| Abstract: | 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. |
