Energy and exergy analysis of steam cooled reheat gas–steam combined cycle

• Published in: Applied thermal engineering Vol. 27; no. 17; pp. 2779 - 2790
• Main Authors: Sanjay, Y., Singh, Onkar, Prasad, B.N.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.12.2007; Elsevier
• Subjects: Applied sciences; Closed-loop-steam-cooling; Energy; Energy and exergy analysis; Energy. Thermal use of fuels; Engines and turbines; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Heat transfer; Reheat gas turbine; Theoretical studies. Data and constants. Metering; Closed-loop-steam-cooling; Reheat gas turbine; Energy and exergy analysis; Blades; Compressor; Water vapor; Modeling; Air cooling; Combustion chamber; Combined cycle; Exergy analysis; Thermal efficiency; Gas turbine
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2007.03.011

This paper deals with parametric energy and exergy analysis of reheat gas–steam combined cycle using closed-loop-steam-cooling. Of the blade cooling techniques, closed-loop-steam-cooling has been found to be superior to air-film cooling. The reheat gas–steam combined cycle plant with closed-loop-steam-cooling exhibits enhanced thermal efficiency (around 62%) and plant specific work as compared to basic steam–gas combined cycle with air-film cooling as well as closed-loop-steam cooling. Further, with closed-loop-steam-cooling, the plant efficiency, reaches an optimum value in higher range of compressor pressure ratio as compared to that in film air-cooling. It has also been concluded that reheat pressure is an important design parameter and its optimum value gives maximum plant efficiency. Component-wise inefficiencies of steam cooled-reheat gas–steam combined cycle based on the second-law-model (exergy analysis) have been found to be the maximum in combustion-chamber (≈30%), followed by that in gas turbine (≈4%).