Research On Prediction Model Of Thermal Environment Of Metro Capillary Heat Pump

In order to solve the traffic congestion caused by the increase of the population of the big cities in China,the subway has developed vigorously because of its unique advantages.However,the subway has improved the traffic at the same time,and it has brought great problems.After the long-term operation,the subway tunnel thermal environment gradually Deterioration,the phenomenon of heat accumulation.Therefore,it is very important to analyze the causes of heat accumulation in subway tunnels,master the factors that affect the thermal environment of tunnels,and take effective cooling measures.In this paper,the capillary heat exchanger is embedded in the surrounding rock of the subway tunnel to form a subway capillary heat pump temperature drop system.The capillary heat pump thermal environment prediction model is established by analyzing the heat transfer mechanism between the capillary heat exchanger,the surrounding rock and the air inside the tunnel.The evolution law of temperature field of tunnel surrounding rock is of great practical significance to the thermal environment control of subway tunnel.The main contents of this paper are as follows:Firstly,the heat transfer characteristics of subway capillary heat pump thermal environment are analyzed.Considering the third kind of nonhomogeneous boundary conditions and the heat transfer effect of capillary heat exchanger,the theoretical model of metro capillary heat pump heat transfer is established.Secondly,the temperature field is simplified as the boundary condition term,the initial condition term and the internal heat source by rationally simplifying the influencing factors of heat transfer.The analytical solution of the constant air temperature is obtained by using the Green's function,Laplace function and Bessel function.Air temperature theory,the analytical solution of capillary heat pump heat transfer model with time variation of tunnel temperature is obtained.Based on the field experiment of subway capillary heat pump system in subway tunnel,the change of outlet temperature and running time under different working conditions is obtained.The analytical solution of capillary outlet temperature is calculated by Matlab software and compared with experimental data.Verify the correctness of the heat transfer model;Finally,according to the results of the heat transfer of the metro capillary heat exchanger,the physical model of fluent heat pump is used to simulate the capillary heat pump system.The correctness of the heat transfer model is verified by the theoretical analysis of the model.Based on the analytical solution model,The thermal conductivity,the thermal conductivity of the surrounding rock,the heat capacity of the surrounding rock,the heat flux and the operation mode are analyzed and analyzed.Finally,some conclusions and suggestions are obtained.