Research On Spatial Distribution Characteristics Of Typical Gaseous Pollutants In Locomotive Cockpit

At present,air-conditioned trains and high-speed trains are at the forefront of travel mode selection.In order to meet the requirements of train speed increase,riding comfort,airtightness and light weight,a large number of lightweight non-metallic materials are used,resulting in an increase in the source of harmful substances and volatile organic compounds(VOC)releases increased,and train air quality decreased.The research on cabin air quality mainly focuses on the design of the air conditioning system,and the research on the VOC content inside the cabin is less.This paper studies the content,influencing factors,release characteristics and spatial distribution of typical gaseous pollutants in the locomotive cockpit.The main research contents include:(1)Use the environmental cabin to explore the analysis of component analysis and content analysis of interior materials under certain experimental conditions during the experimental period.The results show that the interior materials release different types and contents of VOCs,among which TVOC releases the largest amount,followed by benzene,toluene,xylene and other substances.And as the test time progresses,the content of each VOC component released by the experimental material decreases,and the types are constantly decreasing.(2)The effects of pollutants released from interior materials of locomotive compartments under different temperature and relative humidity conditions were studied.The results show that the external temperature and relative humidity have a certain effect on the release rate of TVOC.Increasing the temperature and humidity will accelerate the release rate of TVOC in the material.The effect of the early release is obvious,and it gradually decreases in the later period.(3)Exploring the release characteristics of interior materials of some cabins under certain conditions,the results show that in the short term,the three materials TVOC release rate wallboard>seat>PVC floor:in the long run,the TVOC release rate in the wallboard is the largest,followed by PVC floor,The seat is the smallest.With the extension of the test time,the TVOC release rate of the three materials wallboard>PVC floor>seat is presented.The reason may be that the VOC components contained in the wallboard and PVC floor material are not easy to emit.At the same time,for the release characteristics of the interior material TVOC,the first-order exponential decay model can be used to fit the release rate of the test material to provide initial values for subsequent simulation calculations.(4)Taking the 25G hard seat car as the research object,using Fluent software to simulate the effect of the emission location on the TVOC distribution of the car.The results show that the different emission locations have different contributions to the TVOC distribution in the ambient air of the car;the closer to the respiratory interface,the contribution The bigger.In the case of no ventilation,the air flow is slower at the opposite ends of the middle of the cabin,resulting in a higher TVOC content in the middle of the cabin than at the ends of the cabin.(5)Using Fluent software to simulate the effect of the emission rate on the TVOC distribution in the cabin,the results show that the TVOC distribution in the cabin environment increases with the acceleration of the interior material release rate,so that the TVOC content on the respiratory interface also increases accordingly.(6)Using Fluent software to simulate the effect of fresh air on the TVOC distribution in the car,the results show that the air enters the car from the upper grille,the speed at the air outlet is higher than that of the non-air supply,and as the air volume increases,the internal speed of the car increases.The degree of internal air disturbance increases,making air and pollutants mix faster;the greater the air volume,the lower the concentration of the respiratory interface inside the cabin.The reason is that with the increase of air volume,the dilution of pollutants in the ambient air of the cabin will be accelerated,so that the concentration of pollutants in the air will be reduced;TVOC also has a situation in which the concentration decreases as the air volume increases in the air supply and non-air supply sections.The TVOC concentration at the air supply section is lower than that at the non-air supply location.In the seat,floor,wallboard and other TVOC locations where the TVOC content is released,the TVOC content is higher than the rest.