3. Where reaction volume and/or transfer properties are variable

The aim of these models is not to accurately represent the composition and temperature profiles within the transforming particle, but to specify as precisely as possible the rate of transformation of the consumable solid phase, and the variations in this rate of transformation as a function of external operating conditions.

In what follows, we will describe three particular types of consumable transformations belonging to this second family, which encompass all the consumable transformations in this family:

• the consumable transformation of the reactive solid phase leads only to one or more gaseous products;

• the consumable transformation of the reactive solid phase leads to a gaseous product and a solid product, but there is no variation in particle size during the transformation;...