The effect of fuel cell operating conditions on DIR-MCFC system selection

The use of natural gas and ‘direct internal reforming’ allows very simple molten carbonate fuel cell systems to be devised. The compositions and flow rates of the anode and cathode stack inlet and outlet gas flows can be described by five dimensionless system variables. These variables describe the total air flow, the cathode recycle, the overall fuel utilisation, the anode recycle, and the amount of steam addition. The equilibrium stability limits of carbon are presented and related to the system variables. A simplified stack model has been developed and a parametric analysis has been performed to determine the effect of the system variables on the stack performance. Two atmospheric pressure systems are presented which are suitable for combined heat and power applications of less than 1 MWe.