Simulation analysis on operation performance of a hybrid heat pump system integrating photovoltaic/thermal and air source

Abstract

• The evaporator model considering dynamic mass flow distribution is established. • The γ for switching between the solar-air mode and the solar mode is about 0.75. • The system performance is less affected by a single environmental factor. • The COP can reach 4.76 and the electric efficiency is 13.5% at 10 °C and 400 W/m 2 . To solve the instability of conventional single source heat pump and further improve energy efficiency, this paper presented a hybrid solar/air dual source assisted heat pump (S-A-AHP) water heater. Based on the system, a quasi-steady-state mathematical model was constructed to study the mode switching criterion and operation performance. The simulation results showed that it is more suitable to use the mass flow ratio of refrigerating medium (i.e., the ratio of the photovoltaic/thermal collector/evaporator to the whole system) as the criterion of system mode switching than directly using environmental factors, and the critical ratio for switching between the solar-air mode and the solar mode is about 0.75. In addition, compared with the conventional solar assisted heat pump (SAHP) and air source heat pump (ASHP), under the low environmental benefit conditions of ambient temperature of 0℃ and solar radiation intensity of 100 W/m 2 , the average COP of S-A-AHP is 29.7% and 19.9% higher than that of SAHP and ASHP, respectively. And the S-A-AHP system's heating time is only 36.7% of the SAHP and 83.7% of the ASHP. And the impact of collector area on system performance was also discussed.