Test And Simulation Of Internal Air Environment Conditions Of Tianjin Subway Line ?

With the rapid development of urban subway,the control over its inner space environment has drawn increasing attention.Guided by“good indoor air quality”,a definition proposed by American Society of Heating,Refrigerating,and Air conditioning Engineers?ASHRAE?,this paper conducted a research on the ambient air in Tianjin Subway Line 1:the internal environment of Tianjin Subway Line 1 in different seasons was researched by subjective questionnaire survey and field test from November,2014 to the end of October,2015.Then,a simulation analysis was carried out based on fluid dynamics simulation software and Airpak,changing the air inlet parameters for an improvement in the compartment interior environment.The results of questionnaire and test show:overall,passengers felt comfortable in summer and winter,but uncomfortable in spring and autumn,especially in spring,uncomfortable accounted for 13.6%.For the fundamental reason that more environmental control measures were adopted in summer and winter than in the transient seasons.This is also an indirect proof for the environment control effect brought by subway air-conditioning.Passengers were particularly unsatisfied with the quality of air in thecompartment due to the bad ventilation effect when the compartment was crowded,objectively manifesting as a high CO₂ concentration.The actual test shows that CO₂concentration was always on the high side and equal to 3300ppm at the highest point in rush hours,particularly in spring.Passengers were most satisfied with the environment in summer since they felt cool after getting in the compartment from the hot external environment,but they felt less comfortable at morning peak hours on workdays since the very crowded compartment led to an increase in the internal relative humidity?persistently higher than 70%?and weakened the effect of ventilation.But the internal temperature decreased slightly when the compartment was less crowded,and at this time,a significant proportion of passengers said they felt a little cold,and that female passengers felt colder than male passengers,so from a perspective of energy conservation,the ambient temperature could be properly raised to achieve the effect of comfort and energy saving.A simulation analysis was carried out by Airpak on the internal environmental indicators in different conditions,drawing a temperature environment nephogram and a CO₂ concentration distribution nephogram for different passenger densities in the designed ventilation condition.Then,the ventilation condition was changed for different passenger densities,not only improving the compartment interior environment,but also reducing excessive energy consumption during subway environmental control.