Modelling and Examining Open Circuit Voltage for PEM Fuel Cells

Fuel cells are ultimately one of the best promising devices that convert the potential energy in the reactants into the electrical energy after steps of sequential electrochemical processes with no hazards up on the environment. This paper presents comprehensive derivation and understanding of the electrochemical reaction for Polymer Electrolyte Membrane Fuel Cell (PEMFC) in terms of parameters and surrounding impacts, starting from the initial phenomena of splitting hydrogen molecule to the final mathematical model of open circuit voltage for PEMFC. The open circuit voltage has been derived and modelled for two operational conditions, when the output water from fuel cell is in liquid state, and when the output water is in state of vapour. Examining and analysing OCV under different operational temperature and pressure. Using pure oxygen instead of air has very small impact on increasing the OCV by 1% under same operational temperature and pressure; hence the use of pure oxygen is no longer defensible motive as this will increase the weight and cost of the system.