The Effects of Evaporation and Convection on Skin Tissue Temperature Distribution

Recent technological and industrial advances have increased the number of skin burns due to human body exposure to heat in a fire or hot and mechanized environment. In addition, hot environment can produce a strain on a human body leading to discomfort and heat stress and even death. In hot summer days, many people suffer from heat stroke, dehydration and loss of body fluid. Therefore, the subject of studying thermal energy transport in living tissues is useful for assessing skin burns accurately, better understanding the thermoregulatory system of the body and for developing thermal protection standards. In a hot environment, the most important factor to control the body temperature is evaporation. Accordingly, this study solves one dimensional Pennes’ bio-heat equation by means of backward finite difference formulation. Physical and physiological factors taken into account are: sweat secretion, capillary blood circulation (perfusion), metabolic heat, heat and water exchange with the environment through convection and evaporation. Initially, the model is validated using the work of Zhao et al. Then, the evaporation term is added to the model to study the effect of ambient temperature variation on skin tissue temperature. The results show that thermal disease such as hyperthermia can be expected if uncovered skin is held for a specific time at hot environment. It is observed that increasing ambient temperature causes a shift in the location of the maximum temperature toward the surface of the skin, i.e., the maximum temperature occurs at the depth of about 9 and 7.6 mm of skin surface for ambient temperature of 50 and 60°C, respectively.