A Study On Indoor Flow Field And Thermal Comfort Of A Light Bus

With the improvement of living standard and the popularity of automotive products,people's requirements of car ride comfort are continuing to increase.The thermal comfort and air conditioning energy consumption is determined by the distribution of indoor flow field and temperature field.The study of the thermal comfort evaluation method of the human body and reasonable design of the air supply parameter is significant to improve the ride comfort and explore the energy saving design of the air conditioning system.Based on the resources of the internship company,this paper studied on indoor flow field and thermal comfort of a light bus.The main research contents are as follows:The simulation model of light bus was established.Bus Interior Physical Model was built by using CATIA enveloped the original bus model and adding the driver geometry.Based on the theory of computational fluid dynamics and the characteristics of indoor air flow,a finite volume model of passenger compartment was established by ICEM.The RNG k-? two-equation model was used to simulate the indoor turbulence and the solver,simulation algorithm and relaxation factor were analyzed and selected.The method of calculating the cooling load of air conditioning of light bus based on numerical simulation technology was put forward.Based on the material parameters of bus body and the thermal environment in summer,the influence of solar radiation was calculated by using solar ray tracing model.The indoor environment dynamic thermal balance of the bus was analyzed with considering the leakage of the seal and the heat dissipation of the electrical equipment in the car.According to the law of conservation of energy and the simulation calculation,the matching power of bus air condition is 7216 W.Indoor flow field was analyzed based on human thermal comfort.Based on the prediction average evaluation method(PMV)and the equivalent temperature(EQT),an evaluation method for thermal comfort in the vehicle-thermal comfort deviation evaluation system was established(DEQT).The thermal comfort of the driver was evaluated by three evaluation methods,and the DEQT method was verified.The temperature performance,velocity field and temperature field distribution of the light bus were analyzed.The results show that the design angle of air supply is reasonable,but the airflow of the final cooling air flow near the outlet is short-circuited.The indoor temperature is too high and the thermal comfort is not ideal.The air supply parameters matching were analyzed.The effects of air temperature,velocity,combined air supply parameters and local air supply scheme on indoor flow field and human thermal comfort were analyzed.The results show that the air velocity has a significant influence on the distribution of temperature field and velocity field;the air temperature has obvious effect on the indoor temperature distribution and has little effect on the velocity field;local air can effectively reduce the local temperature and significantly enhance the local area of the occupant thermal comfort.The majority regional air speed was more than 0.5m/s and passengers had a clear sense of wind when increased the cooling capacity only by increasing the air supply rate.At the same power,the scheme of reducing the temperature of air supply was more reasonable in indoor temperature field and the occupant comfort were better.The indoor temperature distribution was reasonable and the thermal comfort of the driver was the best under the scheme of reducing the temperature of air supply combined increasing the local air intake.