Development of a sweating thermal skin simulant for heat transfer evaluation of clothed human body under radiant heat hazard

•First development methodology of sweating thermal skin simulant.•Same temperature variation behaviors between skin simulant and numerical model.•Revealing effects of active liquid sweating on heat transfer through human skin.•Counterbalance between thermal conductivity and specific heat of moisture. Human perspiration highly affects body heat dissipation as well as heat and mass transfer in clothing systems. Nevertheless, current skin simulant systems for assessing heat transfer under high heat exposures simply simulate the dry skin state. This fact limits the validity of such systems as perspiration and mass transfer exist during high heat exposure conditions. In this study, an active sweating skin simulant was developed using the polydimethylsiloxane material and with controllable sweat rates for heat transfer assessment under radiant heat hazards, considering mass transfer as well. In the dry state, the temperature and its variation rate of the skin simulant with water-filled sweating channels showed good agreement with the ISO standard numerical model. For sweating conditions, the results showed that the wet conduction facilitated heat transfer towards the skin by 5–8 % at the beginning of sweating. With continuous sweat release, the surface temperature rise was attenuated due to the additional heat capacity induced by additional moisture in the clothing-skin system. The low standard deviations, below 2 °C, and coefficients of variation, below 10%, for the temperature measurements under various sweat rates, indicated good reproducibility of the skin simulant. This research provides the first approach to consider active sweating in skin simulant systems under high heat exposures. This further provides new insights into heat transfer in protective clothing-human skin systems under extreme heat exposures, contributing to realistically evaluating the thermal protective performance of clothing materials under sweating conditions.