Mass Conservation Equations The equations of continuity are: The general form of transport equations in the flow channels and porous media are as follow 2.2.1. The source terms changes from one element to the other. Governing Equations The nature of deferent elements of the PEM fuel cell is not the same. Only the steady-state case is considered. The gas mixture flows are incompressible. All water produced in the electrochemical reactions is assumed to be in the gas phase, and phase change and two phase-transport are not considered. The porous media including membrane, catalyst layers and GDLs are considered to be isotropic. The fluid flow in the fuel cell is laminar due to the low flow velocities and the small size of gas flow channels. Model Assumptions The assumptions used in developing the model are as follows: -Ideal gas law is employed for gaseous species. 1 with the geometrical parameters as listed in Table 1( same geometrical parameters as in). In this paper, the mathematical model considers all the parts shown in Fig. Between the current collectors and the MEA are included two GDLs on both sides. 1 shows a schematic diagram of a PEMFC compared of two distinct current collectors with flow channels formed on to both the cathode and anode and the MEA consists of a proton exchange membrane sandwiched between two catalyst layers. Schematic diagram of the parallel micro flow channel structureįig. Physical dimensions for the straight channel fuel cell sectionįigure 1. More recently, CFD and improved transport models have allowed the development of increasingly more realistic computational models, accounting for fluid, thermal and electrochemical transport, complex three-dimensional geometries including flow and cooling channels, and two-phase transport. The first applications of CFD methods to fuel cells focused on two-dimensional models, and. More detailed analysis of the multiple transport and electrochemical mechanisms requires the use of numerical models (CFD). However, they do not provide insight into the underlying transport and electrochemical phenomena that occur inside the fuel cells. were among the first to use the empirical equation to analyze their experimental polarization results. The model based on ohm’s low and Butler-Volmer (or Tafel) equation is the first kind of model which describes the performance of the PEM fuel cell, Ticianelli et al. The difficulties related to the fuel cell systems experimental environment have stimulated efforts to develop models that could enable simulation and prediction of multi-dimensionally coupled transport of reactants, heat and charge spies. Introduction PEMFC (Proton Exchange Membrane Fuel Cell) using very thin polymer membrane has been considered as a promising candidate of future power sources for transportation and residential applications.
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