A Simple PolyUrethane Foam (SPUF) mass loss and response model has been developed to predict the behavior of unconfined, rigid, closed-cell, polyurethane foam-filled systems exposed to fire-like heat fluxes. The model is based on simple two-step mass loss kinetics using distributed Arrhenius reaction rates. The initial reaction step assumes that the foam degrades into a primary gas and a reactive solid. The reactive solid subsequently degrades into a secondary gas. The SPUF decomposition model was implemented into the finite element (FE) heat conduction codes COYOTE [1] and CALORE [2], which support chemical kinetics and dynamic enclosure radiation using "element death." A discretization bias correction model was parameterized using elements with characteristic lengths ranging from 1-mm to 1-cm. Bias corrected solutions using the SPUF response model with large elements gave essentially the same results as grid independent solutions using 100-μm elements. The response model was used to simulate a 9-cm diameter, 15-cm tall cylinder of foam that was heated with lamps. The predictions of the decomposition front locations were compared to the front locations determined from real-time X-rays. The predictions of the front locations were similar to the measured front locations using real time X-rays.
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