Development of thermal resistance prediction model and measurement of thermal resistance of clothing under fully wet conditions

Abstract

When clothing is immersed in water, the water will rapidly occupy the internal void of the clothing, and the air layer inside the clothing will disappear, which leads to a drastic reduction in the thermal resistance of the clothing. To calculate the thermal resistance of clothing under fully wet conditions, a novel serial method was proposed. The method is a combination of the thermal resistance of water and the thermal resistance of wet fibers. To verify the effectiveness of the new method, the thermal resistances of three typical suits under fully wet conditions were measured. Three typical suits, a summer suit (T-shirt + shorts), a spring suit (sportswear + sweatpants), and a winter suit (cotton coat + wool pants), were chosen as test objects. The thermal resistances of these suits under fully wet conditions were measured in an experimental water tank built in a chamber using a thermal manikin, “Walter.” The thermal resistance measurement in this study can eliminate the experimental error caused by the evaporation of water so as to obtain an accurate thermal resistance measurement. According to the experimental results and the model, the key factors affecting the thermal resistance under fully wet conditions were thickness (R_pearson = 0.992), porosity (R_pearson = 0.980), and moisture content (R_pearson = 0.964). Compared to other thermal resistance prediction models, the prediction results by the novel method were more consistent with the measured results, with all deviations less than 10% and the correlation value R² = 0.998.