Correction of the evaporative resistance of clothing by the temperature of skin fabric on a sweating and walking thermal manikin

Abstract

Determining the evaporative resistance of clothing by using a sweating thermal manikin requires the accurate skin temperature of the manikin. The skin temperature measured by an embedded wire sensor (EWS), which is widely used in existing manikins, is theoretically higher than that of the wet skin fabric on the manikin where water evaporates. Therefore, we directly measured the surface temperature of the skin fabric using multiple thermistors (MT) and compared it with that of EWS. Four different work clothing ensembles were tested in an isothermal condition. The mean skin temperatures of MT were lower than those of EWS by 0.49, 0.62, 0.75, and 0.89°C, for the manikin walking at 0.00 (standing), 0.27, 0.53, and 0.80 m/s, respectively. Concomitantly, the real evaporative resistances using MT were lower than those using EWS by 9.1, 10.9, 12.5, and 14.4%. These results clearly show that the skin temperature of EWS should be corrected. In our thermal manikin, the temperature difference (TD) (°C) between MT and EWS was calculated for each of five parts: Arm, Trunk, Hip, Thigh, and Calf. The area-weighted average TD of the five parts was expressed as follows: TD = Heat Flux (W/m²) × 0.0092. This equation provides an estimate of TD without measuring surface skin temperature directly and helps to correct the evaporative resistance of clothing ensembles.