A simplified dynamic simulation model (prototype) for a stand-alone Polymer Electrolyte Membrane (PEM) fuel cell stack

Abstract

The ever increasing demand for electrical energy and the rise in the electricity prices due to the recent instability of the oil prices in addition to the degrading of the air quality resulting from the emissions of the existing energy conversion devices has intensified research into alternative renewable sources of electrical energy. In this paper a dynamic electrochemical model is developed to simulate a polymer electrolyte membrane fuel cell (PEMFC) system to allow the development and improvement of electrical energy generation systems using this new promising technology. Although other models have been produced but most of these capture the fuel cell (FC) steady state behaviour by estimating its voltage for a particular set of operating conditions. The proposed model allows the incorporation of effects of different dynamic conditions in load current, pressure of input reactant gases, fuel cell operating temperature as well as the mass/heat transfer transient features in the fuel cell body. Its capability of predicting transient dynamics will also prove useful when attempting to develop a control strategy. The proposed model strength is modularizing the fundamental thermal- physical behaviour of a fuel cell and developing a modular block that can be used as a part of any other schematic solution required for fuel cells' study. The developed modular block (prototype) exhibits most of the basic fuel cell properties and incorporates essential physical and electrochemical processes that happen along its operation, allowing its' easy moderation for modelling other fuel cells with different cell parameters and allow investigation of their behaviour for any operating or design configuration. The prototype can be useful in future in studying the integration of fuel cells into distribution power systems. The proposed modular block is implemented in SIMULINK and is verified by generating model results and comparing this to benchmark results for a Ballard NEXAtrade Power module. The proposed model was also compared to another simplified model; sample results for a Ballard V PEMFC were generated for both models indicating that the developed model is more accurate in simulating the fuel cell especially at high operating current densities.