Study on the heat transfer of subway cain under various experimental conditions

초록

Vehicle heat transfer is one of the most basic, but important factor presenting the performance of the vehicle. Nowadays, due to the high energy cost, the energy saving during heating or cooling is getting more important. For this reason, many railroad operators want subway car with lower vehicle heat transfer. However, most of subway cars have high heat transfer rate because their bodies are made of metal which has a high heat transfer coefficient. The measurement of vehicle heat transfer is the first step to evaluate the heating or cooling performance of subway car, but it has not been carried out until now since the evaluation was replaced by the calculation in many cases. However, because the calculation of vehicle heat transfer can not reflect all aspects of the car, and the vehicle heat transfer test using a real-scale climatic chamber is required by railroad operators. In this study, vehicle heat transfer of a testing subway cabin was measured by using a real-scale climatic chamber. The effect of ambient temperature, number of operating fans, output of heaters, additional installation of insulating panels were studied. It was found that the ambient temperature, number of operating fans did not influence on the heat transfer. However, the output of heaters significantly influenced on the heat transfer. When the heater output was larger, the heat transfer was also larger due to the more heat loss at higher heater output. Additional installation of insulating panels also contributed in the decrease of heat transfer since it blocks the heat transfer through the walls of the subway cabin. It was also found that heat transfer through the windows or doors should be significantly reduced to obtain lower heat transfer value.