Numerical simulation of proton exchange membrane fuel cell

This chapter presents general mathematical models and numerical simulation for proton exchange membrane fuel cell (PEMFC) to evaluate the effects of various designs and operating parameters on the PEMFC performance. Both one and two-dimensional models are presented; the advantages and weaknesses of using one-dimensional and two-dimensional models are discussed in detail. Subsequently, a general three-dimensional model is developed and described in detail. This threedimensional general model accounts for electrochemical kinetics, current density distribution, hydrodynamics, and multi-component transport. It starts from basic transport equations including mass conservation, momentum equations, energy balance, and species concentration in different elements of the fuel cell sandwich, as well as the equations for the phase potential in the membrane and the catalyst layers. These governing equations are coupled with chemical reaction kinetics by introducing various source terms. It is found that all these equations are in a very similar form except the source terms. Based on this observation, all the governing equations can be solved using the same numerical formulation in a single domain without prescribing the boundary conditions at interfaces between different elements of the fuel cell. Detailed numerical formulations are presented in this chapter. Various parameters, such as velocity field, local current density distribution, species concentration variation along the flow channel, under various operation conditions are computed by solving these governing equations in a single domain consisting of gas channel, catalyst layer and membrane. The performance of the PEMFC affected by various parameters such as temperature, pressure, and the thickness of the membrane is investigated. The numerical results are further validated with experimental data, which are available in the literature. This general three-dimensional model can be used for the optimization of PEMFC design and operation. It can also serve as a building block for the modeling and understanding of PEMFC stacks and systems. www.witpress.com, ISSN 1755-8336 (on-line) WIT Transactions on State of the Art in Science and Engineering, Vol 10, © 2005 WIT Press doi:10.2495/1-85312-840-6/06 216 Transport Phenomena in Fuel Cells