Configuration design and parametric optimum selection of a self-supporting PEMFC

Abstract

A new theoretical model of the thermally self-sustained proton exchange membrane fuel cell (PEMFC) is proposed, where syngas is preheated by the heat from the reaction in the fuel cell and water gas shift reactions, and the endothermic steam reforming process of methane is maintained by absorbing a part of the combustion heat of residuary hydrogen from the fuel cell. Based on some thermal equilibrium equations, the temperatures of syngas and combustion product in different stages are calculated, respectively. The power density and conversion efficiency of the PEMFC are derived. The influences of the molar flow rate of syngas, hydrogen utilization ratio, and working temperature of the fuel cell on the property of the PEMFC are discussed detailedly. In the rational range of the operating temperature, the maximum power densities and corresponding efficiencies are calculated, the optimum values of several key parameters at the maximum power densities are determined, and the optimal selection criteria of molar flow rate of syngas and other parameters are provided.