Study On The Performance Of The Heat Pump With Different Grade Copling Of Solar Energy And Air Source

Energy shortage and environmental pollution caused by fossil energy are the main problems faced by China in the implementation of sustainable development strategy.The proportion of heating energy consumption to total building energy consumption is also increasing in China.Clean heating can alleviate the problem of energy and environmental pollution.It is a clean heating mode to integrate solar energy heat collection system with air source heat pump system.It can use solar energy to assist air energy to solve the problem of poor low temperature performance of air source heat pump..At the same time,it has practicability,environmental protection and economy.Based on the comparison of the existing solar-assisted air source heat pump systems,a new heat pump system with different-grade coupling of solar energy and air source is proposed in this paper.The solar energy is arranged in the middle branch of the two-stage compression,and the collector temperature and pressure of the solar collector are between the condenser and the evaporator.The new system was studied by both simulation and experimental methods.According to the utilization temperature of solar energy,the existing solar-assisted air source heat pump systems were divided into two categories.The mathematical model of two typical existing systems and the newly proposed solar-air stage coupled heat pump is solved by using MATLAB software.The component models of the three systems adopt steady-state modeling method,and the component models of the three systems are consistent.Under the same outdoor temperature,solar radiation intensity,the degree of subcooling and superheating,the thermal performance of the three systems was compared.The results show that when the outdoor temperature is-25 C,the COP of the new system is 55% higher than that of the existing typical solar assisted air source heat pump system.By changing the operation mode,the new system can maintain a high COP.Moreover,in the new system,the interaction between solar energy and air energy is very small.The applicable operating range of each system is obtained by simulation.The influence of different condensing temperature and heat collecting area on the optimal operating conditions of each system is emphatically analyzed.With the increase of collector area and condensation temperature,the optimal operating range of the new system will be further increased.An experimental platform was designed and built of the new heat pump system with different-grade coupling of solar energy and air source to analyze the performance of the moderate temperature collector system in the simulation part in Jilin city.The experimental station mainly includes air source heat pump system,solar collector system,cooling water circulation system and data acquisition system.According to different outdoor meteorological parameters,different operation modes can be realized by adjusting valves.The results of the test in Jilin City are as follows:(1)During the transition season,the heat production of pure air source heat pump system and solar direct supply system can meet the heat load.However,air source heat pump units need frequent start-up and shutdown,otherwise the heat generated exceeds the heat load,which will affect the life of the unit,and increase energy consumption.Comparing COP,the average COP of solar direct supply system is 9 times higher than that of air source heat pump system.(2)During winter operation,the average heat production of the stage coupled heat pump system is 26.02 kW,The heat production of the new system is 35.73% higher than that of the traditional system.The average COP of the hierarchical coupled heat pump system is 3.39,The COP of the new system is 21.51% higher than that of the traditional system.With the decrease of temperature,the advantages of the new system in heating performance will be more obvious.The new heat pump system with different-grade coupling of solar energy and air source,as a clean heating mode,is of great significance to energy saving,emission reduction and environmental protection in China.