Performance analysis of a novel dual heat source warm air heating system with ecofriendly refrigerants

Abstract

To reduce the energy consumption of the heating, ventilation and air conditioning system, a novel dual heat source warm-air heating system (DWAHS) was developed in this study. A dual heat source air source heat pump was applied to satisfy the warm air segmented handling process first time. The theoretical model of the system was established, and ecofriendly refrigerants, such as R290, R600, R134a, R600a and R1234yf were adopted as the working fluids. The system performance indicators, including the energy efficiency ratio (EER), heat volumetric heating capacities (qv), and exergy loss (Exd), were investigated and compared with those of a conventional single heat source warm-air heating system (SWAHS). The results showed that the DWAHS significantly reduces Exd by handling the supply air segmented using 35 and 60 °C hot water, which were simultaneously supplied by a dual heat source air source heat pump. Among the refrigerants, eco-friendly refrigerants R290 and R600 exhibited the best performance under low and high air-temperature conditions, respectively. Moreover, the DWAHS achieved an increase of 13.3%–64.3% in EER and qv when compared with the SWAHS under different operational temperatures. In addition, the DWAHS reduced the Exd by 13.8%–42.7% compared with the SWAHS. Finally, the Exd of the heat pump consumed a significant part of the warm-air heating system Exd at low environmental temperatures. However, the percentage of the Exd of the air-handling process significantly increased with the temperature of the environment.