Inverse heat transfer modeling applied to the estimation of the apparent thermal conductivity of an intumescent fire retardant paint

Intumescent paints are widely used as passive fire protective materials in the building sector, primarily with regard to steel framed structures. The fire resistance of commercial intumescent coatings is typically tested experimentally using expensive and time consuming large-scale tests; conversely, the increasingly common performance-based fire safety engineering approach requires the development of techniques to generalize and predict the behavior of these protective materials. Recently, an experimental and data processing technique based on temperature measurements of the growing char layer and on the formulation of the inverse heat conduction problem within the system, has been proposed. This investigation indicated that an accurate and complete modeling approach is required to make robust predictions in the processing of the experimental data. In this paper, an enhanced procedure for estimating the apparent thermal conductivity of the intumescent paint is proposed and validated. The analysis presented in this study, performed with a physical and chemical characterization of the intumescent paint, allows estimation of the apparent thermal conductivity of the char layer with good approximation, thereby providing important information for assessing the fire protective capability of the coating under the fire safety engineering approach.