Induction times for thermal explosion and natural convection in porous media

✍ Scribed by H.J. Viljoen; J.E. Gatica; V. Hlavacek

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 505 KB
• Volume: 43
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(88)80048-4

✦ Synopsis

Thermal explosion occurs when the heat generation of an exothermic reaction exceeds the system's capacity of heat removal. In fluid systems, natural convection acts as an additional heat transfer mechanism, and, for sufficiently large values of the Rayleigh number, the system can be stabilized. The evolution of this secondary flow is charactcrizcd by an induction period. Initially, the natural convection develops at a slow rate, but, after an induction time, it grows explosively. Equations are derived to determine the time to thermal explosion as we11 as the induction period for natural convection. Important parameters, such as the type and magnitude of the initial perturbation, and the aspect ratio of the cavity, are considered. Numerical results that support the validity of the equations are reported.