Air Quality Evaluation And Optimization Control Technology In Vehicle Cabin

There are symptoms of sick air conditioning syndrome in coach,such as dizziness,fatigue and nausea,and the incidence is high.The air pollution in the coach is serious and the air quality in the coach is bad.Therefore,this paper selected the coach with dense personnel as the research object,evaluated the air quality in the coach and studies the optimal control technology of the main pollutants in the bus.Firstly,selecting 4 coaches that the age is less than 2 years,detecting the main parameters(temperature,relative humidity,wind speed,formaldehyde,carbon dioxide,TVOC,PM_2.5)of air environment.And,the subjective questionnaires were sent to the passengers to see their actual feeling for air quality of coaches.Secondly,the grey correlation analysis method was used to evaluate the air quality of the 4coaches to obtain these coaches'air pollution level.Then,analyzing the relationship between the datas of objective measured parameters and the subjective evaluation by grey correlation analysis method to obtain the main factors that cause the passengers'physical discomfort.Finally,on the basis of the previous research results,FLUENT was used to simulate the distribution of main pollutants in coach.By comparing the concentration changes of the target pollutants under different simulation schemes,the control measures for the air quality in coaches were obtained.Research shows:.?1?the overall heat and humidity environment and the concentration level of formaldehyde in the 4 coaches meet the requirements;compared to GB/T17729-1999,the exceeding standard rate of CO₂ is 100%;the concentration level of the PM_2.5.5 in the sample 2 is excessive;except for the sample coach 3,the concentration of TVOC in all vehicles are excessive.?2?over 80%passengers are satisfied with the heat environment of the coaches;but more than 20%of the passengers are dissatisfied with the air quality in the coaches;at the same time,the passengers have conditioned syndrome of air conditioning in the coaches,including fatigue,dizziness and nausea.?3?the grey correlation analysis method is used to evaluate the 4 coaches,of which sample 1 and 2 are heavy pollution,sample 4 is light pollution,and sample 3 is no pollution.The main discomfort symptoms of the passenger about the sick air conditioning syndrome were correlated with the environmental related parameters.It was concluded that TVOC and CO₂ were the main factors that caused the passengers'adverse reactions in the 4 coaches.?4?the concentration distribution and optimization of TVOC and CO₂ in the coach are carried out numerical simulation by using FLUENT.With CO₂ as the representative pollutant,find that when air supply velocity is 4 m/s,supply air ngle is15°and the new air volume is 35 m³/h,the concentration of CO₂ can be diluted below the national standard and meet the needs of the human body for it.On the basis of the optimization results of CO₂,the concentration distribution of TVOC is predicted.It is find that the effect of TVOC'concentration distribution is good in the passenger breathing area when the size of the air outlet is expanded to100mm×700mm and the air inlets are added in the coach'before and after.,the concentration is reaches the national standard when the concentration level is0.52mg/m³.