Numerical Analysis And Application Of Heat Transfer In Deep Hole Coaxial Tube Ground Heat Exchanger

Ground source heat pump(GSHP)system has been widely promoted and applied in recent years as an efficient and energy-saving system using geothermal energy as a cold and heat source.Compared with the widely used shallow hole buried tube heat exchanger,the deep hole tube type ground heat exchanger has the advantages of covering less area,well performance in seasonal heat storage and winter heat exchange,so that it is more suitable for winter heating supporting in cold areas in the north like the north part of China.As the result,the deep hole tube type ground heat exchanger has attracted attracts wide attention.However,The heat transfer effect between the deep hole tube type ground heat exchanger and the underground rock stratum plays a vital role in the operation performance of the heating system.In view of the relatively few research on about the deep hole tube type ground heat exchanger,this paper will focus focuses on the heat transfer performance of the deep hole tube type ground heat exchanger in the cold region;the north part of China.The underground heat transfer process of deep hole tube type ground heat exchanger is more very complicated,complex and also there are many kinds of The factors which will influence the heat transfer performance.are also more,for the reason that the underground heat transfer process of deep hole tube type ground heat exchanger is more complex.In this paper,a numerical model based on the finite difference method is selected as the research basis.The numerical model uses the alternating difference calculation method innovatively,which not only reduces the time consumed by the model in spent in the calculation process,but also ensures the accuracy of the model calculation results.First,determine the boundary conditions of the numerical solution model are determined,and then compare the data from the numerical solution model with analytical solution modeland the data in other literature under certain conditions,which proves the rationality and accuracy of the numerical solution model.The distribution of underground temperature field is simulated after three months of continuous heat acquisition,and the thermal interference radius of a single deep borehole is determined.Secondly,the concept of give the definition of "nominal heat capacity of deep hole tube type ground heat exchanger",and analyze the influence of flow direction,flow velocity,heat resistance of pipe wall inside and outside and pipe diameter on heat exchange performance of heat exchanger,address suggestions on about optimizing heat exchange performance of heat exchanger.At last,In the end take a building in cold region of the northern China as an example,simulate the temperature change trend of different working conditions,and discuss the effect of seasonal heat storage.According to the different actual situations,different heating operation schemes will put forward in the condition of no seasonal heat storage.In this paper,a reasonable numerical model is used to study the heat transfer performance and the law rule of heat transfer in the deep hole tube type ground heat exchanger,draw some conclusions on the optimization of heat exchanger heat transfer performance,and puts forward the different heating scheme,and discuss how to get better in practical construction of deep hole tube type ground heat exchanger has a certain guiding role bushing.