Optimization On Thermal Environment Of Passenger Compartment Of A Heavy Vehicle

In the early stage of development, heavy duty vehicles to perform the heavy duty vehicle was influenced by the former Soviet Union. More attention was paid to strong power, high reliability, while thermal environment of passenger compartment was ignored. In the Northeast of China, the outdoor environment temperature in winter, the driver’s reaction ability and manipulation ability was affected by the severe environment, and the thermal comfort of passengers was also poor. This paper was based on the experimental method and numerical simulation method, to improve the thermal environment of passenger compartment. The paper mainly studied:Firstly, according to computational fluid dynamics theory, the turbulence model for control equations of calculation and solution in flow field was established on account of mass, momentum and energy conservations. According to heat transfer theory, analysis of heat transfer process in passenger compartment was analyzed simply, including principle of thermal conduction of body wall, the thermal resistance of thermal conduction, convection heat transfer coefficient and other parameters were calculated, then the heat load was obtained under different ambient temperature conditions to content to human thermal comfort, from the point of view of heat, the necessity of designing the heating system for the passenger compartment was described.Secondly, the real vehicle test of heavy duty truck was carried out, the experimental data of the temperature value of the monitoring point in the passenger compartment was obtained, the temperature distribution in passenger compartment was analyzed. At low temperature, passenger compartment temperature is extremely low, which cannot meet the passenger thermal comfort in original heating system. Three-dimensional model was built by CATIA, experimental data obtained in winter environment as boundary conditions of CFD numerical simulation, the experimental and simulation values were compared, to correct the three-dimensional model, so it verified the passenger compartment model was set up reasonable reliability.Thirdly, this paper designed a heating system, when the cooling water temperature was below 76 ℃, the cooling water come from in the tank was heated by fuel heater, when the temperature reached above 85 ℃, cooling water put into two parallel heat exchanger, under the action of the fan, the heated air was blown into the passenger compartment. In order to ensure air heating system was fully utilized, a reasonable duct was designed and the temperature of feet and heads of passengers was improved, to meet the thermal comfort of the passengers.Finally, the new heating system for improvement the thermal environment of passenger compartment were analyzed by the CFD numerical simulation method. Studying on single factor levels of heating system influence on thermal environment of passenger compartment. Analysis by using the orthogonal design theory. The effect of the chamfer radius of the air outlet, the angle between duct axis and X axis, the height of the outlet, the type of return air grille on the thermal environment of passenger compartment were analyzed, The influencing order for thermal environment was the angle between duct axis and X axis> the height of the outlet > the chamfer radius of the air outlet > the type of return air grille. The temperature of heads and feet of driver, passenger 1, passenger 2 were monitored, according to the theory of orthogonal experimental design and selection of structure parameters of heating system, the chamfer radius of the air outlet is 60 mm, the angle between duct axis and X axis is 110°, the height of the outlet is 570 mm, the type of return air grille is Z-6-280×5.Through this paper, the reasonable outlet and return air grille can improve the thermal environment of passenger compartment, at the same time well uniformity of temperature and flow field were obtained. This paper provided a theoretical basis for the improvement of thermal environment of heavy duty vehicle passenger compartment.