Simulation On The Solar-assisted Ground-source Heat Pump Heating System With Seasonal Soil Thermal Storage In The Underground Pit

Based on the studies on the ground-source heat pump, the solar-assisted ground-source heat pump and the solar-assisted ground-source heat pump with thermal storage at home and abroad, this paper proposes the solar-assisted ground-source heat pump heating system with seasonal soil thermal storage in the underground pit. Firstly, in order to get the radiant quantity on the surface of the solar collector and the initial temperature distribution of the soil, the basic theories of the solar energy and the soil were introduced.Secondly, a single building in Beijing was chose and the transient thermal load was calculated by using DEST. According to the maximum thermal load, the system was designed including solar collectors, the underground pit, horizontal buried pipes, the heat pump, circular pumps and the plate heat exchanger. Then, the main operation modes were introduced.Thirdly, the mathematical model of each part of the system was established. The mode conversion conditions of the system were determined. In Beijing, based on the mathematical model of the system, a program was made, and dynamic characteristics of the system and influences of main parameters on the system were simulated and analyzed, including the inclination of the solar collector, the initial temperature of the soil in the underground pit, the area of the soar collector, the thickness of the insulating layer of the underground pit, the water content of the soil in the underground pit, the volume of the underground pit and the heating capacity of the heat pump. Subsequently, the suitable areas to use this system were recommended according to dynamic characteristics of the system in several typical regions.Finally, this system is economically feasible through the economy analysis of the system with the central heating system.The study results of this paper offer beneficial references for the use of the solar-assisted ground-source heat pump heating system with seasonal soil thermal storage in underground pit, and provide the basic data for the further study of the system.