Modelling of an HTPEM-based micro-combined heat and power fuel cell system with methanol

A fuel cell-based combined heat and power system using a high temperature proton exchange membrane fuel cell has been modelled. The fuel cell is fed with the outlet hydrogen stream from a methanol steam reforming reactor. In order to provide the necessary heat to this reactor, it was considered the use of a catalytic combustor fed with methanol. The modelling aims to fit the hydrogen production to the demand of the fuel cell to provide 1 kW(e), maintaining a CO concentration always lower than 30,000 ppm. A system with 65 cells (45.16 cm(2) cell area) stack operating at 150 degrees C and hydrogen utilization factor = 0.9 (with O-2/methanol ratio = 2 at combustor; H2O/methanol ratio = 2 and temperature = 300 degrees C at reformer) needed a total methanol flow of 23.8 molh(-1) (0.96 L h(-1)) to reach 1 kW(e), with a system power efficiency (LHV basis) ca. 24% and a CHP efficiency over 87%. The ability to recycle the non-converted hydrogen from the fuel cell anode to the combustor and to use the heat produced at the fuel cell for obtaining hot water increased the global energy efficiency. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.