Filters

2008 - 20092

More filters

20192
Reset filters

Settings

Author: Fuhrmann, Jürgen × Subject: boundary layer ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    A model of an electrochemical flow cell with porous layer
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2009) Ehrhardt, Matthias; Fuhrmann, Jürgen; Linke, Alexander
    In this paper we discuss three different mathematical models for fluid-porous interfaces in a simple channel geometry that appears e.g. in thin-layer channel flow cells. Here the difficulties arise from the possibly different orders of the corresponding differential operators in the different domains. A finite volume discretization of this model allows to calculate the limiting current of the H_2 oxidation in a porous electrode with platinum catalyst particles.
  • Thumbnail Image
    Item
    Experimental and numerical model study of the limiting current in a channel flow cell with a cirvular electrode
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2008) Fuhrmann, Jürgen; Zhao, H.; Holzbecher, E.; Langmach, H.; Chojak, M.; Halseid, R.; Jusys, Z.; Behm, R.J.
    We describe first measurement in a novel thin-layer channel flow cell designed for the investigation of heterogeneous electrocatalysis on porous catalysts. For the interpretation of the measurements, a macroscopic model for coupled species transport and reaction, which can be solved numerically, is feasible. In this paper, we focus on the limiting current. We compare numerical solutions of a macroscopic model to a generalization of a Leveque-type asymptotic estimate for circular electrodes, and to measurements obtained in the aforementioned flow cell. We establish, that on properly aligned meshes, the numerical method reproduces the asymptotic estimate. Furthermore, we demonstrate, that the measurements are partially performed in the sub-asymptotic regime, in which the boundary layer thickness exceeds the cell height. Using the inlet concentration and the diffusion coefficient from literature, we overestimate the limiting current. On the other hand, the use of fitted parameters leads to perfect agreement between model and experiment.