Field Measurement And Numerical Simulation On Indoor Air Environment Of Shanghai Subway Carriage

As the subway carriage is relatively airtight, the amount of fresh air which can be introduced into it is quite limited during the operation. Meaningwhile, harmful substances will easily spread due to high occupant density which can seriously deteriorate indoor air quality (IAQ). In addition, low temperature and high air velocity are likely to cause passengers draught sensation and cold sensation which lead to thermal discomfort in summer. Therefore, questionnaires, field measurements and numerical simulation are carried out to study IAQ and thermal comfort inside subway carriage.In summer, the questionnaire survey was carried out in four different time period covering all the 11 lines in Shanghai, and a large number of samples were collected(over than 2000). The thermal environmental parameters inside subway carriage were also measured while surveying the subjective feeling of passengers. The acceptable temperature range and neutral temperature inside subway carriage in summer were obtained by regression analysis. The results indicate that the temperature inside Shanghai subway carriage is generally lower than the acceptable temperature range, while female's thermal sensation is cooler than male's. Therefore, the operating temperature of H VAC system inside Shanghai subway carriage can be increased in summer.On the basis of measured dynamic thermal environment parameters of major subway lines, the variation characteristics of temperature and humidity inside subway carriage in summer and winter were analyzed. And the relationship between outdoor environment, occupant density, time period, running section and thermal environment inside subway compartment were also discussed. For the ground lines, temperature inside carriage mostly affected by outside environment, but it has little influence on relative humidity. For the underground lines, temperature inside carriage mainly affected by HVAC system, tunnel temperature and occupant density, and the trend of relative humidity curves and temperature curves are more consistent. Based on the validation of numerical model and combined with measurement date of supply air temperature and velocity, the airflow and thermal environment inside carriage were simulated and analyzed using zero-equation turbulence mode. After comparing the temperature fields velocity field and passengers' thermal comfort when using the electric heating device before and after, it reveals that the air distribution is more uniform after using the electric heating device, but the thermal comfort of passenger showed little difference. Therefore, considered from the perspective of energy efficiency and saving initial cost, the subway carriages can just use air conditioning for heating in winter in Shanghai.