Numerical Simulation Of Air Distribution In A Soft Sleeper Compartment Of Air-conditioning Train

With the development of railway and the improvement of people's living standard, air-conditioning train has become the main current in railway passenger car. The problem of comfort in the compartment is increasingly attentioned. The traditional design of the air-conditioning in the compartment is mainly considered only cold or hot as primarily marking in the thermal environment, takes only into account the total quantity of heat transfer and total mass of air flow, thus the distribution of temperature field, velocity field and CO₂ concentration field in the compartment can't be controlled accurately. In this paper, the distribution of temperature field, velocity field and CO₂ concentration field in 25T air-conditioning soft sleeper compartment were studied by numerical method based on different air organization. Based on k ?εturbulent model and Navier-Stokes equation, the finite volume method was used to diseretize the computational domain. In addition, the upwind dieffrencing scheme was used in the computation. And the SIMPLE algorithm was adopted to couple the velocity and pressure. In the calculation, many kinds of heat transfer were taken into account, such as the heat transfer of solar radiation, the heat transfer of walls and body heat. The influence of buoyancy force aroused by temperature difference was also considered.The software FLUENT is used to simulate on different ventilation of 25T soft sleeper compartment. Firstly, the model is simplificated and meshed, then the model of the middle orifice supply air and the two sides sew supply air is bulit, and numerically simulated on different supply air mode. In this paper, the calculation of temperature field, velocity field and CO₂ concentration field is carried out for the different given air parameter based on orifice supply air and sew supply air. In the end, the better parameters of air supply are got. The conclusion is obtained that the better orifice supply air temperature at 18℃and speed at 1.0m/s, and the better sew supply air temperature at 20℃and speed at 2.3m/s. The orifice supply air of soft sleeper compartment can guarantee to get good thermal comfort, which is the better method of supply air. But sew supply air can improve the homogeneous degree of flow field, besides the thermal comfort. On the same total air volume, the sew supply air have the higher supply air temperalure, the better homogeneous degree of temperature field and velocity field, excellent air quality and less energy consumption, which is the better air organization. The experimental measurement is carried out in the soft sleeper compartment of 25T railway passenger car. The data of experimental measurement are coinciding with the simulation results, which verify the reliability of the calculation.