An analysis is developed for the mixed, forced and free, convective gasfication, ignition, steady burning and extinction at the stagnation point of a condensed fuel particle. The analysis makes use of the boundary layer approximation to describe the gas flow, of the flamesheet approximation to analyze the fuel burning process, and of large activation energy asymptotics to study the ignition and extinction phenomena. A mixed-convection parameter is introduced in the formulation of the problem in such a way that the forced or free conditions are respectively recovered for zero value of the Grashof or Reynolds number. This unified formulation of the problem permits the derivation of general criteria for ignition and extinction, and the description of the gasification and burning processes when the fuel particle is subjected to convective flows of different nature and intensity. Explicit expressions are derived for the gasification and mass burning rates and for the critical Damköhler numbers for ignition and extinction.
All Science Journal Classification (ASJC) codes
- General Chemical Engineering
- Fuel Technology
- Energy Engineering and Power Technology
- Mechanical Engineering
- Physical and Theoretical Chemistry
- Fluid Flow and Transfer Processes