Second Law-Based Assessment of Combined Cycle Power Plant

Abstract

Energy is the main driving force to raise the economy of a nation. The demand for energy grows proportionally with the population of the country. The combined cycle technology is one of the most efficient and widely used technologies for power generation these days if natural gas is utilized as fuel. To meet the ever-growing electric energy demand with decreasing fossil fuel resources, it is necessary to further improve the performances of power generation systems. This can be done either by installing new plants with improved technology or by reducing losses within the existing plants. The present work investigates the thermodynamic performance of the existing Brayton-Rankine power plant currently in operation in India with actual operating data. Energy and exergy analyses of the said plant have been carried out through a computational model coded in MATLAB taking into consideration the important aspect of identifying the places and components of maximum thermodynamic losses which is the originality in the present work. Using the combustion energy of the fuel, which is 759.290 MW, the theoretical value of net power generated, overall thermal efficiency and exergetic efficiency of the plant is estimated to be 317.381 MW, 41.79 %, and 40.19 % respectively. The combustion chambers of the two gas turbines are turned out to be the most irreversible component with the maximum percentage of exergy destruction (14.9 %).