Int. J. Exergy, Vol. 9, No. 4, 2011 435 Copyright © 2011 Inderscience Enterprises Ltd. Energy and exergy analyses of a supercritical power plant Ebrahim Hajidavalloo* and Amir Vosough Mechanical Engineering Department, Shahid Chamran University, Ahvaz, Iran Fax: +98-611-3336642 E-mail: hajidae_1999@yahoo.com E-mail: vosough_amir@yahoo.com *Corresponding author Abstract: Energy and exergy efficiencies of a supercritical power plant have been studied in this paper. The effect of ambient weather condition was considered on the condenser pressure. It was shown that high ambient temperature has more adverse effect on the exergy efficiency than the energy efficiency. As ambient temperature increases, the exergy efficiency of the boiler, condenser, heaters and feed water pump decrease, while the exergy efficiency of the turbine improves slightly. The analysis showed that exergy efficiency of the supercritical boiler is considerably higher than the conventional boiler but it is still the main source of total irreversibility. Keywords: supercritical power plant; irreversibility; exergy efficiency; condenser pressure. Reference to this paper should be made as follows: Hajidavalloo, E. and Vosough, A. (2011) ‘Energy and exergy analyses of a supercritical power plant’, Int. J. Exergy, Vol. 9, No. 4, pp.435–452. Biographical notes: Ebrahim Hajidavalloo is an Associate Professor at the Mechanical Engineering Department of Shahid Chamran University of Ahvaz. He has completed his PhD from Dalhousie University in Canada and since then is working in current position. Amir Vosough has completed his MSc degree from Mechanical Engineering Department of Shahid Chamran University of Ahvaz. He is currently Instructor in the Department of Mechanic, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran. 1 Introduction Improving the performance of power plant is a never ending subject. In addition to energy analysis which elaborates on the quantity of efficiency, exergy analysis has been used to indicate the performance quality of the power plant. In exergy analysis, the second law of thermodynamics is used for furthering the goal of more efficient energy-resource use. Exergy analysis enables to accurately identify the locations, types and magnitudes of wastes and losses to determine the meaningful efficiency (Dincer and Rosen, 2007). Summaries of the evolution of exergy analysis are provided by Kotas