Simulation And Analysis Of Heat Pipe Heat Exchanger Application In High Speed Train Air Conditioning System

In some parts of China,the external climatic conditions of the winter and summer compartments are relatively extreme.After the fresh air is processed by the air-conditioning system and enters the compartment,it will inevitably bring more pressure to the train air-conditioner.At the same time,a large number of air-conditioning-treated return air is directly discharged after experiencing the inner cycle of the compartment,which will also waste more electric energy.The heat pipe heat exchanger is compact,efficient and cheap,and can independently recover the waste heat of air conditioning return air without external energy supply.The temperature difference between return air and fresh air can sometimes reach more than 20?.Installing heat pipe heat exchanger into the air conditioning system of high-speed train can not only pretreat fresh air,but also improve the thermal comfort inside the compartments.Taking the second-class compartments of a certain type of motor vehicle as an example,the heat pipe heat exchanger is applied to the air conditioning of high-speed train to form a combined system of heat pipe and air conditioner.Firstly,the structure of heat pipe and heat pipe heat exchanger is designed according to the working conditions,and the heat pipe heat exchanger-air conditioning system is integrated with the train compartments.In order to verify the energy-saving effect of heat pipe heat exchanger,the temperature field in the carriage before and after installation of heat pipe heat exchanger was simulated numerically.Finally,the thermal comfort of the compartments in several representative environments is simulated and analyzed,and the thermal comfort of the compartments in different climate conditions is studied.The research shows that the installation of heat pipe heat exchanger has little influence on the flow field in the carriage and can be neglected.By comparing the temperature distribution in the compartment before and after the installation of heat pipe heat exchanger,after installing heat pipe heat exchanger under winter conditions,the temperature of low temperature fresh air can be increased by 6 0C and then entered the train air conditioning system.The highest temperature in the compartment can be increased by 4.86 ?,and the lowest temperature can be increased by 3.5?.Under summer conditions,the high temperature fresh air temperature can be lowered by 3.8?,the compartment temperature is lowered by 2.5?.And the heat pipe heat exchanger is in winter and summer has a good work efficiency.Under the winter conditions,the per capita fresh air volume increased by 6.5m3/h.The preheating effect is reduced by about 0.4?,the temperature inside the compartment is decreased by 1.2 ?,the ambient temperature is increased by 5 ?,the preheating effect is decreased by about 0.6?,the temperature inside the compartment is increased by about 3?;in summer conditions,the per capita fresh air volume is increased by 6.5 m3/h,the pre-cooling effect is reduced by 0.5?,and the ambient temperature is increased by 5?,and the pre-cooling effect is increased by about 0.65?.In winter and summer conditions,the installation of heat pipe heat exchangers will have a positive impact on the thermal comfort of the compartment.The increase in air supply speed will enhance the hair sensation and the mean age of air,but the PMV and PPD indicators are inconsistent with the wind speed.The ambient temperature rises will reduce the hair sensation,and the PMV and PPD indicators will increase.