Title: Thermodynamic modelling of three-stage combined cycle power systems utilising ammonia-water mixture as a working fluid in bottoming cycle

Authors: Amin Momeni; Hossein Shokouhmand

Addresses: School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran 1439955961, Iran ' School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran 1439955961, Iran

Abstract: In this study, two three-stage combined power cycles with ammonia-water mixture in bottoming cycle are introduced; one with variable ammonia fraction and the other with constant ammonia fraction. Energy and exergy analyses are carried out and optimal parameters of the proposed cycles are compared with the conventional power cycles. The second law efficiency of three-stage cycles with variable and constant ammonia fraction are 4.71% and 5.15% higher than steam-gas combined power cycle, respectively. Exergy flow diagram for each cycle is presented and exergy destruction of all components is investigated. Results quantitatively highlight the thermodynamic advantages of the proposed cycles in comparison with the conventional cycles. Three-stage cycle with constant ammonia fraction has the best performance in comparison with the others.

Keywords: exergy analysis; energy analysis; ammonia-water combined cycle; exergy destruction; performance; thermodynamic modelling; working fluids; bottoming cycle; ammonia; water.

DOI: 10.1504/IJEX.2014.061031

International Journal of Exergy, 2014 Vol.14 No.3, pp.320 - 340

Received: 18 Sep 2012
Accepted: 24 Apr 2013
Published online: 02 Mar 2015 *

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