Comparative study of the performance of air and geothermal sources of heat pumps cycle operating with various refrigerants and vapor injection

Abstract

Nowadays, due to the energy and environmental crisis, using renewable energy is considered to reduce environmental pollution. In this paper, a comprehensive review of geothermal source heat pumps (GSHPs) and air source heat pumps (ASHPs) are studied from various aspects including refrigerant change, single-stage heat pump and heat pump with an economizer. This study is conducted to meet the heating needs of the central laboratory of Hakim Sabzevari University. These cycles are analyzed using energy, exergy, and environmental and economic equations (4E analysis). The results show that the coefficient of performance (COP) and exergy efficiency values for the GSHP cycle are higher than the ASHP cycle, and the best refrigerant for both is R134A. The economic and environmental analysis also reveals that using the GSHP cycle can save the electricity to 239 MWh/year (by cycle equipment), which reduces CO2 emissions to 140 tons/year and saves costs 27,280 $/year, compared to ASHP.Moreover, by using an economizer in the heat pump cycle, the COP of the GSHP cycle improved by 9%. The exergy efficiency about 6.8% and the COP of the ASHP cycle grew about 7.5% and its exergy efficiency by 7.4%. It is concluded that the economizer has a more significant impact on the GSHP cycle.

Keywords

• Geothermal source heat pump (GSHP)
• Air source heat pump (ASHP)
• Refrigerant
• Economizer
• 4E Analysis