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Modeling Reaction and Distribution of Water in Nanopores of the Cathode Catalyst Layer of PEM Fuel Cell

Nushak, Fatemeh | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43453 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): baghalha, morteza
  7. Abstract:
  8. In the proton exchange membrane fuel cells (PEM, the produced water would be divided into two phases of vapor and liquid. distribution of both liquid and vapor phases in different cell layers affects the performance, the efficiency and the life of a fuel cell significantly. Moreover, Nano pores of the cathode catalyst layer are involved with some phenomena such as electrochemical reaction kinetics, heat and mass transfer and interface phase change. One of the most important problems in the performance of fuel cells is distribution of liquid water in the porous areas. Water flooding in fuel cells causes to delay in oxygen transport to active sites in the catalyst layer because the pores of catalyst layer and gas diffusion layer blocks. So focus on the problem of water distribution and it's effective factors can improve the performance of cell. In this work a two-dimensional, non-isothermal, two phase and steady state model for a PEM fuel cell cathode catalyst layer is described. As a matter of fact, the model which is presented for cathode catalyst layer can calculate the distribution of water, gas components and temperature by taking the information of other layers as catalyst layer boundary conditions, in which catalyst layer is merely considered. In addition, theobtained saturation distribution from the numerical results is consistence with experimental data and the multicomponent diffusion, heat transfer within the solid matrix and the fluid, phase change and liquid water transport were studiedas well.We assumed that %10 of produce water via reaction is generated as vapor and 90% of it is liquid. After modeling about 86% of the existing water left the boundary of the gas diffusion layer and catalyst layer as a liquid and the rest changed into vapor. andBesides, the effect of different parameters such as temperature, the current density, permeability etc. is evaluated on the distribution of liquid water saturation of the catalyst layer. Finally, it can be mentioned that the numerical solution which is performed in this study has been done by the COMSOL software.
  9. Keywords:
  10. Water Distribution System ; Proton Exchange Membrane (PEM)Fuel Cell ; Reaction Modeling ; Proton Exchange Membrane (PEM)Fuel Cell Catalyst Layer

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