The Exergy Analytical And Experimental Research Of Solar Assisted Water Source Heat Pump System

The solar assisted water source heat pump system is a energy-saving building cold and heat source system. In order to further explore the energy saving potential, optimize the system for operation and improve the system, a solar assisted water source heat pump system was used for exergy analysis and experimental study. In this paper, the works and the composition and operation mode and control program were introduced firstly; then the exergy analysis of engineering was introduced, and the exergy analysis model of the system and simulation mathematical model of solar collector system were build; finally the solar collector system was simulated, the system was tested, and the exergy analysis based on the test and simulation results was made.The results show that the COP of the solar assisted water source heat pump system in heating and cold storage (or cold recycling) mode changes between 3.42 ~ 3.57, the comprehensive COP changes between 5.8 ~ 6.2 while the COP of the heating and cold release mode changes between 3.2~ 3.4 under the testing conditions. The exergy efficiency in the mode of the solar collector system with a constant amount of storage tank water and the water temperature increasing is higher than the mode with a constant temperature of the water and the amount of storage tank water increasing. Appropriately increasing the collector standard temperature to connect Ton and the collector standard temperature to disconnect Toff will help improving the exergy efficiency, the exergy efficiency is the highest when the Ton of the system is set at 20℃, and the Toff should not be set at less than 8℃.The exergy efficiency of the system in heating and cold storage mode is higher about 25% than in heating and cold release mode. Respectively, When the system operates in heating and cold storage mode, the average temperature of the water imports and exports from the evaporator should be set to greater than 5℃; when the system operates in heating and cold release mode, the average temperature of the water imports and exports from the evaporator should be set to less than 19℃.There is a great exergy loss rate at the circulating pump, reaching about 22% ,the frequency converter should be added to the circulating water pump drive to adjust the pump speed according to the average temperature of the water imports and exports from the evaporator which should be controlled in 5 ~ 19℃. The initial thermal uniformity tank should be transformed into thermal stratification tank, the frequency converter should be added to the hot water pump to regulate the flow of hot water in order to save energy of the hot water pumps.