Search Results

Increasing in the turbine rotor inlet temperature improves the aviation gas turbine efficiency, while on the other hand, but also leads to a higher requirement for blade cooling air, which in turn reduces the gain in efficiency achieved by increasing temperature. Turbine rotor inlet temperature has been increasing with the entry of highly-efficient gas turbines have been developed for the last decades for the aviation market. Around one fifth of the compressed air is extracted from the compressor and is used for blade cooling purposes and is thus not used in the actual power/thrust generation process, which has a negative impact on the engine efficiency. For this reason, new cooling methods and hot-gas path component materials that will be compatible with these high temperature’s gases are among the areas being analyzed.

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.

Abstract The current global energy scenario demands for fuel efficient and cost effective thermal systems of energy conversion. It leads to investigation of techniques which can minimize the energy wastage and maximize the utilization of energy. In this regard the present paper proposes a configuration (LM2500+G4 marine engine manufactured by M/S GE Aviation for cogeneration application) for marine propulsion and cogeneration. The exhaust gas temperature of LM2500+G4 marine engine is around 800 K hence heat of this exhaust stream can be utilized to produce process steam for further use. In this particular work the aforesaid configuration has been exergoeconomically analyzed to predict the total cost rate (investment cost rate + fuel cost rate) of the system. The “Average Cost Theory” has been approached for the exergoeconomic analysis. The exergoeconomic analysis is the combined study of thermodynamic concepts and economic principles.

An “APU” (Auxiliary Power Unit) is a small gas turbine engine to provide supplementary power to an aircraft and is located at the tails of larger jets. APU generators provide auxiliary electrical power for running aircraft systems on the ground. Applications include powering environmental systems for pre-cooling or preheating the cabin, and providing power for crew functions such as preflight, cabin cleanup, and galley (kitchen) operation and long-haul airliners must be started using pneumatic power of APU compressor. The Honeywell 131-9A gas turbine APU has 440 kW shaft power and 90 kW electric generator consuming 120 kg fuel/hour. Hybrid power systems based on fuel cells are promising technology for the forthcoming power generation market. A solid oxide fuel cell (SOFC) is the perfect candidate for utilizing waste heat recovery. This case deals with waste heat recovery from fuel cell exhaust using Brayton cycle as bottoming cycle for additional power production.

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.

An “APU” (Auxiliary Power Unit) is a small gas turbine engine to provide supplementary power to an aircraft and is located at the tails of larger jets. APU generators provide auxiliary electrical power for running aircraft systems on the ground. Applications include powering environmental systems for pre-cooling or preheating the cabin, and providing power for crew functions such as preflight, cabin cleanup, and galley (kitchen) operation and long-haul airliners must be started using pneumatic power of APU compressor. The Honeywell 131-9A gas turbine APU has 440 kW shaft power and 90 kW electric generator consuming 120 kg fuel/hour. Here the traditional combustor of the APU is proposed to be replaced by a chemical-looping-combustion (CLC) system.

The integration of inlet air cooling to gas turbine based power utilities is a well accepted practice as this modification to the utility delivers superior utility performance. However, application of inlet-air cooling to drive turbines and specifically to marine mobility sector is rare in literature. Marine vessels are generally propelled by diesel engines, however large marine vessels specifically cruise ships and high speed naval vessels may have requirements of higher speeds and on-board power requirements which can fulfilled by gas turbine driving the propellers while on-board power needs can be met by steam turbine power generated from gas turbine exhaust heat. Such gas-steam combined cycles have the potential to become popular for high capacity marine vessels. The choice of gas turbine based combined cycle power plant for marine vessels in comparison to diesel engine powered vessel is also superior due to lower emission from the former.

The aim of this study is to investigate the overall performance (exergetic, exergoeconomic and exergoenvironmental) of CT7-7A turboprop engine manufactured by General Electric Aviation (GE Aviation) and currently used to power CN-235, a medium range transport aircraft. The investigation has been carried out using the thermoeconomic, sustainability and environmental damage cost analysis methods. The adopted turboprop engine has been investigated to observe the behaviour of various performance parameters, sustainability, emission parameters as well as cost parameters of engine. Due to ever increasing demand in air transport systems, focus has been on developing efficient and sustainable systems with lowest possible cost. In order to reduce cost & environmental effects of engine and at same time to acquire higher performance, it is necessary to understand the mechanism that can offer improvements in the engine operating and design parameters so that higher performance can be obtained.

This paper deals with effect of evaporative inlet air cooling on exergy and emission in basic gas turbine cycle. Inlet air cooled gas turbine based power plants are operational in various parts of the world. The article is an attempt to analyze thermodynamic and emission performance to these cycles. Rational efficiency of gas turbine for cooled inlet air at lower relative humidity is higher; also the exergy destruction in combustor is higher among all other components. For a fixed value of equivalence ratio, residence time, turbine-rotor-inlet temperature and two varying relative humidity effect of various values of compressor ratio on primary-zone-temperature, NOx, CO and UHC emission has been analyzed. It has been observed that the primary-zone-temperature and mass of NOX emission increases with increase in compressor pressure ratio whereas mass of CO and UHC emission decreases with increase in compressor pressure ratio.

This paper deals with the exergo-environmental analysis of gas turbine with possible application as aviation auxiliary-power-unit (APU). The present work reports a comparison of thermodynamic performance, NOx and CO emission for basic gas turbine cycle (BGT) and intercooled-recuperated gas turbine (IcRcGT) cycle based engines for possible use by the aviation industry as auxiliary power unit (APU). In addition to this environmental sustainability index of these two cycles is also presented. Various cycle operating parameters such as compressor-pressure-ratio (rp,c), combustor-primary-zone-temperature, equivalence-ratio, and residence time have been chosen for analysis of the cycles. Mathematical modeling of the cycles has been done and the same have been coded in MATLAB. Results show that IcRcGT cycle exhibits higher gas turbine power output and gas turbine efficiency in comparison to BGT cycle for the same rp,c and turbine inlet temperature (TIT).

In modern turboprop engines, reduction in emission and fuel consumption is the primary goals during the development of gas turbine aero engines. In this paper, a concept has been proposed for hybridizing the air blade cooled turboprop engines by integrating it with a fuel cell. The proposed study focuses on thermodynamic analysis of a turboprop engine integrated to a solid oxide fuel cell (SOFC) system. A solid oxide fuel cell is the perfect candidate for utilizing waste heat available at turboprop engine exhaust, through recuperation process. Integration of SOFC is ultimately leads to enhancement the overall performance of the turboprop-SOFC hybrid system. Power generated by the SOFC system can be utilized by the aircraft and in can complement the auxillary-power-unit (APU) and may even supplement it. On the basis of 1st and 2nd law of thermodynamic modeling analysis of a turboprop-SOFC system has been presented in this article.

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.

Automotive power packs have been the focus of research over a long period of time. Among various power packs when we consider internal combustion engines, there is an ample opportunity in developing systems that can make optimal utilization of all the energy streams related to the automotive engine. In this regard utilization of internal combustion engine exhaust waste heat and environmental pollution have been the focus of research in the recent past. About 35% of the automotive input fuel energy is converted to useful crankshaft work and about 30% energy is expelled with exhaust. This leaves about one-third (35%) of the total energy that must be transmitted from the enclosed cylinder through the cylinder walls and head to the surrounding. The exhausted energy from engine results in entropy elevation and solemn environmental pollution. So it is desired to utilize waste heat to the extent possible.

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).

Aircraft engines powering propulsion of the aircraft is the key component of the system. In aircraft industry it is desirable that an aircraft engines should supply high speeds (for military fighters) with low maintenance (for civil airplanes). In this regard an integration of gas turbine engines with traditional propeller has been introduced and termed as turboprop engine. In present work, a gas turbine with cooled blading has been proposed to be the turboprop engine which has been exergoeconomically analyzed to assess the performance and economics related to the proposed turboprop engine. Exergo-economic analysis is a tool which combines thermodynamic analysis and economic principles to provide information that is helpful to predict thermodynamic performance and total cost of the engine (thermal system). The methodology includes energy, exergy and cost balance equations for component-wise modelling of whole system.

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.

Global energy scenario requires thermal systems with higher efficiency and lower capital and operating cost. The paper deals with the thermoeconomic analysis of the gas turbine cycles with possible application as marine gas turbines. Thermoeconomic analysis of an energy conversion cycle is a combined study of thermodynamics and economics. Different configurations of gas turbine cycles have been analyzed using thermo-economic methodology keeping the gas turbine operating parameters (compressor pressure ratio, turbine inlet temperature, isentropic efficiencies of compressor & turbine etc fixed. Study has been carried out by considering appropriate objective function in a form of decision variables. This objective function combines both fuel cost and investment cost. Correlation functions having variables such as pressure ratio, isentropic efficiencies of compressor & turbine and turbine inlet temperature have been presented for obtaining capital cost for all equipments of the cycle.

In comparison to other thermal power cycles, gas turbine based energy conversion cycles exhibit superior thermodynamic performance as well as reduced emission. Gas turbine manufacturers and research & development (R&D) organizations are working on modification in basic gas turbine (BGT) cycle, which are intended to improve the basic gas turbine cycle thermodynamic performance and reduce emissions. The present work reports a comparison of thermodynamic performance, NOx and CO emission for basic and intercooled gas turbine (IcGT) cycles. Various cycle operating parameters such as compressor-pressure-ratio (rp,c), combustor-primary-zone-temperature, equivalence-ratio, and residence time of gas turbine based cycles has been examined. IcGT cycle exhibits higher gas turbine specific work and gas turbine efficiency in comparison to BGT cycle for the same rp,c and turbine rotor inlet temperature.

This paper focuses on the thermodynamic analysis of Solid Oxide fuel cell (SOFC). In the present work the SOFC has been modeled to work with internal reforming of fuel which takes place at high temperature and direct energy conversion from chemical energy to electrical energy takes place. The fuel-cell effluent is high temperature steam which can be used for co-generation purposes. Syn-gas has been used here as fuel which is essentially produced by steam reforming of methane in the internal reformer of the SOFC. A thermodynamic model of SOFC has been developed for planar cell configuration to evaluate various losses in the energy conversion process within the fuel cell. Cycle parameters like fuel utilization ratio and air-recirculation ratio has been varied to evaluate the thermodynamic performance of the fuel-cell. Output performance parameters like terminal voltage, cell-efficiency and power output have been evaluated for various values of current densities.

Energy generation and its use affect the surrounding environment. About sixty five percent of the energy comprises of global anthropogenic green house gas emissions which are renewable. Reduction of this emission must necessarily begin with action targeted shift of energy sources that are renewable. Out of the various sources of renewable energy biomass and specifically agro-biomass has a lot of potential as it can be utilized in the existing energy conversion systems with minor modification. Biomass can be utilized in energy conversion system by co-firing in a modern coal fired power plant with biomass content up to 10% by weight. The combustion efficiency of biomass feedstock can be about 10% lower than that for coal. Biomass can also be combusted in a dedicated power and combined-heat and power (CHP) plant that is typically smaller in size and of lower efficiency of up to 35%. In cogeneration mode the efficiency may go up to 90%.