Performance Comparison of Air Source Heat Pump Coupling with Solar Evacuated Tube Water Heater and that with Micro Heat Pipe PV/T

Air source heat pump (ASHP) has been generally regarded as energy saving devices for winter heating, yet for low-income households, the operational costs for heating in low-temperature conditions may be prohibitively high. Solar evacuated tube water heater (SETWH) and photovoltaic/thermal are economical solar energy conversion devices. Integrating them into ASHP has been proven globally to significantly reduce heating costs. However, a performance comparison between the SETWH combined with ASHP (SETWH-ASHP) and of micro heat pipe photovoltaic/thermal (MHP-PV/T) combined with ASHP (MHP-PV/T-ASHP) heating systems remains unexplored. Therefore, for a 120 m2 building with underfloor heating water pipe, SETWH-ASHP and MHP-PV/T-ASHP heating systems were respectively developed on the TRNSYS software platform. Their accuracy was confirmed using prior experimental data, followed by performance simulation for the heating season. The result is that MHP-PV/T-ASHP heating system outperformed SETWH-ASHP heating system, showing a 19% increase in solar fraction, a 2.2 boost in system energy efficiency ratio, a 12.3% rise in primary energy saving rate, a 0.9-year shorter payback period, and a reduction of 494.7 kg in CO2 emissions over the heating season. The results offer practical guidance for the promotion and application of heating systems that combine efficient and low-cost solar conversion devices with ASHP.