Study On Airflow Distributing Characteristic And Thermal Comfort In Pure Electric Bus

In order to deal with energy shortage and environmental pollution,China is vigorously developing new energy city bus in the field of public transport.People spend more and more time in the bus,the comfort of the bus has become a growing concern.Thermal comfort has a direct impact on the physical and mental health of occupants,driving safety and fuel economy.Therefore,the research of thermal comfort in the bus is very important to automobile companies.At present,there are two main methods in the study of thermal comfort,which are thermal comfort test and numerical simulation.To accelerate the development cycle and reduce development cost,the method of Computational Fluid Dynamics(CFD)is widely used in automobile design and development.In this paper,CFD is used to study the distribution of air-flow and the thermal comfort of human body.The results provide a basis for improving the thermal comfort of the pure electric bus,reducing the energy consumption and optimizing the design of the air conditioning system.According to the body structure and physical properties,the heat load model in steady state is established.The calculation program of heat load is written by MATLAB.This paper analyzes the influence of various parameters on the heat load,and puts forward some methods to reduce the heat load of the carriage.A simplified model of compartment interior is established by the ICEM.Based on the study of the grid independence and turbulence equation,the Realizable k-? model is selected.The velocity field and temperature field are measured by experiment.The simulation results are in good agreement with the experimental data,which verifies the reliability of the numerical simulationThe three models of no-load,full load and overload are calculated by FLUNT,and ten different air supply parameters are calculated under full load model.In the analysis of result,the velocity field and temperature field of many typical sections are extracted by Tecplot,and the data of temperature and velocity along the carriage height(Z-axis)are analyzed.Finally,the effect of the number of passengers and the air supply parameters on the air distribution and thermal comfort is analyzed qualitativel.The calculation results of FLUENT are retrieved,and then do analytic statistics.Several typical sections were selected,and the air distribution was evaluated by the method of nonuniformity coefficient and air diffusion performance index(ADPI);the thermal comfort of human body in different compartments was evaluated by equivalent temperature(EQT);the economic performance of bus air-conditioning system was evaluated by energy utilization factor(input energy utilization coefficient).Finally,according to the results of the previous analysis,I optimized the design of the air conditioning and ventilation system under the condition of constant air supply parameters.,mianly by changing the material of the car glass,the layout of the air outlet,the way of air supply and return.Thermal comfort was improved by the design of multi zone independent control air conditioning system.