Structure Optimization And Design Of Bus Air Conditioning Duct

In recent years,with the rise and rapid development of urban public transport,the number of public transport operators has increased.Because the structure of the air-conditioning ventilation duct and the layout of the air outlet are too simple or unreasonable,there are problems such as uneven distribution of air-conditioning outlets in the air-conditioned bus passengers in China.The temperature difference between the front and the rear of the vehicle is usually higher than 5 degrees Celsius.Affect the ride comfort of the occupants in the car.Due to the uneven distribution of passenger density in the front and rear passenger compartments of passenger cars,the demand for cooling airflow is different.To this end,this paper takes a domestic bus as the research object,and uses the fluid simulation software STAR-CCM+ as a tool to obtain the internal flow field and temperature field distribution of the bus by simulation,taking the temperature around the passenger and passenger comfort as the evaluation index.The optimization of the air conditioning duct and outlet of the model and the improvement of passenger thermal comfort were studied.Firstly,the background and research significance of the research on the optimization design of air conditioning ducts for passenger cars,the necessity of research,the research history,current situation and current research shortages of scholars and experts at home and abroad are expounded.Then the theoretical basis of fluid simulation and CFD simulation are introduced.The process introduces the theoretical basis of heat transfer;discusses the selection of physical models and the setting of boundary conditions for different parts of the body,and the division of the surface mesh when the bus and the temperature field are simulated.The body mesh scheme,etc.;introduces the principle and setting of the solar radiation model and the human body temperature regulation model;finally,the basic working condition of the air supply temperature of 15 degrees Celsius,the total air supply flow rate is 1kg/s,and the internal flow field of the bus Analysis of the temperature distribution revealed that the main contradiction was that the temperature distributionaround the passengers in the car was uneven.After investigation,it is finally determined that the overall direction of air conditioning optimization is the optimization of the air outlet position and the air duct.According to the influence of the air volume and the air supply temperature on the temperature field distribution in the vehicle,different working conditions are designed.Since the air conditioning air outlet is close to the front of the passenger compartment,due to the far distance from the rear,the air traffic duct flow resistance affects the rear passenger.The cooling airflow of the air supply port is smaller than the front.And the rear passengers themselves are more in number than the front,that is,there are more heat sources,so the temperature is higher,showing the problem of longitudinal temperature unevenness in the cabin,and more cooling airflow is needed in the rear,which is the key point of optimization.According to the lateral temperature field distribution,the lateral temperature field in the passenger compartment is not uniform due to the lack of oblique air outlets.Finally,combined with the temperature distribution of the passenger's head,due to the total air supply volume of the air conditioner of 1.2kg / s,the supply air temperature of 15 °C,most of the passengers in the front and middle are basically close to the human body comfort temperature,and finally determined on this basis The optimization of the position and structure of the air supply vents and air ducts under working conditions provides a basis for the optimization of air conditioning vents and air supply temperatures.The main problem is that there are more people in the rear passenger compartment and insufficient cooling airflow.On the basis of the basic working conditions,the scheme of increasing the passenger air supply port in the rear row,adding the reverse flow plate in the air duct,and removing the reinforcing ribs in the air duct respectively is adopted to solve the problem of temperature unevenness in the lateral direction of the cabin,and increase in the rear part of the passenger compartment.The diagonal passenger air vents improve temperature uniformity and improve ride comfort.