Thermal comfort analysis in a passenger compartment considering the solar radiation effect

The present study numerically investigated thermal comfort in a passenger compartment by considering the spectral solar radiation. With the use of commercial software (ANSYS Fluent V. 13.0) in which the solar load model is embedded, a three-dimensional computational fluid dynamics simulation was conducted to accurately predict thermal and flow fields under the operating conditions of a heating, ventilation, and air conditioning system. This study compared the Fanger model and the equivalent temperature model for thermal comfort analysis, together with the numerical predictions which could be used for estimation of the predicted percentage of dissatisfied, the predicted mean vote, and the equivalent temperature as the important indices in evaluating thermal comfort. From the results, the estimated temperature near the driver and passengers increased by approximately 1-2 °C when considering the spectral solar radiation. This small difference in air temperature caused a substantial variation in thermal comfort level inside the compartment. In addition, it was found that when the spectral solar radiation effect was involved, the predicted mean vote was higher than that of the case without considering the spectral radiation. Through comparison between two thermal comfort models, it was noted that the spectral solar radiation must be considered in evaluating thermal comfort levels, and unlike the Fanger model, the equivalent temperature model could predict the local variations of thermal comfort levels in the compartment.