Comparative study on heating performance and economy of air source heat pump coupled with evacuated tube and flat plate collector respectively

Solar evacuated tube collector (ETC) and flat plate collector (FPC), as cost-effective technology for solar utilization, their integration with air source heat pump (ASHP) has shown potential for reducing heating cost. However, a comprehensive comparative study of performance and economy of ETC coupled with ASHP (ETC-ASHP) and FPC coupled with ASHP (FPC-ASHP) heating system is lacking. This study utilized experiment and TRNSYS simulation to compare the performance of ETC-ASHP and FPC-ASHP systems in a 120 m2 building. The results indicate that ETC-ASHP demonstrated better performance and stability. In contrast, FPC-ASHP responded more quickly to changes in solar radiation and ambient temperature enabling faster mode switch. In heating season, ETC-ASHP performed better than FPC-ASHP, with a 15.5 % higher heat collection efficiency, a 7.0 % higher energy efficiency ratio, saved 377 kW h of electricity, reduced dynamic payback period by 0.95 years, and additional reduction of 407 kg in CO2 emissions. ETC-ASHP and FPC-ASHP operated in ASHP, solar assisted heat pump (SAHP), and solar direct supply (SD) three heating modes with respective proportions of heating duration being 25.7 %, 46.5 %, 27.8 %, and 36.5 %, 47.7 %, 15.8 %. Based on the experiment and simulation results, the ETC-ASHP was more suitable for rural winter heating application in cold regions.