Weighting Coefficients for Calculating Mean Skin Temperature when Considering Convective Heat Tranfer Areas

Abstract

When accurately quantifying convective heat exchange between the human body and the surrounding environment, mean skin temperature is determined by measuring the skin temperature of areas of the body surface exposed to airflow (hereinafter referred to as the convective heat transfer area) and then calculating the ratio of the convective heat transfer area with the uniform skin temperature to the total convective heat transfer area. Thus we must consider convective heat transfer areas to determine mean skin temperature. In this study, the convective heat transfer area of the human body in two basic postures (standing on the floor and sitting on a chair) was measured by dividing the body surface into smaller sections. We then proposed weighting coefficients for calculating mean skin temperature taking into account convective heat transfer areas, and conducted experiments to clarify how convective heat transfer areas affected calculations of mean skin temperature. The results showed that, for both standing and sitting positions, due to the areas of contact between two body surfaces and between the body and the floor, the convective heat transfer area for the hand and foot regions was markedly small. We then calculated weighting coefficients for calculating mean skin temperature that take into account convective heat transfer areas for standing and sitting positions. The tendency was that the smaller the ratio of convective heat transfer area to the total body surface area, the greater the difference in mean skin temperature using the Hardy-DuBois technique. The results of the present study also clarify that by taking into account convective heat transfer areas, the skin temperature of the extremities can be reflected in mean skin temperature for both standing and sitting positions.