Study of heat transfer through multilayer protective clothing at low-level thermal radiation

The goal of this research is to develop a mathematical model of heat transfer in protective garments exposed to routine fire environment (low level of radiant heat flux) in order to establish systematic basis for engineering materials and garments for optimum thermal protective performance and comfort. In the first stage, this paper focuses on the formulation of heat transfer model suitable for predicting temperature and heat flux in firefighter protective clothing, using COMSOL Multiphysics® package based on the finite element method. Computational results show the time variation of the temperature at the inner face of the protective clothing system during the exposure to a low-radiant heat flux as well as during the cooling-down period. Model predictions of the temperature agreed very well with the experimental temperature. In the second stage of this study, in order to predict the first and second-degree burns, the model of heat transfer through multilayer protective system was coupled with the heat transfer model in the skin. The Pennes model was used to model heat transfer in the living tissue. The duration of exposure during which the garment protects the firefighter from getting first and second-degree burns is numerically predicted using Henriques equation. The results demonstrated that even for a low-level thermal radiant heat flux, a typical three-layer thermal protective clothing system is required to protect the wearer from skin burn injury.