Thermodynamic Evaluation of Gas/Steam Combined Cycle Performance With Active Controlled Film Cooling
Efficiency of gas turbine cycles can be improved by increasing the turbine inlet temperature. Advanced gas turbines operate at temperatures far above their material limitations to increase thermal efficiency. So, film cooling technique is mostly used to protect the gas turbine blades from high temperature gases. The film cooling jets penetrate into the mainstream gas and form a thin film for protecting the blade surfaces from hot gas. However, due to lift-off effect the attachment of the coolant jet to the blade wall, downstream, becomes crucial. Plasma actuator strategy proposed by some of the researchers may be considered to be utilized, to maintain the attachment of jet with the blade-wall and improve the film cooling effectiveness. In this article the effect of a proposed active controlled film cooling technique using plasma actuator strategy on thermodynamic performance of gas/steam combined cycle has been evaluated and compared with the combined cycle employing simple film cooling technique as well as with advanced transpiration cooling technique of gas turbine blades. Reduced coolant requirement and hence reduced dilution losses with active controlled film cooling as compared to simple film cooling, results in improved topping as well as bottoming cycle performance. It is seen that the combined cycle efficiency with active film cooling is comparable to the transpiration cooled combined cycle efficiency. At a turbine inlet temperature (TIT) of 1900 K, the combined cycle efficiency with active film cooling strategy is higher by 0.5% than that with simple film cooling.
Chiesa, P. and Macchi, E. (2004), “A thermodynamic analysis of different options to break 60% electric efficiency in combined cycle power plants,” Journal of Engineering for Gas Turbines and Power, 126, 770-785.
Chin, W.W. and El-Masri, M.A. (1987), “Exergy analysis of combined cycles: part 2 – Analysis and optimization of two-pressure steam bottoming cycles,” Journal of Engineering for Gas Turbines and Power, 109, 237-243.
Horlock, J.H., Watson, D.T., Jones T.V. (2001), “Limitations on gas turbine performance imposed by large turbine cooling flows,” Journal of Engineering for Gas Turbines and Power, 123, 487-494.
Kumar, S. and Singh, O. (2010), “Thermodynamic performance evaluation of gas turbine cycle with transpiration cooling of blades using air vis-à-vis steam” Proc. IMechE, Part A: J. Power and Energy, 224 (A8), 1039-1047. DOI 10.1243/09576509JPE964
Kumar, S. and Singh, O. (2011), “Performance evaluation of transpiration-cooled gas turbine for different coolants and permissible blade temperatures considering the effect of radiation,” Proc. IMechE, Part A: J. Power and Energy, 225, 1156-1165. DOI 10.1177/0957650911404305.
Kumar, S. and Singh, O. (2012), “Effect of gas/steam turbine inlet temperatureson combined cycle having air transpiration cooled gas turbine,” J. Inst. Eng. India Ser. C, 93(4), 297-305. DOI 10.1007/s40032-012-0046-9.
Najjar, Yousef S.H. et.al. (2004), ”Comparative performance of combined gas turbine systems under three different blade cooling schemes,” Applied Thermal Engineering, 24, 1919-1934.
Polezhaev, J., (1997), “The transpiration cooling for blades of high temperatures gas turbine,” Energy Conversion Management, 38, 1123-1133.
Sanjay, Singh, O., Prasad, B.N., (2008), “Influence of different means of turbine blade cooling on the thermodynamic performance of combined cycle,” Applied Thermal Engineering, 28, 2315-2326.
Sanjay Kumar and Singh, O. (2008), “Thermodynamic evaluation of different gas turbine blade cooling techniques,” IEEE Xplore Conference Proceedings-Second International Conference on Thermal Issues in Emerging Technologies, ThETA ‘08’; 237-244 (Digital Object Identifier 10.1109/THETA.2008.5167172).
Srinivas, T., Gupta, A.V.S.S.K.S., Reddy, B.V. (2007), “Parametric simulation of steam injected gas turbine combined cycle,” Proc. IMechE, Part A: J. Power and Energy, 221, 873-882.
Wang, C.C. and Roy, S., (2009), “Active cooling of turbine blades using horseshoe plasma actuator.” 47th AIAA Aerospace Sciences Meeting and Exhibit, Orlando, Florida, 5-8 January, AIAA-2009-0679.