Exergy analysis for a gas turbine cogeneration system

A general exergy balance equation that is applicable to any component of thermal systems has been formulated in this study. One of distinct features of this formulation is that the exergy involved in the component of any thermal system can be decomposed into exergy flows, entropy production flows, and the appropriate exergy rate terms such as fuel and available work. The exergy analysis based on this equation permits one to predict the thermal efficiency of the system, the exergy destruction in each component as well as the mass flow rate, the composition, and the temperature of the exhaust gases. The authors have examined the performance of a 1,000 kW gas turbine cogeneration system when it is operated at part and full-load conditions through this analysis. They have also tested the effect of the inlet air temperature and the relative humidity of the inlet air on the performance of the system. The predicted values of the performances for the system have been compared with the actual performance data provided by the gas turbine manufacturer. It has been found that the measured data of net power and the properties of exhaust gases are in good agreement with calculation ones, differing by lessmore » than 3%. The exergy balance equation may be utilized in the exergoeconomic analysis to estimate the production costs depending on various input costs in a gas turbine cogeneration system.« less