Empirical correlations for the performance of a PEFC considering relative humidity of fuel and oxidant gases

Abstract

The growing energy demand and the impact of polluting gases lead to the necessity of alternative energy sources and conversion energy devices. Fuel cells (FCs) appears as a suitable solution for facing the mentioned issues. Predicting the behavior of a polymer electrolyte fuel cell (PEFC) under different conditions represents a proper initial step to solve the several issues, e.g., aging water balance problems, which occur inside the cell during the energy conversion process. Understanding microstructural impacts of the diffusion media, water management issues of FCs or the impacts of the inlet reactant gases to the cell represent some of the processes that have to be analyzed to improve the efficiency and behavior of FCs.The current study aims, based on experimentally collected data, to propose empirical correlations that describe and predict the performance of a PEFC. The single cell considered in this study corresponds to a single PEFC with a Nafion® 112 membrane as electrolyte and with an effective area of 25 cm2. Relative humidity as a function of the reactive inlet gas temperature, as well as the power and the current density as a function of the cell/reactant gas temperature gradient are analyzed. In addition, correlations for power and current density as a function of the relative humidity (RH) have been proposed. Our correlations are obtained for an operating voltage of 0.6 V. It was shown a strong correlation between the power and current densities with the RH since the membrane conductivity depends mainly on the water content. The PEFC behavior was evaluated at different RHs. The results show big losses of operating power and current densities, as well as an increment of the resistance of the membrane when it operates at low RH.