

100

120

-10 0 10 20 30 40 50 60 70 80 90 100 110

Tem

per

atu

re (

°F)

Outdoor Dry-Bulb Temperature (°F)

R404A Low-Temp Condensing Temperature to Outdoor Dry-Bulb Temperature (°F)

Condensing Temperature (°F)

Vapor Temperature (°F)

Outdoor Wet-Bulb Temperature (°F)

Tools Available -Spreadsheets

DOE Commercial Buildings Resource Database

• Refrigeration Playbook: Heat Reclaim: http://www.nrel.gov/docs/fy15osti/63786.pdf

• Space Heating Reclaim Module: https://buildingdata.energy.gov/cbrd/download/1690

• Outdoor Air Preheat Reclaim Module: https://buildingdata.energy.gov/cbrd/download/1687

• Space Heating / Cooling Module: https://buildingdata.energy.gov/cbrd/download/1689

• Refrigeration System Front-End Spreadsheet: https://buildingdata.energy.gov/cbrd/download/1748

• Domestic Hot Water – Hot Water Recovery Calculator: https://buildingdata.energy.gov/cbrd/download/1685

Conclusions

• Why Use/Model Heat Reclaim?

• Common Heat Reclaim Methods

• Domestic Hot Water

• Mixed Air Heating

• OA Preheat

• Heat Pumps

• Calculation Methods

• Tools Available

• EnergyPlus

• Spreadsheets

Resources

1. ASHRAE Handbook – Fundamentals. Atlanta, GA: ASHRAE, 2013; pp. 30.30.

2. “1991-2005 Update: Typical Meteorological Year 3.” National Solar Radiation Data Base, 2015. http://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/

3. “ANSI/AHRI Standard 1200 (I-P)-2013: Performance Rating of Commercial Refrigerated Display Merchandisers and Storage Cabinets.” Air-Conditioning, Heating, & Refrigeration Institute, 2013. http://www.ahrinet.org/

4. “ANSI/AHRI Standard 540-2004 Standard for Performance Rating of Positive Displacement Refrigerant Compressors and Compressor Units.” Air-Conditioning, Heating, & Refrigeration Institute, 2004. http://www.ahrinet.org/.

5. 2013 Nonresidential Compliance Manual, California Energy Commission, 10.5.5, June 2014.

6. 2012 Washington State Energy Code, Commercial Provisions, C403.2.6.3, July 2013.

7. “EnergyPlus Engineering Reference.” (2013). The Board of Trustees of the University of Illinois and the Regents of the University of California through the Ernest Orlando Lawrence Berkeley National Laboratory.

8. “EnergyPlus Input Output Reference.” The Board of Trustees of the University of Illinois and the Regents of the University of California through the Ernest Orlando Lawrence Berkeley National Laboratory, 2013.

9. Energy Conservation Program: Energy Conservation Standards for Walk-in Coolers and Freezers. 10 CFR Part 431. Office of Energy Efficiency and Renewable Energy, Department of Energy (2010): RIN 1904-AB86.

10.Energy Conservation Program: Test Procedure for Commercial Refrigeration Equipment; Final Rule. 10 CFR Parts 429 and 431. Office of Energy Efficiency and Renewable Energy, Department of Energy (April 21, 2014): RIN 1904-AC99.

Questions?

Tim Johnson

TimJ@ctagroup.com