Comment on "Analysis of Char Combustion Including the Effect of Pore Enlargement"

In a current article, Gavalas (1980) considers the effect of pore shape change during the combustion of porous carbon char. The pore enlargement is most rapid near the outer edge of the char particle. The pore radius increases until the mouths of adjacent pores coalesce and cause the recession of the exterior surface. The net influence of this effect is to increase the char reactivity above that predicted by traditional theories (all other variables being equal). When the theory of Gavalas is used to infer an intrinsic rate constant from the data of Smith (1971), it is shown that the inferred rate decreases by a factor of 150 for a 2 percent porous particle and by a factor of 3 at 10 percent porosity.