Fluid–Solid Reaction Kinetics for Solids of Non-basic Geometries: Application of the Law of Additive Times in Combination with the Shape-Factor Method

Fluid–Solid Reaction Kinetics for Solids of Nonbasic Geometries: Comparison of the Sohn–Wall Method and the Shape-Factor Method

“…Further, the application of Sohn’s law of fluid–solid reactions combined with the shape-factor method was proven to give a satisfactory simple equation for conversion–time relationships for solids of any shapes. Since the Sohn–Wall method for pore-diffusion-controlled reaction yields results that are close to both the exact numerical solution and the shape-factor method, it is reasonable to expect that either of the approximate methods may be used in combination with Sohn’s law to describe the X – t relationships for the reactions of solids of any shape, as described by the following ,,, If the overall rate is significantly affected by external mass transfer, the time required to reach the same conversion under the control of external mass transfer, given by the following equation, may be added where k m is the external mass transfer coefficient.…”

“…[ h 1 and h 2 are the ratios of the largest and the second-largest dimensions to the smallest dimension of the solid, respectively.] (Adapted from Sohn et al)…”

Development of Solid–Fluid Reaction Models—A Literature Review

“…Therefore, the shrinking core model is also called the product layer model by some investigators [14]. For the reactions with no product layers formed outside the unreacted core, when products are either dissolved in the surrounding fluid or removed immediately from the outer surface of the solid, the shrinking core model is also called shrinking particle model, such as in the case of pure carbon combustion in oxygen, and the solid/liquid reaction producing gas products [30][31][32][33]. Some investigators considered the cracking of the nonporous particle during the reaction, and proposed the cracking core model [34,35], which assumes that the initial nonporous particle is transformed to a grainy material, which then reacts following the shrinking core model.…”

“…The pores will become larger and the overall rate is independent of the solid size. The overall solid size does not change until the solid particle is highly converted [32,[36][37][38]. The reaction process is shown in Figure 3.…”

“…Therefore, the shrinking core model is also called the product layer model by some investigators [14]. For the reactions with no product layers formed outside the unreacted core, when products are either dissolved in the surrounding fluid or removed immediately from the outer surface of the solid, the shrinking core model is also called shrinking particle model, such as in the case of pure carbon combustion in oxygen, and the solid/liquid reaction producing gas products [30][31][32][33].…”