An Evaluation of the Environmental Impact of Different Commercial Supermarket Refrigeration

Systems Using Low Global Warming Potential Refrigerants

Paper 2278

Mohamed Beshr, Vikrant C. Aute (vikrant@umd.edu), Omar Abdelaziz, Brian Fricke, Reinhard Radermacher

15th International Refrigeration And Air Conditioning Conference at Purdue, July 14-17, 2014, Purdue, Indiana

ContentsIntroductionProject ObjectivesLife Cycle Climate Performance (LCCP) FrameworkCase StudiesConclusions

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INTRODUCTION

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Life Cycle Climate PerformanceTotal CO2 equivalent global warming impact over total lifetime of the systemComprised of

Direct emissions: refrigerant releasedIndirect emissions

Energy consumption over lifetime and recyclingPower input during operation, transport, processingManufacturing of systems/components, recycling

Units: CO2eq

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Direct Emissions

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direct ref,leak acc serv ref,EOL ref,prod reactionEm = Em + Em + Em + Em + Em + Em

ref,leakEm = Charge System lifetime Annual leak rate GWP

accEm harge System lifetime Annual accident leak rate= GWC P

servEm Total number of services Charge Servicing leak rate W= G P

ref,EOLEm Percent of refrigerant lost at end of life Charge = GWP

ref,prodEm = Ref production & transportation leak rate Charge GWP

Indirect Emissions

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indirect sys,man ref,man sys,EOL ref,disp elec sys,transEm = Em + Em + Em + Em + Em + Em

sys,man 2eqEm = Mass of each material CO

ref,man

2eq

Em = Charge (1 + System lifetime Annual leak rate – Percent of reused refrigerant) CO emissions for

virgin refrige

rant

sys,EOL

2eq

2eq

Em = Energy of recycling of metals Mass of metals

CO of metals + Energy of recycling of plastics

Mass of plastics CO of plastics

8760

sys,elec0

Em = System lifetime Hourly energy consumed Emission

rate for location n

PROJECT OBJECTIVES

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LCCP ObjectivesDesign ToolBuild on existing methodologiesExtensible framework for LCCP design

Can be coupled with existing system/load calculation toolsSupermarket refrigeration, heat pumps, display cases, water chiller

Open SourceDesktop and Web based interfaces

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LCCP FRAMEWORK

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LCCP Framework

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LCCP Calculation Methodology

LCCP

System Model Load Model

Emission & Weather Database

Interfaces for std.data communication

Components are developed as “Open Source”.Other components can be open-source or proprietary

System Performance Models:ORNL HPDM, VapCyc, in-housemodelsPerformance maps based on catalog data or experimentsCan be coupled with Load Model for more sophisticated modeling

Hourly Load Data:Energy Plus, DOE-2, TRNSYS,simplified load profiles,hourly load profile via text file

Databases:NREL LCE database, eGRID,TMY3 weather data,…

Accessing LCCP Toolhttp://lccp.umd.edu

Web versionDesktop version downloadUser guideIntroductory video

Engineering Referencehttp://info.ornl.gov/sites/publications/Files/Pub49128.pdf

Google: “ORNL LCCP”

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CASE STUDIES

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Supermarket System ModelEnergyPlus used for system hourly performance4181 m2 single-story supermarket Floor-to-ceiling height of 6.1 m Based on the new construction reference supermarket model developed by the U.S. Department of Energy (Deru et al., 2011)Divided into six zones (office, dry storage, deli, sales, produce and bakery)

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Supermarket System Model

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Compressor Rack

Refrigeration Load (kW)

Charge (kg)

Source of Mechanical Subcooling

MT1 167.1 748 --MT2 52.8 236 --LT1 64.6 290 MT1LT2 23.4 104 MT2

Total: 307.9 1378

Refrigerant Composition GWPR-404A R-125/R-134a/R-143a 3943R-407F R-125/ R-134a /R-32 1674N-40 R-125/ R-134a /R-32/R-1234yf/R-1234ze 1273

Supermarket System Model

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Climate Zone City Annual Average Temperature (°C)1A Miami, FL 24.92B Phoenix, AZ 23.83B Los Angeles, CA 17.34C Seattle, WA 11.45A Chicago, IL 10.06B Helena, MT 7.27 Duluth, MN 4.38 Fairbanks, AK -2.1

Annual leakage rate 10 %Refrigerant loss at end-of-life 10 %System lifetime 20 yearsService interval 2 yearsService leakage rate 5 %Reused refrigerant 85 %

Results – Direct Emissions

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0

2000

4000

6000

8000

10000

12000

14000

16000

R‐404A R‐407F N‐40

Total D

irect Emissions

[Ton

s CO2eq]

Results – Indirect Emissions

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0

200

400

600

800

1000

1200

0

2000

4000

6000

8000

10000

12000

14000

R-4

04A

R-4

07F

N-4

0R

-404

AR

-407

FN

-40

R-4

04A

R-4

07F

N-4

0R

-404

AR

-407

FN

-40

R-4

04A

R-4

07F

N-4

0R

-404

AR

-407

FN

-40

R-4

04A

R-4

07F

N-4

0R

-404

AR

-407

FN

-40

Miami Phoenix LosAngeles

Seattle Chicago Helena Duluth Fairbanks

Ann

ual E

lect

ricity

Con

sum

ptio

n [M

W-h

]

Tota

l Ind

irect

Em

issi

ons

[Ton

s C

O2e

q]

Total Indirect Emissions Annual Electricity Consumption

Results – Total Emissions

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0

4000

8000

12000

16000

20000

24000

28000R

-404

AR

-407

FN

-40

R-4

04A

R-4

07F

N-4

0R

-404

AR

-407

FN

-40

R-4

04A

R-4

07F

N-4

0R

-404

AR

-407

FN

-40

R-4

04A

R-4

07F

N-4

0R

-404

AR

-407

FN

-40

R-4

04A

R-4

07F

N-4

0

Miami Phoenix LosAngeles

Seattle Chicago Helena Duluth Fairbanks

Em

issi

ons

[kgC

O2-

Eq]

Indirect Emissions Direct Emissions

Sensitivity Analysis - Charge

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0123456789

R-404A R-407F N-40 R-404A R-407F N-40 R-404A R-407F N-40

Miami Seattle Chicago

Cha

nge

in L

CC

P, %

10% change in the refrigerant charge on total emissions

Sensitivity Analysis - Emissions

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012345678

R-404A R-407F N-40 R-404A R-407F N-40 R-404A R-407F N-40

Miami Seattle Chicago

Cha

nge

in L

CC

P, %

10% change in the hourly emission rate for electricity production on total emissions

Uncertainty AnalysisLocated in Chicago and Seattle Using R-404A and N-40

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Input Uncertainty, %Case 1 Case 2 Case 3

Reused refrigerant 20 20 20Service leakage rate 20 20 20Refrigerant loss at end-of-life 20 20 20Annual leakage rate 20 20 20Charge 5 5 5Power plant emission 5 5 20Refrigerant GWP 20 5 5

Uncertainty Analysis

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Partial derivatives of the total emissions with respect to each of the input parametersChicago Seattle

Partial derivative Partial derivative

R-404A N-40 % diff. R-404A N-40 %

diff.Reused refrigerant -2.3E+04 -1.1E+04 -52.10 -2.3E+04 -1.1E+04 -52.10Service leakage rate 5.4E+07 1.8E+07 -67.71 5.4E+07 1.8E+07 -67.71Refrigerant loss at end-of-life 5.4E+06 1.8E+06 -67.71 5.4E+06 1.8E+06 -67.71Annual leakage rate 1.1E+08 3.5E+07 -67.65 1.1E+08 3.5E+07 -67.65Charge 1.0E+04 3.3E+03 -67.66 1.0E+04 3.3E+03 -67.66Power plant emission 1.5E+07 1.4E+07 -3.62 1.4E+07 1.4E+07 -3.49Refrigerant GWP 3.6E+03 3.6E+03 0 3.6E+03 3.6E+03 0.00

Case 1 Case 2 Case 3Chicago Seattle Chicago Seattle Chicago Seattle

R-404A N-40 R-404A N-40 R-404A N-40 R-404A N-40 R-404A N-40 R-404A N-4015.8 9.4 21.9 16.8 10.7 6.8 14.7 11.3 13.2 14.5 15.0 13.3

Uncertainties (%) in the system's LCCP

CONCLUSIONS

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ConclusionsA flexible tool for LCCP based design and evaluation of supermarket refrigeration systems is developedThis framework is open-source and can be easily extended to the analysis of other vapor compression technologiesThis LCCP tool was used to compare the environmental impact of using three different refrigerants in a supermarket refrigeration system in eight US cities

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ConclusionsN-40 is more environmentally friendly in the different climates for the system investigatedShifting towards lower GWP refrigerants:

Increases the effect of the hourly emission rate for electricity production on the total system emissionsCauses a large drop in the impact of the uncertainty in the inputs related to the direct emissions

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Thank You

This work was supported in part by the Oak Ridge National Laboratory (ORNL) and the IntegratedSystems Optimization Consortium (ISOC) at the University of Maryland. The authors alsoacknowledge the support of Building Technologies Office of the US Department of Energy for theirfinancial support. Furthermore, the authors acknowledge the support of Dr. Samuel Yana Motta, Dr.Ankit Sethi, and Honeywell International Inc. for their in-kind and technical support.

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LCCP Applications ComparisonASHP system

LCCP Application AHRI ORNL-LCCPMS Excel based Web Desktop

Design Capability No Yes YesSystem Type 3 + custom 3 3 + custom

Units English/SI English/SI/Modified English/SI/ModifiedNo. of Cities 41 + User defined 41 41 + User definedRefrigerants 13 + User defined 13 13 + User definedPerformance Calculation

AHRI std/SimpleSEER

AHRI std/SimpleSEER

AHRI std/SimpleSEER

CO2 from Manufacturing/EOL Simple/Detailed Simple Simple

AHRI tool: http://www.ahrinet.org/technical+results.aspx

Supermarket refrigerationDesign capability

Residential air source heat pumpEvaluation and design capabilityANSI/AHRI Standard 210/240

UMD-ORNL LCCP tools: http://lccp.umd.edu/

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Web Application

ASHP system evaluation tool

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Web Application

• Test data inputs according to AHRI std 210/240

• Required for LCCP evaluation

General system inputs

Required for backup heat with gas/oil

ASHP system design tool

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Web Application

Similar to evaluation tool

• System sizing details

• Required for design based on LCCP

Desktop ApplicationSystem

VapCyc basedInterchange component modelsRefrigerant mixturesUser-defined components and fluids

User-defined Loads

Text fileEnergyPlusUser defined

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Desktop App (contd.)TMY3 weather dataSystems with multiple cycles Comparison of different systemsMulti-dimensional parametric analysisSensitivity analysisUncertainty analysisEffect of charge degradation on system performance

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