Design And Numerical Analysis Of Rail Vehicle Heating Device Based On Graphene

In recent years,many large cities in China have opened subway lines in order to facilitate public travel.At present,the heating mode of underground vehicles in China is mainly preheated by air conditioning,supplemented by compensated electric heater heating.The disadvantages of heating in this way are:slow heating of the trainriage,uneven temperature distribution,poor thermal comfort,and large power consumption of the entire heating system,which does not meet the concept of low-trainbon environmental protection.Aiming at the problems existing in the current subway heating system,a set of B-type subway vehicle heating system is designed based on the graphene heating wire.Firstly,the heating capacity of the passenger compartment and the driver compartment of the subway vehicle in winter is calculated respectively,and the design scheme of the graphene heating system is given.The internal flow field model of the subway passenger train room and the driver’s room is established,and the heating effect of the above heating device is numerically simulated to determine the best heating scheme.The heating effect of the subway trainriage under different external air temperatures（-15℃,-10℃,-5℃,0℃,5℃）and the heating rate when the external air temperature is-5℃;then,the temperature distribution of each structure of the heating device using ordinary coating and graphene coating was compared and analyzed.In addition,the air quality of subway trainriages heated by graphene heating system and air conditioning system is compared respectively,and the influence of heating system on air quality is analyzed.According to the calculation,the heating power required for the subway compartment is9.454 k W,and the heating capacity required for the cab is 0.671 k W.Based on above,four new heating devices are designed based on the graphene heating wire with a specification of230W/12.5m as the heating element,Including graphene heating device I and graphene heating device II suitable for passenger compartment,and graphene heating device III for driver compartment,a seat heating system for rail vehicle driver compartment.The simulation results indicate that the heating effect in the trainriage is the best when the graphene heating device I and the graphene heating device II are heated together,and with the decrease of the external air temperature,the heating temperature in the trainriage fluctuates in a small range,but even when the external air temperature is-15℃,it can still meet the heating demand;when the external air temperature is-5℃,the heating system will increase the temperature of the trainriage from 7℃to 20℃only 180 seconds;when the heating device works,the temperature of each structure of the heating device using graphene coating is lower,the heat dissipation effect is better,and the average reduction is about 3℃.There is no significant difference in the impact of graphene heating system and air conditioning heating system on air quality.The data of various parameters（relative humidity,CO₂ concentration,air age）measuring air quality are basically the same.