Modelling of a PEM Fuel Cell System with Propane ATR Reforming

Proton exchange membrane fuel cells (PEMFCs) are promising power sources not only for electric vehicles, but also for portable and stationary applications. In this paper, a 5 kW PEMFC system, suggested for domestic power applications with propane autothermal reforming, is modelled with PRO/II® from SIMSCI. When the fuel cell is operated at 2 atm, 80 °C, a hydrogen conversion of 0.75 and at an air stoichiometry 3.0, with the energies of the compressor and expander coupled with a 75% adiabatic efficiency, the system efficiency is calculated to be 34.8%. Different operating pressures and temperatures are studied; lower system efficiency is shown at higher pressure, lower temperature, and greater air stoichiometry. The simulation shows a significant drop in system efficiency for a lowered compressor and expander adiabatic efficiency. With an increase in this value from 50% to 85%, the system efficiency increases from 23.1% to 40.6%. The simulation reveals that it is critical to design special compressors and expanders for fuel cells with higher adiabatic efficiencies so that higher system efficiency can be achieved.