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Assessing low-GWP refrigerants in ground source heat pump systems: long-term thermal performance under varied geological conditions and cold climate.

Number: 3212

Author(s) : ZHAO Z., LV G.

Summary

The existing ground source heat pump (GSHP) systems are widely utilizing R410A as the primary refrigerant. As a replacement for R22, which was phased out due to its ozone-depleting potential, R410A can operate at a higher pressure and deliver improved energy efficiency in heat pump systems. However, the urgent objective of achieving carbon neutrality in the coming decades necessitates a continuous reduction in greenhouse gas emissions. This can be realized by incorporating more low-global warming potential (low-GWP) refrigerants into GSHP systems. Simultaneously, it is crucial to recognize that the subsurface environment may affect the thermal efficiency of the refrigeration system, which has not been examined in documented studies. In this study, a typical residential building operating under cold climate is first created and dynamically modeled in TRACE3D Plus. Furthermore, two most potentially applicable alternatives—R454B and R32 are explored as the working fluids in a GSHP model in TRNSYS. To evaluate the long-term impacts of different refrigerants on the subsurface overcooling and the degradation of GSHP efficiency, a lifespan operation of GSHP combining the building load profile is simulated. In
the meantime, to assess the responsiveness of different refrigerants to environmental fluctuations, sets of heterogeneous geological units, comprised of varied ground thermal conductivities, layered thickness, and ground heat capacities, are integrated into the model as inputs. The varied thermal behaviors exhibited by refrigerants are carefully examined to analyze their influence on the heat pump operation. The results showed non-negligible differences when obtaining the annual coefficient of performance (COPs) and excessive ground cooling resulting from different combinations of refrigerants and diverse geological contexts. This study may provide insights for future optimization of GSHP systems.

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  • Original title: Assessing low-GWP refrigerants in ground source heat pump systems: long-term thermal performance under varied geological conditions and cold climate.
  • Record ID : 30032956
  • Languages: English
  • Source: 2024 Purdue Conferences. 8th International High Performance Buildings Conference at Purdue.
  • Publication date: 2024/07/15

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