(94c) The "Single Pellet Reactor": A “Cool” Multiscale Problem, or a Useful Chemical Engineering POK for Learning of Mass Transfer?

In the field of Chemical Engineering, multiphase mass transport is one of the most important subjects for students to learn since, in general, it is an area of study that sets chemical engineers apart from all other engineering disciplines. Multiphase (and usually systems with mixtures of numerous species and reactions) bring a challenging learning scenario for the beginner, frequently the students! In the current chemical engineering curriculum, the "classical" textbooks used do not provide a systematic, didactic approach for learning mass transfer in systems with multiphase or transient conditions. Unfortunately, more than frequently, students are faced with formulations that seem to be crafted by the "Michelangelos" of the conservation laws rather than effective engineers using general and practical principles.

The "Single Pellet Reactor" offers a useful and practical device to effectively learn the conservation equations for the case of "multiphase" systems and under transient conditions. In this presentation, we will describe an effective approach based on macroscopic species conservation laws to derive the correct "engineering" equations and be able to identify assumptions needed to reach the "classical equations" found in the literature. The approach can be viewed as an effective POK (Arce, 2004) to study multiscale mass transfer in systems with more than one phase. Several observations useful for the learning of students will be drawn at the end of the discussion. Possible relevant scenarios for the experimental determination of parameters will be offered.