Analysis And Optimization On Thermal Comfort Of Vehicle Cabin

Automobile has become an indispensable tool in people's daily life,playing an significant role in the fields of transportation,tourism,entertainment and so on.With the vigorous development of the global auto industry in recent years,it has been in an increasingly urgent demand to enhance the thermal comfort of vehicle passenger compartment.Under the policy of energy conservation and emissions reduction proposed by our country,how to balance the thermal comfort of passengers and energy-saving properties has become a new research direction of the vehicle.Passenger compartment has a complex internal structure and narrow space,characterized by the heterogeneous and dynamic changes of environmental parameters,so it has always been the research challenge for native scholars and abroad to establish the transient thermal environment evaluation indexes.Many foreign scholars develop numerous evaluation indexes for non-uniform thermal environment based on establishing the uniform thermal environment evaluation indexes to evaluate the vehicle interior thermal environment.Domestic researchers use CFD to simulate and analyze the flow field in passenger compartment by means of the existing reasonable evaluation index,considering of the external factors,thus optimizing the thermal environment to achieve the purpose of improving occupant thermal comfort.Firstly,on the basis of the method of computational fluid dynamics and heat transfer theories,the structure of the vehicle geometric mode is simplified to establish the mesh model.Set the corresponding boundary conditions in considering of the influence of car body heat transfer and solar radiation,invoke the human body thermal comfort model(TCM Module),and the passenger cabin thermal comfort simulation model is set up.Comparing the simulation results with cabin air conditioning cooling experiment,the error of the detective point temperature is calculated which is within 10%,the simulation model can meet the requirements of engineering calculation and its accuracy is verified as well.Comparing the advantages and disadvantages of different thermal comfort evaluation index,the equivalent temperature(EQT)and overall thermal comfort deviation(AEQT)are applied as evaluation indexes,and cooling load(P)is applied as the energy-saving index of different air supply schemes.Select several parameters of air supply as twelve simulation conditions,analyze the temperature and flow field distribution on different observation section,and set some simplified observation points to get the information of surrounding temperature and air velocity,it studied the influence of supply air temperature,flow flux,and the angle on the interior heat flow field distribution,the thermal comfort of passenger and the cooling load.It optimizes the combinations of supply air parameters by analyzing the effect of different parameters on interior thermal comfort and energy saving properties.Use the response surface method to operate a multi-objective optimization on the heat flow field simulation model of vehicle cabin.Set up the functional relationship of AEQT and P with four design parameters that are supply air temperature,air speed,Y and Z angle.Calculate the corresponding response values of sample points in the thermal comfort model,and fit the regression equation of the target parameters and the design variables,using the response surface method to analyze the influence of the designed parameters on the designed goals,and get the optimal parameter combination.Comparing the prediction data of designed target with the simulation value,the feasibility of the optimization method is verified.The research and optimization method of thermal comfort in this paper provides a thought of balance thermal comfort and energy-saving properties.This method will be a reference to the study on air conditioning supply automatic control.