The Research Of Indoor Environment And Air Quality Of Qinghai-Tibet Air-conditioned Train

The climate characteristics of “high altitude, low pressure, large temperature differencebetween day and night, high solar radiation” along the Qinghai-Tibet Railway determines thesignificant distinction in indoor thermal environment and air quality between theQinghai-Tibet Railway air-conditioned train and the plain area air-conditioned train. Theresearch of the indoor thermal comfort, air quality and thermal environment in theQinghai-Tibet Railway air-conditioned train has important theory value and practical meaningin exploring air-conditioning operation mode, ensuring the passengers’ physical and mentalhealth, saving energy and reducing consumption.The thesis mainly includes:1. The heat transfer process between inside and outside of the train is analyzed by usingthe unsteady heat transfer theoryConsidering the special climate conditions and the body structure thermal inertia ofrunning train along Qinghai-Tibet Railway, the solar radiation absorbed by the train atdifferent times was obtained, in the meantime, the unsteady heat transfer theory program wasused to calculate the related indoor and outdoor parameters and the heat transferred throughthe train envelope.2. The FLUENT software was adopted to numerically analyze caracteristics of theinterior flow field, temperature field and pollutants (CO2) concentration field under conditionsof different outdoor environment parameters and air supply parametersThe heat transfer process between the indoor and the outdoor of the train is a typicalcoupling heat transfer process, which mainly contains three processes “convective heattransfer process between interior air and the interface of the train, heat conduction processinthrough the train envelope and convective heat transfer process between exterior air and theouterface of the train.” The heat originated from passengers is evenly distributed on the seatsurface of the train. The indoor radiation heat transfer among the solid surfaces in the trainwas ignored. Typical meteorological year air-conditioning outdoor design parameters of aregion was adopted to be the calculating parameters of the local station.The basic principle and method of numerical simulation in turbulence k-ε model havebeen discussed in detail. Based on the theory of computational fluid mechanics and heattransfer, the physical model and the mathematical model of25T air-conditioned train wereconstructed, respectively. Interior flow field, temperature field and pollutant concentrationfield were simulated by using the three dimensional turbulence k-ε model under givenassumptions. Obtained the exterior environment parameter characteristics which have a greatimpact on the interior parameters of the train in different locations along the Qinghai-TibetRailway, it mainly contains: exterior air temperature influence on the interior flow field, temperature field and pollutant concentration field; air supply temperature and air speedinfluence on the interior flow field, temperature field and pollutant concentration field;comparison of the above three fields in different situations. The result indicates that: The trainrunning in such a high altitude along the Qinghai-Tibet Railway, solar radiation has atremendous diversity on the interior flow field, temperature field and pollutant concentrationfield. In summer, for T265running from Golmud to Lasa, in order to make the indoor airquality, temperature uniformity, the dilution effect of pollutants as well as oxygenconcentration fit the requirement of standard indoor air quality (GB/T18883-2002), at thesame time, the indoor thermal comfort should be guaranteed,1m/s air supply velocity and21℃air supply temperature should be adopted in Wudaoliang，Tuotuohe and Anduo stations；1m/s air supply velocity and20℃air supply temperature should be adopted in Naqu andDangxiong stations；1m/s air supply velocity and23℃air supply temperature should beadopted in Lasa station. According to the calculation result, it shows that air quality incorridor area is better, but worse in passangers’ head area and door area, pollutantconcentration is beyond the limit of indoor air quality requirements in these areas. All theseresults provide data reference in regulating the air-conditioning refrigerating system, mendingthe cooperation way of oxygen supply system and air-conditioning system, energyconsumption analysis and improving control of indoor environment parameter.Train is like a moving building, the indoor parameters are influenced by many factors.Changeable exterior weather conditions and the special train body structure affect on theindoor thermal environment of Qinghai-Tibet Railway train. To get more perfect operationaldata, we still need to do a lot more meticulous work.