Abstract
This work compares the annual energy performance of heat pumping systems using R744 and R410A as refrigerant. Focus is the annual energy efficiency of R744 hybrid ground-coupled heat pumping system. The hybrid system uses both ambient air and ground as heat sinks in the cooling mode. This is important to eliminate the underground heat accumulation phenomenon in warm climates. Several quasi-steady state models of heat pumping systems, using R744 and R410A, have been developed. Simulation results show that the annual COPc and COPh of an R744 hybrid system reaches 3.55 and 3.32, and its cooling performance is 42% better than for a R744 ASHP and 23% better than for a R744 GCHP system. The annual energy performance factor of a R410A ASHP system is better than for a R744 hybrid system, but the COPc for the R410A system will be lower when the ambient temperature is higher than 30 °C. © 2017 Elsevier Ltd. All rights reserved.