WHEC 16 / 13-16 June 2006 – Lyon France 1/11 Sensitivity analysis of the design parameters of cathode side of the bipolar plates José Javier Martínez a , Felipe Rosa Iglesias b , Fco Javier Pino c a AICIA, Edificio ESI, Camino de los Descubrimientos s/n, 41092 Sevilla, Spain, jjms@us.es b Instituto Nacional de Técnica Aeroespacial, Ctra San Juan del Puerto-Matalascañas km 33, 21130 Mazagón (Huelva), Spain, rosaif@inta.es c Escuela Superior de Ingenieros, Camino de los Descubrimientos s/n, 41092 Sevilla, Spain, fjp@us.es ABSTRACT: Bipolar plates are one of the most important devices in PEMFC due to numerous functions that it performs. Hence, bipolar plates must be designed to fulfil all these functions. A sensibility analysis of some geometrical parameters of this component is made. The effect of varying the values of these parameters on the performance of a PEMFC is studied. The procedure is to simulate different models with different geometrical features using FLUENT 6.1 software. The models are focused on the cathodic compartment of a bipolar plate. In this way, water management plays an important role as comparison parameter. Lower pressure drop and more homogeneity of reactant over the interface channel-GDL were resulted with the increase of the channel dimensions; the removed quantity of liquid water was higher with smaller depth and width of channel. The best flow field design for cathode bipolar plate for the comparison criteria of this work was the ‘pin’ type configuration and it was obtained that the performance improves with the increasing of inlets and outlets in the plate. KEYWORDS: Bipolar plate, geometry, cathode, PEMFC. 1 INTRODUCTION The numerous functions that the bipolar plates carry out in the operation of the fuel cells make them a very important element in the optimisation of the stack. The following functions can be highlighted: supply the reactant gases through the flow channels to the electrodes and serve the purpose of electronically connecting one cell to another in the electrochemical cell stack. These plates also provide structural support for MEAs and prevent leakage of gases. They are also responsible devices for water management. Besides, the bipolar plates also facilitate heat management in absence of cooling plates. Hence, these plates have to be designed to fulfil those functions in the best possible way. The objective of this paper is to analyse how the geometrical design parameters of a bipolar plate have influence in the performance of a PEMFC. Several simulations are done in order to compare different three-dimensional models of bipolar plates. The simulating tool used is FLUENT 6.1. The cathode is one of the most critical components of the PEMFC due to a slow kinetics of the oxygen reductions half-reaction. Hence, the present study focuses on the cathodic compartment. Investigations related to the cathode side have given important results, for example, higher stoichiometric flow rate resulted in more uniform current densities along the channel resulting in better cathode performance. This performance was found to decrease with increasing inlet stream humidity. Higher temperatures resulted in non-uniform current density distribution along the length of the channel and higher average performance of the cathode [1]. According to this researching line, A lot of studies about interdigitated fuel/air distributor appear in bibliography. The use of this technology implies a better water removal since they promote convective flow. Besides, its utilisation increases the current density and the global performance. However larger pressure drop appear [2].