Numerical Modeling of Heat and Moisture Through Wet Cotton Fabric Using the Method of Chemical Thermodynamic Law Under Simulated Fire

The paper deals with numerical modeling of heat and moisture transfer behavior of a fabric slab during combined drying and pyrolysis. The model incorporates the heat-induced changes in fabric thermo physical properties and the drying process is described by a one-step chemical reaction in the model. The new model has been validated by experimental data from modified Radiant Protective Performance (RPP) tests of fabrics. Comparisons with experimental data show that the predictions of mass loss rates, temperature profiles within the charring material and skin simulant, and the required time to 2nd skin burn are in reasonably good agreement with the experiments. It is concluded that moisture increases the time to 2nd degree skin burn for fabrics exposed to low intensity heat flux of 21 kW/m², but under high heat flux exposures, such as 42 kW/m², moisture tend to increase heat transfer through the thermal protective fabric system and the tolerance time of the same fabrics will reduce. The model can find applications not only in thermal protective clothing design, but also in other scientific and engineering fields involving heat transfer in porous media.