Experimental study on overall and local thermal comfort under different radiation intensities

Shortwave radiation constitutes the principal source of thermal loading within automobile cabins, exhibiting characteristics of transient change and non-uniform distribution. However, the PMV-PPD model primarily integrates consideration of shortwave radiation into the mean radiation temperature, and its applicability to distinct radiation scenarios within the passenger compartment still needs to be verified. In addition, different amounts of radiation received by body segments may also affect the local thermal sensation. Few experimental endeavors have systematically investigated the segmental distribution and thermal sensation associated with shortwave radiation across varying radiation intensities. In this study, 12 male college students aged 18 to 28 were selected as the subject group for conducting subjective thermal response experiments. These experiments encompassed diverse radiation intensities (from 100 to 600 W/m2) at three ambient temperatures —22°C (slightly cool), 26°C (neutral), and 30°C (slightly warm). The collected data encompassed radiation reception levels of different body parts, skin temperature, and overall/local thermal sensation voting. The results substantiate that thermal sensation escalates proportionately to heightened radiation intensity, with this trend being more pronounced in warm environments. Moreover, the distribution of received radiation across bodily segments is not uniform, with a stronger correlation between radiation levels and thermal perceptions in upper body segments.