Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
A numerical model to simulate smouldering fires in bulk materials and dust deposits
A numerical model is presented which consists of a set of partial differential equations for the transport of heat and mass fractions of eight chemical species to describe the onset of self-ignition and the propagation of smouldering fires in deposits of bulk materials or dust accumulations. The chemical reaction sub-model includes solid fuel decomposition and the combustion of char, carbon monoxide and hydrogen. The model has been validated against lab-scale self-ignition and smouldering propagation experiments and then applied to predictions of fire scenarios in a lignite coal silo. Predicted reaction temperatures of 550 K and propagation velocities of the smouldering front of about 6 mm/h are in good agreement with experimental values derived from lab-scale experiments. The model presented in this paper covers the entire process of fire initialisation and propagation during the storage of a bulk material accumulation. This process is characterised by the following phases: temperature equalisation between the stored material and its surrounding (if initially different), heat accumulation and subsequent temperature rise due to exothermic reactions within the bulk (or dust) deposit, propagation of a smouldering front. However, the results of the computations largely depend on the accuracy and quality of the input data, which normally have to be generated by experiments. Hence, the reliability of the experimental procedures remains a key matter of interest. Undoubtedly, advanced computer modelling of self-ignition and smouldering combustion will more and more become a common tool for assessing the risk of spontaneous fires in solid bulk materials. Current models differ mainly in the number of chemical components considered which is linked to the number of transport equations treated. The model presented here includes seven chemical species, but an extension is limited only by computer resources. A further refinement of the model including the transport of water as liquid and vapour is currently under development.
A numerical model to simulate smouldering fires in bulk materials and dust deposits
A numerical model is presented which consists of a set of partial differential equations for the transport of heat and mass fractions of eight chemical species to describe the onset of self-ignition and the propagation of smouldering fires in deposits of bulk materials or dust accumulations. The chemical reaction sub-model includes solid fuel decomposition and the combustion of char, carbon monoxide and hydrogen. The model has been validated against lab-scale self-ignition and smouldering propagation experiments and then applied to predictions of fire scenarios in a lignite coal silo. Predicted reaction temperatures of 550 K and propagation velocities of the smouldering front of about 6 mm/h are in good agreement with experimental values derived from lab-scale experiments. The model presented in this paper covers the entire process of fire initialisation and propagation during the storage of a bulk material accumulation. This process is characterised by the following phases: temperature equalisation between the stored material and its surrounding (if initially different), heat accumulation and subsequent temperature rise due to exothermic reactions within the bulk (or dust) deposit, propagation of a smouldering front. However, the results of the computations largely depend on the accuracy and quality of the input data, which normally have to be generated by experiments. Hence, the reliability of the experimental procedures remains a key matter of interest. Undoubtedly, advanced computer modelling of self-ignition and smouldering combustion will more and more become a common tool for assessing the risk of spontaneous fires in solid bulk materials. Current models differ mainly in the number of chemical components considered which is linked to the number of transport equations treated. The model presented here includes seven chemical species, but an extension is limited only by computer resources. A further refinement of the model including the transport of water as liquid and vapour is currently under development.
A numerical model to simulate smouldering fires in bulk materials and dust deposits
Numerische Grundlagen für die Modelsimulation von Schwelbränden in gelagerten Feststoffen und Stäuben
Krause, Ulrich (Autor:in) / Schmidt, Martin (Autor:in) / Lohrer, Christian (Autor:in)
2006
9 Seiten, 6 Bilder, 2 Tabellen, 24 Quellen
Aufsatz (Konferenz)
Englisch
Abfalllagerung , Braunkohle , fester Brennstoff , Kohlenmonoxid , Kohlenstaub , Konferenzbericht , Lagerung (Aufbewahrung) , Literaturübersicht , Materialeigenschaft , Modellrechnung , Mülldeponie , Schüttdichte , Schwelen , Selbstzündung , Stoffübergang , Theorie-Experiment-Vergleich , Vereinfachung , Wärmestaustelle , Wärmeübertragung , Wasserdampf , Wasserstoff , Zersetzung
Smouldering Fires in Bulk Materials
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