Optimization Of Air Supply Mode Of Automobile Air Conditioning Based On Thermal Comfort Of Passenger Cabin Environment

With the rapid development of the automotive industry and the increasing demand for cars,consumers’ requirements for cars are getting higher and higher.People are no longer just satisfied with the convenience and speed of cars,but also pay more and more attention to the comfort of the space inside the car.Due to change in external solar radiation,wind speed,vehicle speed,air humidity,temperature and other environmental parameters will also change significantly,to keep the parameters inside the car stable in the range of human thermal comfort,the automotive air conditioning system plays a very important role.The principle of automotive air conditioning systems is to improve the comfort of the passenger compartment through heating,cooling and dehumidification,thus ensuring a good thermal environment for the passenger compartment,while the improvement of the air conditioning system needs to be based on the subjective feelings of people.The development and current status of thermal comfort research at home and abroad are firstly described,followed by a detailed introduction of the definition and application of equivalent space temperature and related solution methods,an introduction to thermal sensory evaluation methods,and the establishment of a thermal comfort evaluation method suitable for Chinese people.To construct this thermal comfort evaluation method,the relationship between equivalent space temperature and thermal sensation was obtained by collecting thermal sensation data from human bodies in different environments.An evaluation method based on the whole-body and local thermal sensory characteristics of adult Chinese men and women was designed.The local and whole-body equivalent space temperatures of the passenger seat were tested using a warm body dummy to predict the whole-body and local thermal sensation values of the passenger seat.Under the same conditions,local and whole-body thermal sensations were tested using the subjective experience of the subjects.The predicted thermal sensation obtained through the equivalent space temperature was compared to the subjective experience results,and the correlation reached up to 0.911,while significance(two-tailed)reached 0.002,it was possible to predict the thermal sensation vote within an accuracy level of 0.3 point,further proving the accuracy of the whole-body and local thermal comfort evaluation method suitable for the Chinese population as proposed in this paper.The thermal sensory evaluation method suitable for the Chinese population and the digital dummy model reflecting human thermal comfort are then applied to FLUENT simulation and computation to evaluate the thermal comfort of passengers under the same environmental conditions as the subjective and objective experiments.Analysis by flow field distribution etc.reveals that the overall thermal comfort is good,but the front passengers’ feet and legs feel hotter and the blowing sensation near the face and chest is too strong;while the rear passengers have a poorer blowing sensation and a relatively worse thermal sensation.By comparing the simulation results with the equivalent space temperature results of the warm dummy,it was found that the two have high similarity and the digital dummy can be used to replace the warm dummy for the equivalent space temperature measurement.Finally,the air supply angle,air velocity and air temperature of the air supply outlet in the passenger compartment are optimised using simulation,providing a direction for optimising the human thermal sensation in the passenger compartment.