Experimental investigation of thermal comfort in a passenger car under driving conditions

It is essential to quickly provide an acceptable comfort level in a car by automobile manufacturers during short commutes. Many previous thermal comfort tests for passenger cars were performed in laboratories or under parking conditions, where the thermo-fluid conditions and the driver's perception of thermal comfort may not have been the same as those under outdoor driving conditions. This study conducted tests under outdoor driving conditions, measuring the outside weather conditions, the air and surface temperatures inside a car, and the skin temperatures and thermal sensation votes of the driver under summer conditions. The results show that the air and surface temperatures in the car were non-uniform and decreased rapidly in the first 15 min after the air-conditioning system was switched on. In addition, the thermal comfort conditions in the car did not reach a steady state after 2 h. Thus, a thermal comfort study in a car should be conducted under transient conditions. Reasonably good correlation existed between the mean skin temperature and mean thermal sensation. This study also found that the thermal sensation of the driver under outdoor driving conditions was different from that when the vehicle was parked.