The Effect of the Fuel-Cell Unit Size on the Efficiency of a Fuel- Cell-Topped Rankine Power Cycle

Abstract

Dunbar, Lior and Gaggioli (1991) proposed a configuration of a fuel-cell-topped electrical Rankine power generating station and analyzed its performance. That study revealed that the fuel-cell topping improved plant efficiency to values up to 62 percent, versus the conventional plant efficiency of 41.5 percent. This work lays the foundation for a thermoeconomic analysis of such systems by relating exergy consumption to fuel-cell unit size, as follows: 1) the relationship between system efficiency (and hence fuel consumption) and fuel-cell unit size is presented for a number of fuel-cell operating conditions; 2) the relationship between fuel flow rate and fuel-cell unit size is shown; and 3) the exergetic effects of the major plant components are discussed as a function of fuel-cell unit size. The results reveal that specific fuel consumption may be reduced by as much as 32 percent when incorporating fuel-cell units into electrical power plants.