Abstract

Heat pumps (HPs) are being developed with a new emphasis on cold climates. To lower the environmental impact of greenhouse gas (GHG) emissions, alternate low global warming potential (GWP) refrigerants must also replace the exclusive use of the refrigerant R410A, preferably without re-engineering the mechanical hardware. In this paper, we analyze the performance of four low-GWP alternative refrigerants (R32, R452B, R454B, and R466A) relative to the conventional R410A and draw conclusions on the relative performances for providing heating in cold climates based on the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) 210/240 standard for two-speed heat pumps. The simulations are carried using the Department of Energy, Oak Ridge National Laboratory (DOE/ORNL) Heat Pump Design Model (HPDM), a well-known heating, ventilation, and air conditioning (HVAC) modeling and design tool in the public domain and the HVAC research and development community. The results of the simulation are further scrutinized using exergy analysis to identify sources of systemic inefficiency, the root cause of lost work. This rigorous approach provides an exhaustive analysis of alternate low-GWP refrigerants to replace R410A using available compressors and system components, without compromising performance.

Highlights

  • The earth continues to experience record increases in surface temperatures, largely caused by anthropogenic activity

  • This paper addresses the research question of replacing currently used R410A with low global warming potential refrigerants for cold climate heat pumps, in which there is a gap in current knowledge and performance assessment especially related to drop-in replacements

  • Through an extensive literature survey, we identified heat transfer and pressure drop correlations suitable for modeling and optimizing air conditioners and heat pumps, and valid for various low global warming potential (GWP)

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Summary

Introduction

The earth continues to experience record increases in surface temperatures, largely caused by anthropogenic activity. This paper addresses the research question of replacing currently used R410A with low global warming potential (low-GWP) refrigerants for cold climate heat pumps, in which there is a gap in current knowledge and performance assessment especially related to drop-in replacements. The application in cold climate conditions, and operation at the temperature levels of the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) 210/240 standard for two-speed heat pumps are new, relative to drop-in low-GWP refrigerants. Energies 2020, 13, 5666 pumps for simultaneous heating and cooling [20], but not to the specific issue of providing heating in cold climates based on the AHRI 210/240 standard for two-speed heat pumps by replacing R410A with low-GWP refrigerants. The R410A replacements are mostly blends containing R32 and hydrofluoroolefin (HFO) R1234yf, as well as a pure refrigerant, R32 They have approximately 70% lower global warming potential (GWP) than R410A. R410A has compositions of R32 (0.5)/R125 (0.5), mass based; R452B has R32 (0.67)/R125 (0.07)/R1234yf (0.26), mass based; c R454B has R32 (0.689)/R1234yf (0.311), mass based; d R466A has R32 (0.49)/R125 (0.115)/R13I (0.395), mass based

Refrigerant Properties
Compressor Model
Heat Exchanger Model
Baseline Heat Pump and Rating Conditions
Component-Wise Irreversibility
Results and Discussion
Conclusions
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