Sharif Digital Repository

This paper discusses a technical comparison of a directexpansion ground-source heat pump (DX-GSHP) and an airsource heat pump (ASHP). To lower the ground heat exchanger size for cost reduction purposes, the system performance of a hybrid system is also evaluated using a supplementary air evaporator combined with the DX-GSHP. Detailed screening models previously developed for ASHPs and DX-GHSPs are first used to compare the seasonal performance of these two options for a residential building in the cold-climate city of Montreal, Canada. Then, the model is adopted for performance evaluation of the hybrid system. Additionally, different parameters including borehole total length and heat pump... 

This paper addresses the challenge of improving the performance of heat pumps (HPs) in cold-climate conditions by applying refrigerant mixtures. The potential benefits of implementing R-32/CO2 zeotropic refrigerant mixtures in three different residential air-source HPs for cold climates are studied. The cases considered are conventional residential HP, HP with a variable mixture control system, and HP with a variable compressor speed. The seasonal performance of a heating system with these air-source HPs, supplemented with an auxiliary electric heater, is studied in the cold-climate city of Montreal, Canada. To this aim, a detailed screening HP model previously developed is modified and...