Non-Isothermal Cool Flames in Unstirred Static Reactors: A Compressible Model with Global Kinetics

Abstract

A compressible model is developed with kinetics based on the Wang-Mou five-step global kinetic scheme and used to evaluate the temperature, concentration, and velocity fields characteristic of lowtemperature combustion in unstirred static reactors. This work relaxes the assumption of small exothermicity that enabled prior studies to employ the Boussinesq approximation, valid for cases where β T << 1, i.e., slow reactions and cool flames. In this study, the range of validity of the model is extended to cases with large temperature excursions, including multi-stage ignition. For the weakly exothermic cases considered, including modes of slow reaction and cool flames, the Boussinesq approximation is completely adequate. However, it overpredicts the density change and underpredicts the ignition delay time for high-temperature ignitions. Qualitative comparison with experimental results acquired at microgravity conditions are also discussed.

The effect of external heat transfer on thermal explosion in a spherical vessel with natural convection

“…This approximation is commonly used in the analysis of buoyant flows. 17 This approach has been used extensively in the study of thermal explosion, [6][7][8][9][10][11][12][13][14][15][18][19][20] as well as other exothermic reactions, [21][22][23][24][25][26][27][28] under the influence of natural convection.…”