An individualized thermoregulatory model for calculating human body thermal response in chemical protective clothing

Human thermoregulatory models could be used to assess body temperature and thermal stress in chemical protective clothing. Most models in the literature were exploited based on military standard geometry and without consideration of anthropometric differences in the human body and intensity of exercise during combat tasks in different environments and were seldom applied in chemical protective scenarios. This study aims to develop a thermoregulatory model containing the passive and active systems. The passive system defines human body geometry and tissue physical properties and simulates bio-heat transfer in each segment and between the skin surface and surroundings, while the active system simulates the regulation of metabolism, respiration, circulation and sweating. The heat transfer between two adjacent segments was calculated from blood circulation. The boundary conditions include convection, radiation and evaporation on human skin with or without non-uniform clothing. This study evaluated the model's performance for subjects with basic combat clothing and chemical protective clothing under neutral and adverse thermal environmental conditions. Comparisons with experimental data indicate that the present model is suitable for simulating human thermal responses when exposed to two kinds of ambient temperatures with exercise tasks. Results from the present model were acceptable in the prediction of core and local skin temperature, and the accuracy of the thermoregulatory model for core and skin temperatures could be improved via optimization of specific characteristics of the human body, chemical protective clothing model and the continuous change of physiology under dynamic conditions.