Convection Effects on the Endothermic Gasification and Piloted Ignition of a Radiatively Heated Combustible Solid
作者:
J.L. CÓRDOVA,
A.C. FERNANDEZ-PELLO,
期刊:
Combustion Science and Technology
(Taylor Available online 2000)
卷期:
Volume 156,
issue 1
页码: 271-289
ISSN:0010-2202
年代: 2000
DOI:10.1080/00102200008947306
出版商: Taylor & Francis Group
关键词: Solid Fuel Ignition;Piloted Ignition;Pyrolysis;Flammability
数据来源: Taylor
摘要:
A study is presented on the effect of convective conditions on the endothermic gasification and subsequent ignition of a slab of solid material heated by a radiant flux. A simple solid-phase thermal model is numerically integrated to approximately reproduce results of a previous experimental study of piloted ignition. The model is formulated in terms of the transient energy equation including endothermic Arrhenius-type pyrolysis and Beer-law in-depth absorption of the radiant flux. Temperature evolution curves are obtained for different values of the heat flux and convective coefficient, and are shown to accurately predict experimental surface temperature measurements prior to ignition. Material gasification rates are calculated and used in conjunction with the experimental ignition results to show that the piloted ignition delay closely corresponds to the time required by the solid to reach a critical value of the gasification rate. The critical gasification rate is nearly constant and independent of the heat flux for given convective conditions, and increases linearly with the convective coefficient. It is shown that the graphs of piloted ignition delay vs. heat flux may be accurately determined from this critical gasification criterion. Finally, a non-dimensional parameter that represents the relative amount of gasified fuel transported by the oxidizer stream is presented as a suitable measure of the flammability of the material.
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