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Sensibilité, sévérité et spécificités des explosions de mélanges hybrides gaz/vapeurs/poussières

Abstract : The explosion sensitivity and severity of various gas/vapor-dust mixtures have been studied thanks to specifically modified apparatuses based on a 20 L sphere and a Hartmann tube. The specificities of gas/dust hybrid mixtures explosions have been highlighted. In fact, even for gas concentrations lower than the lower explosivity limit (LEL), the ignition probability and the explosion severity can be greatly increased, which will notably lead to great changes in the Ex zones determination. For instance, it has been shown that such mixtures can be explosive when both the dust and gas concentrations are below their respective minimum explosive concentration and LEL. Moreover, synergistic effects have been observed and the rate of pressure rise of hybrid mixtures can be greater than those of the pure gases themselves. The origins of these specificities should not be sought in the modification of a single parameter, but could probably be attributed to combined impacts on hydrodynamics (flame propagation), thermal transfer and combustion kinetics. Experiments have been carried out in order to underline the significance of each contribution. Based on classical shrinking core models taking into account the various limitations during a non-catalytic gas/solid reaction and on homogeneous combustion for gases, a model has been developed to represent the time evolution of the explosion pressure for such mixtures
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Imad Khalili. Sensibilité, sévérité et spécificités des explosions de mélanges hybrides gaz/vapeurs/poussières. Autre. Université de Lorraine, 2012. Français. ⟨NNT : 2012LORR0088⟩. ⟨tel-01749282⟩

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