1 / 10

Example: Adsorption and Heterogeneous Reactions

This study investigates a small parallel plate reactor featuring an active surface, exploring the unique coupling of surface reactions with volume processes using COMSOL Multiphysics. The approach incorporates mass balance equations for surface diffusion and reaction kinetics within a 2D flow channel, coupled with a 1D surface model through a weak boundary condition. The research emphasizes the importance of surface concentration dynamics in heterogeneous reactions and demonstrates the versatility of multiphysics modeling for chemical processes on varying scales.

dominy
Télécharger la présentation

Example: Adsorption and Heterogeneous Reactions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Example: Adsorption and Heterogeneous Reactions

  2. Introduction • Small parallel plate reactor with an active surface is studied. These types of processes are found in heterogeneous reactors, biacores, etc. • The problem shows one of the most unique COMSOL Multiphysics features; coupling phenomena defined in different dimensions. In this case, a surface process is coupled to a process defined in a volume. • Mass balance is defined on the surface with surface diffusion and surface reaction rates using a “tangential PDE”. This, and the corresponding adsorbing and desorbing processes, can be coupled to the 2D problem through a (weak) boundary expression.

  3. Geometry • The flow channel is modeled with a geometry and PDE in 2D • The active surface is modeled with another PDE that ”lives” in 1D space only

  4. Coupling Scheme

  5. Weak Form • The surface equation needs to be defined in a 1D weak application mode, and it is coupled to the 2D PDE through a boundary condition: General Form: where: • “Tangential PDEs have derivatives in the direction of the tangent-plane to the surface only

  6. Weak Form (continued) Multiply by test function v and integrate: Perform integration by parts on left hand side: Rearranged: weak=Ds*(-csTx_test*csTx-csTy_test*csTy)+cs_test* (kads*c*(theta0-cs)-kdes*cs) In COMSOL Multiphysics: dweak=cs_test*cs_time

  7. Concentration in the Bulk and at the Surface Increase in lateral supply of reactant

  8. Surface Concentration as Function of Time at the Surface

  9. Time Evolution in Bulk

  10. Concluding Remarks • The model is highly relevant for heterogeneous reactions in the cases where the surface concentrations have to be accounted for. • Access to the weak form gives added flexibility. • Other uses for extended multiphysics can include: • Coupling process control to chemical/transport processes • Modelling phenomena on different scales, such as packed beds

More Related