Burning of small particles - diffusion versus kinetic limits

Burning of Small Particles - Diffusion versus Kinetic Limits 

Recall the diffusion controlled burning rate of a particle with fast heterogeneous reactions at the surface given by Eq. (9.29) 

For kinetically controlled combustion, Eqs. (9.9), (9.17), and (9.34) yield for the mass burning rate 

The combustion time from the initial particle size to burnout is 

th in a kinetically controlled regime is described by a dl law. Furthermore, th is found to be inversely proportional to pressure (for a first-order reaction) under kinetically controlled combustion, and in contrast, independent of pressure under diffusionally controlled combustion (since D P-1). In the kinetically controlled regime, the burning rate depends exponentially upon temperature. 

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