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The quest for achieving more efficient gas turbine engine systems (GTESs) has led the researchers to try getting into many new dimensions of research. Simple Brayton cycle-based GTESs were coupled with recuperators, regenerators and reheaters to avoid/recoup heat energy from being wasted and these were designated as complex GTESs. Multistage compression (multi-casing) in axial compressors and multistage (two-cylinder) expansions in turbines paved the path to optimize the plant design for greater thrust to weight ratio and greater efficiency of the GTESs. Since the increase in efficiency of any power plant is directly or indirectly related to temperatures at which the plant cycle is being operated, this thermodynamic constraint had led to the development of high temperature materials such as single crystal nickel-based superalloys.

In the present scenario, when the non-conventional energy resources are still under development stage for their full potential as a source of energy for our fast growing population, gas turbines are one of the most promising power generation technologies. The gas turbine based power utilities are also gaining acceptance across globe, because of increase in extraction of natural gas. Further reduction in the price of natural gas would also result in the number of gas turbine units installed across globe and thus it is important to carry out the environmental analysis of gas turbine based utilities. The gas turbines are employed in power generation in industries, aircrafts and marine propulsion units. The present exercise carries out thermodynamic performance analysis i.e. energy, exergy and emission performance analysis of an air-craft gas turbine. The gas turbine blades of present cycle are assumed to be cooled by air-film blade cooling technique.

Exergy analysis provides appropriate information for improvement of thermodynamic efficiency of the system focusing on system components with maximum exergy destruction. But this method lacks in showing the mutual interaction between system components on cycle performance. Hence an advanced approach i.e. Advanced Exergy Analysis’ has been adopted and discussed in present paper. Advanced exergy analysis of LM2500+, a marine gas turbine cycle adopting air-film blade cooling techniques has been reported. The advanced exergy analysis primarily focuses on categorizing the irreversibility of process components. Advanced exergy analysis identifies exergy destruction based on two different aspects: first identifying source of irreversibility and other being minimization of this irreversibility. Thus, advanced exergy analysis splits exergy destruction into endogenous and exogenous exergy destruction as well as avoidable and unavoidable exergy destructions.

Cogeneration involves simultaneous production of both thermal energy as well as electrical energy from a single energy conversion system. The thermal energy produced by the system is generally in the form of steam and generally used for process heating purposes. Marine gas turbine that provide propulsive power also have thermal energy in it exhaust gas stream which can be further be used to generate steam for process heating applications. Gas turbine blade cooling is critical to reliable operation of gas turbine based power utilities. A thorough literature review suggests that air-film cooling is one of the most widely used blade cooling techniques. The present study adopts few previously developed air-film cooling based gas turbine blade cooling models (without considering radiative heat transfer) and compare them with a proposed gas turbine model (which consider radiative heat transfer to gas turbine blade surface).

Air-film cooled gas turbine is widely used in aero-derivative gas turbines. The present paper reviews previously developed air-film blade cooling models. The article further proposes a new blade cooling model for estimating blade coolant mass fraction which takes into account the effect of radiative heat transfer from hot flue gases to aero-derivative gas turbine blade surface. Various possibilities to achieve enhanced performance from aero-derivative gas turbine have been enumerated namely effect of advanced design philosophies, thermal barrier coatings, advancement in blade material. Also adoption of advanced design philosophies such as 3-D CFD would lead to improved component design. Further use of advanced blade material specifically for gas turbine blade application including single-crystal blade, directionally solidified blade material being nickel-chrome-molybdenum alloys may be explored.