Unsteady Performance of a PEMFC System Including Autothermal Methane Reforming

Abstract

A zero-dimensional, dynamic model of a PEM fuel cell with an autothermal methane reformer section is generated. In the model, reformer consists of three reactors for the autothermal steam reforming, the water gas shift, and the selective oxidation. Physical approaches are favored over empirical modeling equations in order to describe the relevant transport phenomena. Thus, in spite of the low order modeling, only physical parameters are required for the input. The aim of the model is the calculation of the cell voltage for a given set of geometrical and thermodynamic data including the current density. The fuel cell water management is modeled with equations for the water transport through the membrane by electro-osmotic drag and diffusion as well as the membrane humidity. Flooding due to liquid water content and dehydration of the membrane is simulated dynamically with this model. These critical conditions are identified by the cell voltage. Due to pressure feedback, dynamic simulations show partial pressure fluctuation in the reformer reactors caused by load changes of the fuel cell.