Theoretical And Experimental Research On Geothermal Heat Exchanger In The Integrated Soil Cool Thermal Storage And Ground Source Heat Pump System Under Coupled Heat Conduction And Groundwater Advection

For utilizing the renewable ground thermal energy, the ground source heat pump system(GSHP) is taken as an air conditioning technique which has the greatest developmental future, energy saving and environmental protection advantages in the 21st century. As we all know, the heat transfer of geothermal heat exchanger (GHE) is affected by a lot of factors, where groundwater advection has a comparatively great impact indicated by experimental data. While almost all the design tools for GHE are based on principles of heat conduction and rely on some estimate of the ground thermal conductivity and volumetric specific heat. However, the large part of vertical U-type pipe lies in the saturated soil, especially in zones along the coast or with plentiful groundwater, which will be affected by groundwater advection greatly. At that time, there happens transient, complicated coupled heat conduction and groundwater heat advection in the saturated soil. Furthermore, both current in-situ conductivity test data interpretation methods and GSHP design methods are based on models that only consider heat conduction. Therefore, the groundwater flow may impact the results of in-situ thermal property of soil, and then the GHE size, and make the short-time economics of GSHP comparatively unattractive consequently.Moreover, for purpose of solving the unbalance cooling loads in summer and heating loads in winter, the tension of the power supply and balance of on and off-peak electric load in Hot Summer and Cold Winter Zone, the integrated system of soil cool thermal storage and ground source heat pump (ISCTS&GSHP) is presented. The advantages of the cool thermal storage and GSHP are fully utilized in the system, and the underground heat exchangers of the GSHP are also served as the ice storage equipments at one time. Using the electric power during nighttime (off-peak period), the cooling load is stored on the underground soil partially or fully to satisfy the air conditioning load requirement during daytime (on-peak period).Based on the above, the theoretical and experimental researches on the performance of GHE under coupled heat conduction and heat advection are implemented in this paper.