Simulation and optimization of air conditioning and ventilation system in an urban train passenger room

Taking the air conditioning and ventilation system for a passenger room in an urban train as the research object,this paper presents a new simulation model which combines the passenger room,supply air system,return air system,exhaust air system and outdoor air system,and makes the simulation boundary conditions fit the actual project.By using ANSYS Fluent software,the air distribution and heat transfer of air conditioning and ventilation system in the urban train are simulated and optimized.The results show that the return air volume of four return air outlets of two air conditioning units before optimization is 0.24,0.26,0.35,0.19 kg/s,respectively,and the distribution of return air volume is not uniform.The exhaust air duct is too narrow,resulting in the exhaust air system resistance up to 629 Pa.In view of this,the return air structure and exhaust air structure of the passenger room are optimized.After optimization,the difference between the maximum and minimum return air volume is only 0.05 kg/s,and the flow resistance from the passenger room to the exhaust air outlet is reduced to 120 Pa.The temperature range of most areas in the passenger room is 24 to 26 ℃,and the main activity range of the personnel inside the passenger room is at the breeze speed,and the comfort is significantly improved.This study can provide a basis for the optimal design of the air conditioning and ventilation system for urban trains.