Heating characteristics of air-water hybrid source heat pump and its matching with building heat load

This study investigates the heating characteristics of an air–water composite source heat pump (A-WSHP) and its matching relationship with building heat load under frost-free operation. An experimental platform for a finned-tube evaporator was developed and combined with CFD simulation and ANN modeling to analyze coupled heat transfer, heating capacity, and heat load matching. Results show that the composite heat source significantly improves evaporator heat exchange and heating capacity in low-temperature environments compared with a conventional air-source heat pump. The ANN model accurately predicts evaporator heat absorption and outlet air temperature, with R values above 0.9998 and a low MSE of 5.2599×10 - 3 . The heat load matching ratio increases almost linearly from 1.20 to 3.12 as the evaporator hot-water temperature rises from 3°C to 25°C. Under Changsha winter conditions, a single air-source heat pump requires frequent auxiliary heating, whereas the A-WSHP supplied with 15°C hot water can achieve frost-free operation throughout the heating season without auxiliary heat. These findings support the optimized design and efficient operation of composite source heat pumps. Practical Application This study provides building professionals with a practical basis for applying air-water composite source heat pumps in cold and humid climates. By clarifying frost-free heating performance, hot-water temperature effects, and heat-load matching, the results support evaporator sizing, auxiliary heat reduction, and low-grade heat recovery strategies. The proposed CFD-ANN prediction approach can assist engineers in selecting operating conditions and designing more reliable, energy-efficient heating systems for modern buildings.