| Increasing the speed of trains is an important issue in the reform and development of China’s railways.However,due to air resistance,when the speed of high-speed vehicles in the atmospheric environment exceeds 400 km/h,the economic benefits will be greatly reduced.The vacuum tube train is a new mode of transportation created to overcome air resistance.Its train can travel at ultra-high speed in a near-vacuum tube,which is an important development direction of green,energy-saving and ultra-high-speed rail transportation technology in the future.However,the near-vacuum operating environment limits the use of traditional airconditioning systems on vacuum tube trains.The research on the internal environment control system of the vacuum tube train can provide a method and basis for overcoming the above problems,which is of great significance to the research and development of the vacuum tube transportation system.This thesis first analyzes the operating environment and vehicle characteristics of the vacuum tube train,and proposes an environmental control system suitable for the vacuum tube train based on the existing closed space environmental control technology.Among them,the temperature control system is based on the principle of ice storage and melting,and the air in the train is introduced into the ice storage device installed on the train for cooling.At the same time,a variable air volume box is set at the end of the system to adjust the cooling air volume to ensure thermal comfort in the train.The oxygen supply method adopts high-pressure gaseous oxygen for oxygen supply,and carbon dioxide is treated by soda lime absorption method or lithium hydroxide absorption method.Then,the key equipment and parameters of the internal environment control system of the vacuum tube train are calculated and analyzed,the equipment forms of the ice storage device,the variable air volume box,the high-pressure gas storage tank and the carbon dioxide treatment device are determined,and a method for theoretical calculation of related parameters is proposed.Then,based on the theory of flow and heat transfer,a numerical calculation model of one-dimensional AMESim and three-dimensional CFD co-simulation was established for the temperature control system based on melting ice,and the effect of variable air volume temperature control system was analyzed.The influence of the thickness,length of the ice storage plate and the width of the air duct between the plates on the cooling performance and energy consumption of the system was also studied.The research results show that the variable air volume can greatly increase the temperature control time of the ice melting heat exchange equipment and improve the cooling capacity of the ice melting heat exchange equipment.Reducing the thickness of the ice storage plate can not only significantly prolong the temperature control time of the melting ice heat exchange equipment,but also reduce the energy consumption of the system,which is the most economical and effective way to optimize the effective control time of the refrigeration system.Although increasing the length of the ice storage plate and reducing the width of the air duct between the plates can increase the temperature control time of the ice melting heat exchange equipment,the effect is not significant and it consumes more energy.Finally,with the help of numerical simulation method,the optimization research on the interior environment and airflow organization of the vacuum tube train based on the icemelting variable air volume refrigeration system is carried out.The research results show that the change of the primary return air volume of the internal environment control system of the vacuum tube train has little effect on the internal temperature and carbon dioxide distribution.The internal environmental control system of the vacuum tube train can meet the passenger’s needs for temperature,carbon dioxide concentration and oxygen supply.The upper-feed and upper-return airflow organization is more suitable for application in the environmental control of the vacuum tube train than the upper-feed and lower-return airflow organization. |
