Study On Energy-saving Operation Of A Combined Heating System Of Solar Hot Water And Air Source Heat Pump

The improvement of social economy condition has raised people’s requirements for indoor thermal environment comfort.In recent years,the severe cold weather has frequently occurred in the south,and the voice of building heating in the south has become more and more loud,which has further increased the energy consumption of building heating in my country.need.The development of renewable energy sources such as solar energy and air energy is an important way to alleviate energy demand.The combined heating system has been promoted rapidly because of its good reliability and energy saving,but the intermittent and low energy consumption of solar energy resources.Outdoor air temperature is still an important factor affecting system performance.How to improve the utilization rate of solar energy and air energy,optimize the configuration of system components,and enhance the heating performance of the system are the research priorities to further promote the development of combined heating technology.In order to make full use of the utilization rate of renewable energy,this paper proposes a composite heating system that can switch operating modes according to outdoor meteorological parameters.According to the heat and mass transfer theory,the heat transfer mechanism of the main components of the compound system is analyzed,and the calculation model of the heat supply performance of the compound system is established.An experimental platform for the combined heating system of solar energy and air source heat pump was built,and the water circulation between the solar collector and the evaporator hot water coil was taken as the research object.The water temperature was tested experimentally.The TRNSYS model of the composite system is established,and the heat transfer model of the composite system is verified.The biggest error of the inlet water temperature of the hot water coil is 10.61%,and the average error is 2.21%;the maximum error of the outlet water temperature of the hot water coil is 9.70%,and the average error is 2.94%;the maximum error of heat exchange is 11.63%,and the average error was 5.27%.The experimental values are in good agreement with the simulated values,and the established composite TRNSYS model has good accuracy.Taking the parallel mode,the series mode and the preheating mode in the compound system as the research objects,the heating performance of the three modes under different environmental parameters was simulated and analyzed.The effect of solar collector area and return water temperature on the optimal energy efficiency area map.The optimal energy efficiency area of the preheating mode is mainly at low solar radiation intensity,and the lower the air temperature,the larger the optimal energy efficiency area.The optimal energy efficiency area of the parallel mode is mainly under high solar radiation intensity,and the lower the air temperature,the smaller the optimal energy efficiency area.The optimal energy efficiency region for series mode is between parallel mode and preheat mode.The change of the return water temperature and the change of the area of the solar collector can change the distribution of the best energy efficiency area.Among the three connection methods,the change of the return water temperature has the greatest impact on the series-connected area,and the smallest impact on the parallel-connected area.The area change of the radiator has the greatest effect on the area of parallel mode and the least effect on the area of preheat mode.Taking Xiangtan area as an example,the optimal energy efficiency area map of preheating mode,series mode and parallel mode in the composite system is obtained,and the operation control strategy of the composite system is determined.The simulation models of parallel system,series system,preheating system and compound combined heating system are established in TRNSYS.Through the simulation calculation,the SPF value of the composite system is 8.4%,15.8%,and 7.1% higher than that of the parallel,preheating and series combined heating systems,respectively.The composite system can obtain good energy-saving benefits for heating in Xiangtan area.