Study On The Heat Transfer Characteristic Of The Capillary Heat Exchanger In Subway Tunnel

In subway tunnel, capillary tubes network heat exchanger is the capillary network laying on the subway tunnel wall, as the front of the heat exchanger in heat pump system. The capillary tube heat exchanger in the subway tunnel can use the cold and heat energy in the natural superficial layer to cool the subway platform in summer and heat the ground building in winter, which can achieve the purpose of energy saving and environment protection.In this paper, the heat transfer characteristics of the capillary tube heat exchanger are analyzed start from heat exchange. Combined heat pump system operation and regulation, study the influence of the capillary tube heat exchanger’s tube spacing, tube velocity and length of tube to heat exchange. The main research contents are as follows:1、Analyze heat transfer of the capillary tube heat exchanger in the subway tunnel. In view of the subway tunnel environment, the heat transfer mechanism of subway surrounding rock is analyzed, and the heat transfer model of tunnel surrounding rock is established. Numerical simulation is carried out to obtain the heat transfer law of subway surrounding rock mass.2、Heat transfer experiment of capillary tube heat exchanger is carried out to analyze the heat transfer law and characteristics of heat transfer. Numerical simulation is carried out for the experimental conditions, and the results are compared with the experimental results.3、Numerical simulation analysis of the actual conditions of the application of the capillary tube heat exchanger in the subway tunnel is carried out. According to the analysis results, the one by one analysis of capillary tube flow rate, capillary tube spacing and capillary tube length three factors of subway tunnel capillary for heat exchanger for heat and heat pump system operation regulation effect.4、Comprehensive analysis of capillary for flow velocity within heat exchanger tubes, tube spacing and length of subway tunnel capillary heat exchanger heat and regulate the operation of the heat pump system. Obtain the suitable range or calculation method of capillary tube flow rate, capillary tube spacing and capillary tube length of capillary tube heat exchanger, when it is installed in subway tunnel wall.5、According to the practical engineering case, introduce the subway tunnel capillary heat exchanger tube flow rate, pipe spacing and length determination method.This paper through heat transfer experiment of capillary tube heat exchanger and numerical simulation calculation method, analyzed the basic law of heat transfer and the characteristics of heat transfer in capillary tube heat exchanger. Study on the effect of capillary tube flow rate, pipe spacing and length to the capillary heat transfer. Provide theoretical basis for the application and popularization of the capillary heat exchanger in tunnel.