General mass burning considerations and the evaporation coefficient

General Mass Burning Considerations and the Evaporation Coefficient 

Three parameters are generally evaluated the mass burning rate (evaporation), the flame position above the fuel surface, and the flame temperature. The most important parameter is the mass burning rate, for it permits the evaluation of the so-called evaporation coefficient, which is most readily measured experimentally. 

The use of the term evaporation coefficient comes about from mass and heat transfer experiments without combustion—that is, evaporation, as generally 

This same equation holds whether or not there is mass evolution from the surface and whether or not convective effects prevail in the gaseous stream. Even for convective atmospheres in which one is interested in the heat transfer to a surface (without mass addition of any kind, i.e., the heat transfer situation generally encountered), one writes the heat transfer equation as 

The (Ta - Ts)/8 term is the temperature gradient, which correlates (dTIdy through the boundary layer thickness. The fact that 8 can be correlated with the Reynolds number and that the Colburn analogy can be applied leads to the correlation of the form 

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