Design of a domestic high temperature proton exchange membrane fuel cell cogeneration system : modelling and optimisation

Abstract

Fuel cells are among power generation technologies that have been proven to reduce greenhouse gas emissions. They have the potential of being one of the most widely used technologies of the 21st century, replacing conventional technologies such as gas turbines in stationary power supplies, internal combustion engines in transport applications and the lithium-ion battery in portable power applications. This research project concentrates on the performance analysis of a micro-cogeneration system based on a high temperatureproton exchange membrane (HT-PEM) fuel cell through modelling and parametric analysis. A model of a 1kWe micro-cogeneration system that consists of a HT-PEM fuel cell, a methane steam reformer (MSR) reactor, a water-gas-shift (WGS) reactor, heat exchangers and an inverter was developed. The model is coded/implemented in gPROMS Model Builder, an equation oriented modelling platform. The models predictions for the HTPEM fuel cell, MSR and WGS, and the whole system were validated against experimental and numerical results from literature. The validation showed that the HT-PEM fuel cell model was able to predict the performance of a 1kWe fuel cell stack with an error of less than 6.4%. The system model is rstly used in a thermodynamic analysis of the fuel processor for a methane steam reforming process and investigated in terms of carbon monoxide produced. The combustor fuel and equivalence ratios were shown to be critical decision variables to be considered in order to keep the carbon monoxide from the fuel processor at acceptable levels for the fuel cell stack.