Teaching Nonideal Reactors with CFD Tools

Authors

  • Luis Madeira Universidade do Porto
  • Manuel A. Alves Universidade do Porto
  • Alírio E. Rodrigues Universidade do Porto

Abstract

In this paper, a computational fluid dynamics (CFD) code (Fluent) was used to illustrate important concepts regarding residence time distribution (RTD) theory. The case study adopted considers isothermal laminar flow through 2-D reservoirs of different geometries (various length/height, L/H, ratios), and a tracer step input is simulated for RTD determination. From the steady-state solution, quasi-stagnant zones are easily identified, particularly for high flow rates (or, more rigorously, high Reynolds numbers) and for low L/H ratios. In some cases, the fraction of dead volumes amounts to values as high as 7 0%. For high L/H ratios, one approaches the theoretical RTD for laminar flow between parallel plates. Transient simulations are also very useful because they allow "visualization" of the evolution of tracer concentration fronts, which animation is available on our web site. The RTD obtained allows students to predict a reactor's performance, either in steady-state or transient regime. Such information can also be obtained directly from Fluent by simulating the injection of a reactive feed stream. The use of a commercially available CFD tool is illustrated to be advantageous, as it allows students to easily visualize and understand the involved concepts, namely flow pattern and behavior/diagnosis of nonideal reactors.

Author Biographies

Luis Madeira, Universidade do Porto

Luis M. Madeira is Assistant Professor of Chemical Engineering at the University of Porto (Portugal). He graduated in Chemical Engineering (1993) and received his PhD (1998) from the Technical University of Lisbon. He teaches chemical engineering laboratories and chemical reaction engineering. His main research interests are in catalytic membrane reactors, heterogeneous catalysis (including environmental catalysis), and fuel cells.

Manuel A. Alves, Universidade do Porto

Manuel A. Alves is a Teaching Assistant in the Chemical Engineering Department at the University of Porto (Portugal). He graduated in Chemical Engineering from the University of Porto in 1995. His main research interests are in the simulation of viscoelastic flows and the development of numerical algorithms for computational fluid dynamics.

Alírio E. Rodrigues, Universidade do Porto

Alírio E. Rodrigues is Professor of Chemical Engineering at the University of Porto (Portugal). He graduated in Chemical Engineering from the University of Porto in 1968 and received his Docteur-lngenieur degree at the University of Nancy (France) in 1973. He is Director of the Laboratory of Separation and Reaction Engineering-LSRE (www.fe.up.pt/lsra).His main research interests are in cyclic separation/reaction processes (simulated moving bed, pressure swing adsorption, and parametric pumping technologies) and chemical reaction engineering.

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Published

2004-04-01

Issue

Vol. 38 No. 2 (2004): Spring 2004

Section

Manuscripts