Study Of Effect Of Groud Water Seepage On Characteristics Of Heat Transfer In Ground Source Heat Pump Systems

The Ground Source Heat Pump(GSHP), a highly efficient , energy-saving air conditioning, is helpful for environmental protection and sustainable development. The GSHP technology has brought opportunities to solve the energy crisis, the pollution problem and sustainable development of china. The technology has a beautiful future in China. The applied research of GSHP involves the hydrological and geological condition in the shallow layer earth. The property of soil is an important factor of the operation characteristics of GSHP. But seen from ground water seepage in the fundamental researches and the actual projects, it has a significant influence on the operation characteristics of GSHP. So it is the determining factor of the accurate design of GSHP.First this thesis elaborated the characteristic of the GSHP, the present situation and the progress of researches on the GSHP, and the property of soil related to the GSHP system. Then on the basis of the hydrological and geological condition in Chengdu plain, saturated porous medium considering ground water seepage was assumed to set up model of the well group and the coupled thermal conduction, and the ground water seepage model of underground temperature field around the well group. The heat transfer between the well group and soil, and the soil temperature field was simulated. The GAMBIT was used to constitute physical model, and the Fluent software was used to conduct the numerical simulation. Large-scale experiments were carried out in a GSHP test-bed provided by Southwest Jiaotong university to verify the simulation model.This thesis analyzes the effect of different soil properties, such as thermal conductivity,specific heat,density,porosity, groundwater seepage velocity and heat exchange quantity on temperature field. Base on the temperature field, the optimization method of well group arrangement to avoid thermal interference among wells and to reduce occupied area, and the evaluation standard of the optimization arrangement of wells, were pointed out. After that, it propose the new method to predict length of the buried pipes in the underground water seepage domain.Finally, two operation methods of the GSHP system under partially load were compared, and the conclusion can be drawn that the operation method of small-load continuous operation is preferred.