Electric circuit analogy of heat losses of clothed walking human body in windy environment

Abstract

In this study, a simplified approach for the estimation of the segmental heat losses from the human body to the environment is developed. The approach is based on a heat resistance model that predicts the latent and sensible heat losses while incorporating an analogy between the air flow and an electric circuit to determine the clothed limb or trunk segment ventilation induced by motion and wind. The estimation of the segmental ventilation allows the correction of the clothing dry/evaporative resistances in the heat resistance network to determine the dynamic resistance. The circuit models of heat and ventilation are validated by conducting experiments on a thermal manikin investigating the following cases: (i) no wind and no walking conditions (ii) wind (0.8 m/s) without walking condition (iii) walking (0.8 m/s) without wind (iv) wind (0.8 m/s) and walking (0.8 m/s) conditions. It was shown that the sensible heat loss segmental predictions of the circuit models were within the standard deviation range of the performed experiments.The heat and ventilation circuit models are then integrated with a bio-heat model to calculate accurately the segmental skin temperature and sensible and latent heat losses from a clothed human under walking and wind conditions. The effect of ambient conditions on the latent and sensible heat losses and the effect of walking and wind speed on the thermal insulation are validated using available published experiments.