IDEAL CYCLE EVALUATION OF STEAM AUGMENTED GAS-TURBINES

A wide range of air-standard Brayton and modified-Brayton power cycles are evaluated to determine their second-law efficiencies and their vo lume flows per unit output. A cycle with reheating is chosen for furth er analysis on the basis of its potential for high efficiency through exploitation of its exhaust availability (exergy) and its low volume r ates. This exploitation can be had either through a conventional Ranki ne bottoming cycle, or through injection of the bottoming cycle steam into the Brayton turbine. The Rankine bottoming cycle is superior with respect to second-law efficiency; the cycle augmented by injected ste am is superior with respect to volume flows. Examination of irreversib ilities illuminates the reasons for the better efficiency of the Ranki ne bottoming cycle alternative.