Unsteady airflow and temperature analysis in a subway tunnel with air-conditioned passenger cars

In passenger transportation, especially in subways, air-conditioning in stations and passenger cars is indispensable to keep passengers comfortable. In low altitude cities, closed environmental control systems are designed and applied for their low energy consumption. Car air-conditioners release almost the same amount of heat into the tunnels and stations as a total of other car equipment. This additional heat ejection could cause problems for the normal operation of the station and car equipment, and the environment of the subway tunnels. However, they are not studied quantitatively, because actual measurements and model tests are difficult to be carried out. Here, we report the results of studies on the calculation of unsteady flow distribution and temperature distribution in tunnels. The calculation program is applied to actual system check, such as the temperature variation of passenger cars, the operating conditions of car air conditioners, the design of the station air conditioners, and so on, and proved to be effective.