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Exergy Based Performance Analysis of a Gas Turbine Unit at Various Ambient Conditions

Authors: Idris A. Elfeituri

Abstract:

This paper studies the effect of ambient conditions on the performance of a 285 MW gas turbine unit using the exergy concept. Based on the available exergy balance models developed, a computer program has been constructed to investigate the performance of the power plant under varying ambient temperature and relative humidity conditions. The variations of ambient temperature range from zero to 50 ºC and the relative humidity ranges from zero to 100%, while the unit load kept constant at 100% of the design load. The exergy destruction ratio and exergy efficiency are determined for each component and for the entire plant. The results show a moderate increase in the total exergy destruction ratio of the plant from 62.05% to 65.20%, while the overall exergy efficiency decrease from 38.2% to 34.8% as the ambient temperature increases from zero to 50 ºC at all relative humidity values. Furthermore, an increase of 1 ºC in ambient temperature leads to 0.063% increase in the total exergy destruction ratio and 0.07% decrease in the overall exergy efficiency. The relative humidity has a remarkable influence at higher ambient temperature values on the exergy destruction ratio of combustion chamber and on exergy loss ratio of the exhaust gas but almost no effect on the total exergy destruction ratio and overall exergy efficiency. At 50 ºC ambient temperature, the exergy destruction ratio of the combustion chamber increases from 30% to 52% while the exergy loss ratio of the exhaust gas decreases from 28% to 8% as the relative humidity increases from zero to 100%. In addition, exergy analysis reveals that the combustion chamber and exhaust gas are the main source of irreversibility in the gas turbine unit. It is also identified that the exergy efficiency and exergy destruction ratio are considerably dependent on the variations in the ambient air temperature and relative humidity. Therefore, the incorporation of the existing gas turbine plant with inlet air cooling and humidifier technologies should be considered seriously.

Keywords: Destruction, exergy, gas turbine, irreversibility, performance.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1132266

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References:


[1] Electricity Company in Libya, ‘Electricity Generation in Libya’, Planning department, technical report, 2011.
[2] Bolland Olav, Thermal Power Generation, Department of Engineering, Process Engineering, NTNU, 2010.
[3] Szargut J., Morris D. R., and Steward F. R., Exergy Analysis of Thermal, Chemical and metallurgical process, Hemisphere, New York, 1988.
[4] Gaggioli R. A. et al., “Pinpointing the Real Inefficiencies in Power Plants and Energy Systems,” Proc. American Power Conference, 37, USA, 1975.
[5] Moran M. J., and Sciubba E., “Exergy Analysis Principle and Practice”, ASME J. Eng. Gas Turbines Power, vol. 116, pp. 285-290, 1994.
[6] Balli O., Aras H. and Hepbasli A., “Exegetic Performance Evaluation of a Combined Heat and Power (CHP) System in Turkey,” Int. J. Energy Research, vol. 31, no. 9, pp. 849–866, 2007.
[7] Song T. W. et al., “Exergy Based Performance Characteristics of the Heavy Duty Gas Turbine in Part Load Operation Conditions,” Exergy Int., vol.2, pp. 105-112, 2002.
[8] Aklilu et al., “Exergy Based Performance of a Gas Turbine at Part Load Conditions,” Journal of App. Sc., vol.11, no. 11, pp. 1994-1999, 2011.
[9] Oh S. et al., “Exergy Analysis for a Turbine Cogeneration System,” ASME J., Eng. Gas Turbines Power, vol. 118, pp. 782-791, 1996.
[10] Abam F. et al., “The Effect of Ambient Temperature on Components Performance of an In-service Gas Turbine Plant using Exergy Method,” Singapore J. of Scientific research vol. 1, pp. 23-37, 2011.
[11] Tara V. et al., “Exergy Analysis of Gas Turbine Power Plant”. Int. J. of Eng. Trends and Tech., vol. 4,pp. 3991-3993, 2013.
[12] Egware H. O. and Obanor A. I., “Exergy Analysis of Omotosho Phase 1 Gas Thermal Power Plant,” Int. J.of Energy power engineering, vol.295, pp.197-203, 2013.
[13] De Sa, S., Al Zubaidy, “Gas Turbine Performance at Varying Ambient Temperature,” Appl. Thermal Eng., vol. 31, pp. 2735-2739, 2011.
[14] Fallah M. G, “Effect of Ambient Temperature on the Thermodynamic Performance of a Combined Cycle,” J. of Eng. Research, Triply University, vol. 13, pp. 35-48, 2011.
[15] Hadik A. A., “The Impact of Atmospheric Conditions on Gas Turbine Performance, “Transactions of ASME, vol. 112, pp. 590-596, 1990.
[16] Bassem G., et al., “Performance of Gas Turbine Co-generation Power Desalting Plants under Varying Operating Conditions in Kuwait,” Heat Recovery Systems &CHP vol.10, no 3, pp. 243-253, 1990.
[17] Siemens Power Generation Co., Performance Curves for Sarir SGT5-PAC 4000F Gas Turbine Power Plant Under Ambient and Loading Conditions, Siemens Performance Data Catalogue 2010.
[18] Moran M. J., and Shapiro H. N., Fundamentals of Engineering Thermodynamics, 3rdEdn., John Wiley and Sons Inc., New York, 2006.
[19] Katos T., The Exergy Method in Thermal plant Analysis, Butterworths, London, 1985.
[20] Aklilu B T., Gilani S I., “Mathematical Modeling and Simulation of a Cogeneration Plant. Applied Thermal Eng. vol. 30, pp. 2545-2554, 2010.
[21] Na Zhang, Ruixin Cai, “Analytical Solutions and Typical Characteristics of Part Load Performance of a Single Shaft Gas Turbine and its Cogeneration,” Energy Conversion and Management, vol. 43, pp. 1323-1337, 2003.