Simulation and Analysis of Transient Fuel Cell System Performance Based on a Dynamic Reactant Flow Model

Abstract

Fuel cell stack systems are under intensive development by several manufacturers since they complement heat engines and reduce the ubiquitous dependence on fossil fuels and thus have significant environmental and national security implications. To compete with ICE engines, however, fuel cell system must operate and function at least as well as conventional engines. Transient behavior is on of the key requirements for the success of fuel cell vehicles. The fuel cell system power response depends on the air and hydrogen feed, flow and pressure regulation, and heat and water management. During transient, the fuel cell stack control system is required to maintain optimal temperature, membrane hydration, and partial pressure of the reactants across the membrane in order to avoid degradation of the stack voltage, and thus, efficiency reduction. In this paper, we developed a fuel cell system dynamic model suitable for control study. The transient phenomena captured in the model include the flow characteristics and inertia dynamics of the compressor, the manifold filling dynamics (both anode and cathode), and consequently, the time-evolving reactant partial pressures, and membrane humidity. The effects of varying oxygen concentration and membrane humidity on the fuel cell voltage were included. Simulation results are presented to demonstrate the model capability.