Water Activity Control of PEMFC Using EMR and Inversion Methodology

This paper describes a method for water activity control in a Proton Exchange Membrane fuel cell using a new graphic tool of energy systems called Energy Macroscopic Representation (EMR). This methodology allows the interconnecting models of the fuel cell voltage, power, and Relative Humidity (RH) as a function of operating variables such as current, pressure, temperature, the flow of hydrogen, oxygen, and water. The validation of the simulation results illustrates the influence of relative humidity on the fuel cell behavior. In addition, these variables are adjusted taking into account of relative humidity in order to reach a better performance of the system. For this reason, a control method based on inversion, namely the Maximum Control Structure (MCS) is used to make this energy source more accessible and to avoid the disadvantages of over flow and drying case in order to achieve a suitable relative humidity needed for the implementation of this fuel cell.