Heat transfer model for the effects of boundary conditions on transient vapor generation rates in pool fires - A Ecart numerical tool dynamics model

Mathematical model simulating some phenomena of the dynamical development of a pool fire. The model is finalized to quantify the vapour mass release rate, from the pool to the surrounding air, caused by pool liquid heating consequent of radiative and convective heat transfer phenomena between flame (and eventually other high temperature bodies) and pool. The lumped parameters grid theory is used to model the pool heat transfer and vapor generation phenomena and a “grid” model has been developed to extend the capability of ECART numerical tool (fast running computer code dedicated to predict the consequences of an accident in a risk installation). Model development was focused on the implementation inside such code. After an approximate first validation of a model stand-alone version, it was implemented inside ECART. The first step model validation was carried out by comparison with references data and experimental pool fire test results performed by the model developer’s team. The maximum burning rate, the pool fire duration and the development of phases I (growth - transitory period corresponding to fire development), II (steady-state period corresponding to fully developed fire, with an about invariable burning rate) and III (exhaustion - transitory period preluding the end of fuel, during which both the size of flames and the burning rate decreased continuously up to fire extinction) are mainly analyzed. The model approach based on the grid theory appears as a good mechanistic type and fast-running method for simulating the pool fire dynamics and performing interpretative and predictive analysis of fire scenarios including hydrocarbons pool fires. Particularly satisfying is the reproduction of phases I, II and III of the transient. We underline that grid model is focused only on the quantification of vapour mass flow released from the pool to surrounding air, and so it need a combustion model, flame model and other tools to perform fire scenario numerical simulations. Then, from this point of view, the preliminary comparison between the results provided by the grid model and experimental data is considered rather satisfactory and so the model approach appears as a effective fast-running means for simulating the pool fire dynamics and it is worthy of further investigation and development.