Comparative study of air source and ground source heat pumps in 10 coldest Russian cities based on energy-exergy-economic-environmental analysis

As one of the environmentally friendly technologies, heat pumps have been widely utilized in residential and commercial buildings all over the world. The use of renewable energy sources and environmentally friendly refrigerants are two major challenges associated with heat pumps applications. Due to the advantages of cascade heat pumps over single-stage heat pumps and the higher energy demand met by cascade heat pumps, investigation of the effects of geographic conditions (weather and soil conditions) as well as the simultaneous use of two refrigerants for high and low temperature cycles on performance of cascade heat pumps would provide critical information for practical applications. This paper compares the performance of air source and ground source cascade heat pumps using refrigerants by low global warming potential and zero ozone depletion potential in top 10 coldest cities of Russia. The effects of variations in temperature of evaporator and cascade heat exchanger on optimal operational conditions are investigated based on energy, exergy, economic and environmental analysis using Pareto front curve. Optimization results show that there is an optimal point for evaporator temperature and cascade heat exchanger temperature where the maximum COP, maximum exergy efficiency and minimum total cost rate for ASHP and GSHP systems are obtained. It is found that at low air temperature, since the underground temperature is higher than ambient air, the efficiency of GSHP system is better than efficiency of ASHP system. The maximum COP of 2.357 and 2.44 are respectively obtained for ASHP and GSHP systems in Saint Petersburg. In addition, Yakutsk city has the maximum exergy efficiency of 40.7% and 43.2% and maximum total cost rate of 14714 $ year 1 and 13693 $ year 1 for ASHP and GSHP systems, respectively. Finally, it is concluded that Saint Petersburg is the best city to employ ASHP system while GSHP system is suggested for Khabarovsk city.