Heating and electricity generation performance investigation of a novel ejector enhanced photovoltaic-thermal heat pump

With the aim of enhancing heat pump performance to the greatest extent possible, a novel ejector enhanced photovoltaic-thermal heat pump (EPHP) is proposed in this study. The heating and electricity generation performance of EPHP is theoretically investigated from energy, exergy, economic and environmental aspects. The heating coefficient of performance (COP) and capacity of EPHP are found to be slightly superior to those of convenient ejector enhanced heat pump (EHPC). Furthermore, the synthetical COP of EPHP substantially exceeds the heating COP of EHPC by 55.1 %–36.4 %, benefiting from the electricity feedback from photovoltaic-thermal module. Meanwhile, EPHP always produces better performance over EHPC under all solar radiation conditions. The heat exergy output of EPHP increases by 6.6 % with a solar radiation intensity increment of 900 W m−2, while the exergy efficiency reduces from 18.6 % to 6.9 %, hindered by the substantial irreversible loss in photovoltaic-thermal module. In a typical winter day of Beijing, EPHP respectively reduces the total electricity consumption in daytime and whole day by 6.2 % and 12.5 %. The payback period of EPHP is 6.54 years, accompanied by remarkable reductions of pollution emissions. According to multi-objective optimization, the optimal combination of synthetical COP and levelized cost of energy is located at [5.36, 0.069 $·kWh−1].