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The Chemical Reaction Engineering Module User's Guide

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The Chemical Reaction Engineering Module User's Guide Chemical Reaction Engineering Module User’s Guide Chemical Reaction Engineering Module User’s Guide © 1998–2019 COMSOL Protected by patents listed on www.comsol.com/patents, and U.S. Patents 7,519,518; 7,596,474; 7,623,991; 8,219,373; 8,457,932; 8,954,302; 9,098,106; 9,146,652; 9,323,503; 9,372,673; 9,454,625; and 10,019,544. Patents pending. This Documentation and the Programs described herein are furnished under the COMSOL Software License Agreement (www.comsol.com/comsol-license-agreement) and may be used or copied only under the terms of the license agreement. COMSOL, the COMSOL logo, COMSOL Multiphysics, COMSOL Desktop, COMSOL Compiler, COMSOL Server, and LiveLink are either registered trademarks or trademarks of COMSOL AB. All other trademarks are the property of their respective owners, and COMSOL AB and its subsidiaries and products are not affiliated with, endorsed by, sponsored by, or supported by those trademark owners. For a list of such trademark owners, see www.comsol.com/trademarks. Version: COMSOL 5.5 Contact Information Visit the Contact COMSOL page at www.comsol.com/contact to submit general inquiries, contact Technical Support, or search for an address and phone number. You can also visit the Worldwide Sales Offices page at www.comsol.com/contact/offices for address and contact information. If you need to contact Support, an online request form is located at the COMSOL Access page at www.comsol.com/support/case. Other useful links include: • Support Center: www.comsol.com/support • Product Download: www.comsol.com/product-download • Product Updates: www.comsol.com/support/updates • COMSOL Blog: www.comsol.com/blogs • Discussion Forum: www.comsol.com/community • Events: www.comsol.com/events • COMSOL Video Gallery: www.comsol.com/video • Support Knowledge Base: www.comsol.com/support/knowledgebase Part number: CM021601 Contents Chapter 1: User’s Guide Introduction About the Chemical Reaction Engineering Module 14 The Scope of the Chemical Reaction Engineering Module . 14 The Chemical Reaction Engineering Module Physics Interface Guide . 15 The Material Database. 19 Common Physics Interface and Feature Settings and Nodes . 19 Where Do I Access the Documentation and Application Libraries? . 19 Overview of the User’s Guide 23 Chapter 2: The Chemistry and Reaction Engineering Interfaces Overview of the Reaction Engineering and Chemistry Interfaces 26 Using the Reaction Node. 27 Using the Species Node . 30 Using the Equation View Node — Reactions and Species . 32 Theory for the Reaction Engineering and Chemistry Interfaces 34 Reaction Kinetics and Rate Expressions . 34 The Equilibrium Constant . 35 Handling of Equilibrium Reactions . 39 Reactor Types in the Reaction Engineering Interface . 42 Transport Properties . 49 CHEMKIN Data and NASA Polynomials . 53 Working with Predefined Expressions . 54 References for the Reaction Engineering Interface . 56 CONTENTS | 3 The Reaction Engineering Interface 58 Features Nodes Available for the Reaction Engineering Interface . 67 Initial Values . 67 Reaction . 68 Species . 72 Reversible Reaction Group . 76 Equilibrium Reaction Group. 78 Species Group . 79 Additional Source . 80 Reaction Thermodynamics . 81 Species Activity . 81 Species Thermodynamics. 81 Feed Inlet. 82 Generate Space-Dependent Model . 83 Parameter Estimation . 91 Experiment . 92 The Chemistry Interface 95 Feature Nodes Available for the Chemistry Interface . 100 Reaction . 100 Species . 105 Reversible Reaction Group . 108 Equilibrium Reaction Group. 109 Species Group . 111 Reaction Thermodynamics . 111 Species Activity . 112 Species Thermodynamics. 112 Study Steps for the Reaction Engineering Interface 113 Reactor Types and Solver Study Steps . 113 Solver Study Steps for Parameter Estimation . 113 Chapter 3: Chemical Species Transport Interfaces Overview of Chemical Species Transport Interfaces 117 Available Physics Interfaces . 117 4 | CONTENTS Coupling to Other Physics Interfaces . 119 Adding a Chemical Species Transport Interface and Specifying the Number of Species. 119 Theory for the Transport of Diluted Species Interface 122 Mass Balance Equation . 123 Equilibrium Reaction Theory . 124 Convective Term Formulation. 126 Solving a Diffusion Equation Only . 127 Mass Sources for Species Transport . 127 Adding Transport Through Migration . 129 Supporting Electrolytes . 130 Crosswind Diffusion . 131 Danckwerts Inflow Boundary Condition . 132 Mass Balance Equation for Transport of Diluted Species in Porous Media . 133 Convection in Porous Media . 134 Diffusion in Porous Media . 136 Dispersion . 137 Adsorption . 139 Reactions. 141 Mass Transport in Fractures . 142 Theory for the Reactive Pellet Bed . 143 References . 151 Theory for the Transport of Concentrated Species Interface 153 Multicomponent Mass Transport . 153 Multicomponent Gas Diffusion: Maxwell-Stefan Description . 154 Multicomponent Diffusivities . 156 Multicomponent Diffusion: Mixture-Averaged Approximation . 158 Multispecies Diffusion: Fick’s Law Approximation . 160 Multicomponent Thermal Diffusion . 161 Regularization of Reaction Rate Expression . 161 References for the Transport of Concentrated Species Interface. 162 CONTENTS | 5 Theory for the Electrophoretic Transport Interface 163 Theory for the Surface Reactions Interface 169 Governing Equations for the Surface Concentrations . 169 Governing Equations for the Bulk Concentrations . 170 ODE Formulations for Surface Concentrations . 172 Surface Reaction Equations on Deforming Geometries . 173 Reference for the Surface Reactions Interface . 174 Theory for the Nernst-Planck Equations Interface 175 Governing Equations for the Nernst-Planck Formulation . 175 Convective Term Formulation. 177 Theory for the Reacting Laminar Flow Interface 178 Pseudo Time Stepping for Mass Transport . 178 The Stefan Velocity . 178 The Chemical Reaction Rate . 180 The Transport of Diluted Species Interface 182 The Transport of Diluted Species in Porous Media Interface . 186 Domain, Boundary, and Pair Nodes for the Transport of Diluted Species Interface. 187 Transport Properties . 189 Turbulent Mixing . 191 Initial Values . 191 Mass-Based Concentrations. 192 Reactions. 192 No Flux . 193 Inflow . 194 Outflow . 195 Concentration . 195 Flux . 196 Symmetry . 197 Flux Discontinuity . 197 Partition Condition . 197 Periodic Condition . 198 Line Mass Source. 199 Point Mass Source . 200 6 | CONTENTS Open Boundary . 200 Thin Diffusion Barrier . 201 Thin Impermeable Barrier . 201 Equilibrium Reaction . 201 Surface Reactions . 202 Surface Equilibrium Reaction . 203 Fast Irreversible Surface Reaction . 203 Porous Electrode Coupling . 204 Reaction Coefficients . 204 Electrode Surface Coupling . 205 Porous Media Transport Properties. 205 Adsorption . 207 Partially Saturated Porous Media . 209 Volatilization . 211 Reactive Pellet Bed . 212 Reactions (Reactive Pellet Bed) . 215 Species Source. 216 Hygroscopic Swelling . 217 Fracture . 217 The Transport of Diluted Species in Fractures Interface 219 Boundary, Edge, Point, and Pair Nodes for the Transport of Diluted Species in Fractures Interface . 221 Adsorption . 222 Concentration . 223 Flux . 224 Fracture . 224 Inflow . 225 No Flux . 226 Outflow . 226 Reactions. 226 Species Source. 227 The Transport of Concentrated Species Interface 228 Domain, Boundary, and Pair Nodes for the Transport of Concentrated Species Interface . 234 Transport Properties . 235 Porous Media Transport Properties. 239 CONTENTS | 7 Electrode Surface Coupling . 242 Turbulent Mixing . 243 Reaction . 244 Reaction Sources. 245 Initial Values . 246 Mass Fraction . 247 Flux . 248 Inflow . 249 No Flux . 250 Outflow . ..
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