Performance simulation and experimental study of solar heat pump water heating system with micro-channel collector/evaporator

Presents a novel micro-channel collector/evaporator which uses the tree branch model and is made of two pieces of aluminum plates by the method of cold rolling and blow molding. It reduces the contact thermal resistance and improves the heat transfer coefficient. Integrates the heat collector/evaporator into a solar heat pump water heating system. Presents the mathematical model of the heat collector/evaporator. Through the simulation and experimental research, analyses the variation characteristics of the system COP, heat collecting efficiency, heating time of hot water and operating parameters under different ambient conditions. The results show that when heating 150 L water from 15 ℃ to 50 ℃, the annual average system COP, heat collecting efficiency and heating time are 4.8, 1.3 and 314 min, respectively. The heat collecting efficiency increases evidently with the increase of ambient temperature and the decrease of solar irradiance. The system simulation results are in good agreement with experimental ones, which indicates the feasibility of the method of calculation and mathematical model.