Study Of Geothermal Heat Exchanger For Integrated System Soil Thermal Storage And Ground-source Heat Pump

Ground-coupled heat pump has two problems, one is that the space occupied by the coil is too large, another is that the annual imbalance between heating and cooling loads of the geothermal heat exchangers. The on and off-peak electric load of the power grid will aggravate the tension of the power supply. Combined the advantages of both soil thermal storage technology and the ground-source heat pump, a integrated system of soil thermal storage and ground-coupled heat pump which can solve the problems above is presented. The advantages of the soil thermal storage and GCHPS are fully utilized in the system, and the underground heat exchangers of the GCHPS are also served as the soil thermal storage equipments simultaneity.Based on energy balances, a 3D mathematic model of soil thermal storage and release process of geothermal heat exchangers was established by the thermodynamics analysis of the double functions pipe heat transfer process. The influences of the tube material, the back-fill material, soil type, borehole depth, pipe distance and thermal pre-storage time on the operation performances were analyzed. Moreover, Based on the operation mode in summer or winter, the structure of geothermal heat exchangers was optimized. It provided theory support and technology accumulation for the optimal design of the underground heat exchangers and the matching of the parameters.The research indicated that the integrated soil thermal storage and ground-coupled heat pump heat pump system can reduce the area possessed by the coil, balance annual thermal loads of the geothermal heat exchangers. It could also lighten the tension of the power supply and balance the on and off-peak electric load of the power grid. It will be a kind of energy saving and clean air conditioning mode for the buildings in the 21st century.