Affect Of Underground Pipe Group's Surround Soil Temperature By Heat Flux And Soil Moisture

Underground pipe heat exchanger is the most common heat exchanger in ground source heat pump. The heat transfer performance of underground pipe is the main factor which affects the efficiency of ground source heat pump. Researches of single underground pipe home and aboard are relatively complete, but researches aims at pipe group are still at the primary stage. The heat transfer performance of underground pipe group are influenced by many parameters such as arrangement forms, pipe depth, ground load and soil heat transfer coefficient & etc. In order to ensure the normal effect and long-term use of underground heat pump, further study of pipe group's heat transfer is necessary.Through the non-steady-state analysis of underground pipe group heat exchanger and according to its running characteristics, we adopted limited long-term heat source model and the superposition principle which prier to traditional unlimited long-term heat source model during the numerical modeling. The model could described one dimensional temperature field on the depth direction and two dimensional temperature field on the horizontal direction. Through programming the model by numerical simulation software MATLAB, pipe group's surrounding soil temperature changers of any moment or radius could be simulated under different soil heat transfer coefficient.According to the limited long-term heat source model, we established test platform to make experiment about temperature changes of underground pipe group's surrounding soil. The temperature field of the surrounding soil which influenced by different heat flux and soil moisture was validated and analyzed under summer conditions. Every error ranges of each testing points' experimental data are all smaller than 10% which is within the allowable range. This well validated the accuracy of using limited long-term heat source model during the numerical model establishing.Through changing parameters of the program, we achieved to obtain the simulation analysis and corresponding variation about over more temperature and thermal response time of the underground pipe group's surrounding soil under different heat flux and soil moisture. At the same time, over more temperature and thermal response time would be also varied from the different testing point location. Through analysis and research, this paper will have guidance and suggestions to the future actual projects of the ground source heat pump system.