Numerical Simulation Of Heat Transfer Process Of Ground Heat Exchanger

Ground source heat pumps as a new environmentally friendly energy-savinggreen air conditioning technology have been widely used and development at homeand abroad. In the vertical ground heat ground source heat pump system, the groundheat exchanger design calculations is the key to efficient operation of the entiresystem and it is the core technology and difficulty of ground source heat pump system.Soil around the ground heat exchanger is porous media which contains gas, liquid andsolid material. The complex thermal properties of the soil are important factoraffecting the heat transfer efficiency, the seepage of groundwater in soil is a key factorwhich is often ignored.There is a problem that the ground heat exchanger was designed too long inactually ground source heat pump project, and it makes the ground source heat pumpproject investment cost increase. Preliminary experience in engineering decision isdue to neglect of groundwater seepage. The heat transfer efficiency of ground heatexchanger is closely related to the arrangement of the pipe group, improper alignmentwill cause heat accumulation phenomenon and may eventually shortened life ofproject. According groundwater flow direction and speed design reasonable pipegroup arrangement can effectively avoid heat accumulation phenomenon and it canimprove heat transfer efficiency. This paper focuses on the consideration ofgroundwater seepage, built underground heat penetration coupled heat exchangermodel. Using FLUENT software for the simulation analysis, and the pipe grouparrangement optimization was discussed. Finally, improved ground heat pipe lengthcalculations and developed ground heat exchanger design calculation software. Themain work of the study are as follows:1. The theory of heat transfer in porous media were analyzed and applied to theactual ground heat exchanger mathematical modeling. A ground heat exchangerthermal penetration coupled numerical heat transfer model was established combinedwith porous media model and turbulence model.2. Using Gambit software to build physical models mesh and using FLUENTsoftware for ground heat exchanger heat transfer simulation. Analysis of the effect ofthe groundwater heat transfer and discusses the relation between the different flow speed and efficiency of the heat exchanger.3. The pipe group numerical heat transfer model was established on the basis ofsingle ground heat pipe heat transfer model. By comparing different groundwater flowvelocity, flow direction and management of different groups in different arrangementmethod, tube group heat transfer efficiency under different conditions of tube spacing,summed up the optimization of pipe group arrangement.4. Under consideration of groundwater flow and thermal interference betweenthe pipes, a method of calculating ground heat exchanger’ length was improved. Anda pipe length design calculation software was developed based on the new calculationmethod.