A multi-segmented human bioheat model for cold and extremely cold exposures

Extremely cold exposure causes human physiological changes and has implications for human health and occupational safety. In this paper, a multi-segmented human bioheat model is developed for predicting human thermoregulatory and physiological responses, especially those of the extremities, under both cold and extremely cold environments. The novel improvements in the model include: 1) the segmental energy balance equations are improved for an extended 22 human body segments; 2) the current model represents the effect of the skin perfusion blood flow on the heat conduction between the skin and core, and further considering the superficial vein blood in peripheral segments (forearms, calves, hands, feet and fingers) and modifying dimensions of the fingers, a more realistic circulatory blood flow system is implemented; 3) the thermoregulatory control equations reflecting the characteristics of human physiological responses to both cold and extremely cold exposure are implemented, including arteriovenous anastomoses (AVAs) in the extremities (feet and fingers), the local skin blood flow decreases by vasoconstriction, and the heat production by shivering. The proposed model is validated and evaluated by comparing the previous models and the published experimental data at a variety of conditions and activity. Furthermore, the experiments on human physiological responses under a range of cold exposures (−5 °C, −10 °C and −15 °C) are conducted in this study, and good agreements between the experimental data of core and skin temperatures and the predicted values of the current model are observed.