The technical staff at COMSOL has developed this special COMSOL ECRE Version (also referred to throughout this book simply as COMSOL ECRE) exclusively for H. Scott Fogler’s book Elements of Chemical Reaction Engineering. As you will see in the following pages, COMSOL Multiphysics is an exceptionally powerful tool for performing PDE-based modeling and simulations in a broad number of disciplines, but here we focus on energy and mass balances. To help you better understand the underlying physics and principles, the COMSOL Multiphysics engine runs a number of ready-made models in which you can change key parameters and observe the results. Thus, the accompanying CD includes the COMSOL Multiphysics computational engine along with six complete models and full documentation. These illustrative models combine energy and mass balances in both isothermal and non-isothermal conditions using the appropriate application modes in COMSOL Multiphysics.
We have divided the examples into two section. The first section treats radial effects in tubular reactors induced by velocity distribution along the radius, and it examines the effects of external cooling at a reactor’s outer wall. The second section deals with dispersion effects in tubular reactors, and it compares different assumptions for the inlet and outlet boundary conditions. It also compares 1-dimensional models with the solutions from axisymmetric models.
More specifically, the models we present are:
The two dispersion models in the second set investigate the Danckwerts boundary conditions by comparing them with results obtained from a reactor model that adds an inlet and outlet section.
In all of these models you can change input data—such as rate constants, flow rates, diffusivities, and conductivities—and have COMSOL Multiphysics again solve the model. It is also possible to visualize results through ready-made expressions or by entering arbitrary expressions of the solution variables into COMSOL Multiphysics.
The immediately following section provides a brief introduction to COMSOL Multiphysics and the Chemical Engineering Module, which together form the basis for the models just listed. If you are already familiar with COMSOL Multiphysics and would prefer to start with the exercises immediately, proceed to Chapter 2.