Research On Performance Of Collector/Evaporator Of Direct-expansion Solar/Air-assisted Heat Pump

In urban and rural areas,with the continuous improvement of the living environment and living standards,residents have higher and higher requirements for heating comfort.In order to solve the problem of poor heating effect of traditional heat pumps in cold areas,a new direct-expansion solar/air-assisted heat pump has been put forward.It uses renewable energy instead of traditional coal and natural gas to heat public buildings and houses in cold regions.It avoids the shortcoming of unsteady operation performance of traditional solar heat pump.When the solar radiation is insufficient or absent,the heat in the air can be absorbed,which greatly improves the heating efficiency during system operation.To further perfect the heating performance of the direct-expansion solar/air-assisted heat pump system,the structure and material of its collector/evaporator were optimized by using computational fluid dynamics method.The models of the collector/evaporator with different structures were established by using software ICEM,and the operation of the heat pump system in a two-story building in rural Handan was tested experimentally for 5 days.The experimental values of the solar/air energy collector/evaporator at each working condition from 10:00 to 15:00 on the first day of March were selected for comparison and analysis with the simulated values,in a bid to verify the correctness of the simulation results.The experimental value and simulation value of the collector/evaporator under various working conditions are compared and analyzed.Under the same meteorological conditions,the Fluent fluid simulation software was used to simulate and calculate several key parameters such as tube diameters,fin heights,fin thicknesses,fin numbers and the collector/evaporator materials.On this basis,its heat collection capacity and efficiency are evaluated.Comprehensively considering the heat collection capacity,heat collection efficiency and manufacturing cost,the optimal structure of the collector/evaporator is obtained.Finally,the optimized collector/evaporator is numerically simulated under different outdoor temperature,solar radiation intensity and outdoor wind speed to further verify the feasibility of the collector/evaporator structure optimization.By optimizing the structure of the collector/evaporator through simulation research,the thermal performance of the collector/evaporator of a direct-expansion solar/air-assisted heat pump is further improved,and the operating cost of the heat pump system is reduced.It is of great significance to improve the solar thermal utilization technology,reduce building energy consumption,and alleviate environmental pollution in China.