Flow-Field Study in a Microjet PEM Fuel Cell

Microjets have been implemented into a PEM fuel cell in an attempt to achieve even distribution of reactants and passive cooling of the fuel cell unit and a preliminary investigation of this application has yielded positive results. Unlike conventional reactant supply, the reactant microjets impinge on the back side of the flow field plate before wrapping around and traversing the flow field channels where they are involved in electrochemical activity. However, it was observed that the fuel cell was subject to significant flooding, which limited its continuous operation. This paper discusses the results from an experimental study that has been carried out in an attempt to reduce or eliminate the occurrence of flooding through the use of two different flow-field configurations. Measurements of these flow field configurations, identified as MJFC I and MJFC II, are presented here. MJFC I, the first generation prototype, uses a variant of parallel flow field while MJFC II, the second generation prototype, uses multiple independent serpentine flow field channels. For similar operating conditions, characteristic curves obtained showed that MJFC I is susceptible to flooding while MJFC II has superior water management capability. Secondary tests using Electrode Impedance Spectroscopy confirm these findings.