Study On Cooling Characteristics Of Hot-soak Precooling Ventilation And Personalized Air Conditioning For Passenger Car

Summer car parking,in the role of solar radiation,the car room temperature rises suddenly will make people unbearable,while the car interior in the high temperature volatile harmful substances will cause great harm to the human body,but at this time,opening the air conditioning immediately will make the engine run at high load,cause waste of resources and engine damage.The direct use of traditional air conditioning in urban traffic with only one driver will cause a great waste of energy.Therefore,in order to solve the problem of high temperature in the passenger compartment and the problem of energy consumption after air conditioning opening,it is of great significance to study the pre-cooling ventilation scheme when parking and explore the personalized air conditioning delivery mode to balance the contradiction between thermal comfort and energy saving.In this paper,according to the thermal environment problems after hot-soak and the limitations of thermal comfort of traditional air conditioning,the basic theories of computational fluid dynamics and heat transfer were used to analyze the characteristics of hot immersion effect in passenger compartment by using CFD numerical simulation method.The new mode of top pre-cooling ventilation and personalized air conditioning was adopted to conduct pre-cooling ventilation and cooling during parking,so that the temperature was close to the ambient temperature.The personalized air conditioning and cooling were carried out after the driver enters the passenger compartment,which can not only ensure the comfort of the driver,but also save energy.The main work and results of this paper were as follows.1.Established the geometric model of the cabin,completed the meshing and boundary conditions.the numerical simulation of the hot-soak effect of the established model was carried out,and the experimental method was used to verify the reasonableness of this model,and the error is within 10%,which meets the engineering design requirements.2.For the summer occupant compartment heat soak problem,the transient calculation of the 14-hour occupant compartment thermal environment was used to analyze its temperature distribution,and the effect of heat soak effect was studied by changing the glass and seat material parameters and selecting different parking methods.The maximum wall temperature can be reduced by 7.3℃ for every 0.2decrease in glass transmittance and 5℃ for every 0.2 decrease in seat absorption.At different time periods,choosing the appropriate parking method can make the seat wall achieve an effective cooling of 22℃.3.Aim at the thermal environment problem before the driver enters the cabin,the pre-cooling ventilation mode was used to simulate four top ventilation solutions,all of which can reduce the air temperature in the passenger compartment to close to the ambient temperature in about 10 minutes,and also improve the air freshness of the ride space,among which the solution with the air inlet and outlet vents arranged longitudinally in the roof position has a cooling effect of about 12℃ on the seat wall directly contacted by the driver,and the cooling rate was the optimal,which can effectively improve the comfort of the passenger cabin.4.To address the issue of thermal comfort in the passenger compartment containing only the driver,firstly,according to the equivalent temperature Teq and the overall thermal sensation deviation AEQT evaluation index,the shortcomings of the driver thermal comfort of traditional air conditioning were analyzed,and personalized air conditioning ventilation mode for the driver was proposed to evaluate the driver thermal comfort under single and mixed air supply modes.Secondly,comparing the thermal comfort effect of hybrid ventilation mode under different parking modes and verifying the effect with weighted PMV value,it is found that the hybrid air supply mode can better meet the thermal comfort of drivers in different parking modes;finally,the cooling capacity is calculated for the hybrid ventilation mode of traditional air conditioning and personalized air conditioning,and the results show that compared with traditional air conditioning,the hybrid ventilation mode of personalized air conditioning can ensure the overall thermal comfort of drivers in The result shows that compared with the traditional air conditioning,the personalized air conditioning hybrid ventilation mode can ensure the driver’s overall thermal comfort is improved by 30.1% and the energy-saving effect is improved by 37.98%.