Gas Turbine Power Output Research Articles

Power Augmentation of Gas Turbine Using Exhaust Flue Gas Operated Vapor Absorption Machine

Industrial gas turbines (GT) that operate at constant speed are constant-volume-flow combustion machines. As the specific volume of air is directly proportional to the temperature, an increase in air density results in a higher air mass flow rate at low air ambient temperatures. This results more mass of air is now passes through same volume gas turbine space. Consequently, the gas turbine power output increases proportionally with the increase in air mass flow rate. For geographic regions where warm and humid months are predominant throughout the year, significant power loss occurs during these months, and a higher rate of expensive fuel is fired at reduced power output. A gas turbine inlet air cooling technique is a useful option to enhance GT output. One of the innovative options for power augmentation of gas turbine is inlet air conditioning using a vapor absorption machine (VAM). Using VAM for GT intake air conditioning has the advantage over other systems in that it can be operated from waste heat. Many gas turbine machines, particularly natural gas pumping stations, are operated without heat recovery steam generator (HRSG) or heat recovery option. Valuable heat energy is escaped with exhaust flue gas in these systems. This paper demonstrates how GT exhaust waste heat can be utilized for its own power generation enhancement. In this study, a flue gas-based vapor absorption machine is selected for cooling the inlet air of a 26 MW gas turbine, which is used to drive the booster compressor of a natural gas pumping station. The capacity of the VAM for the required cooling effect has been calculated. The expected GT power enhancement from intake air gas conditioning has also been estimated in this paper.

Effects of compositional uncertainties in cracked NH3/biosyngas fuel blends on the combustion characteristics and performance of a combined-cycle gas turbine: A numerical thermokinetic study

Blending of partially cracked ammonia with biosyngas is an attractive strategy for improving NH3 combustion. In practice, products of biomass gasification and those of thermo-catalytic cracking of NH3 are subject to some compositional uncertainties. Despite their practical importance, so far, the effects of such uncertainties on combustion systems remained largely unexplored. Hence, this paper quantifies the effects of small compositional uncertainties of reactants upon combustion of partially cracked NH3/syngas/air mixtures. An uncertainty quantification method, based on polynomial chaos expansion and a data-driven model, is utilised to investigate the effects of uncertainty in fuel composition on the laminar flame speed (SL) and adiabatic flame temperature (Tad) at different inlet pressures (Pi). The analysis is then extended to the power output of a combined-cycle gas turbine fuelled by the reactants. It is found that 1.5% fuel compositional uncertainty can cause 12–21% of SL uncertainty depending on the inlet pressure. Furthermore, the effect of compositional uncertainty on Tad increases at higher ratios of H2 to NH3. Sensitivity analysis reveals that the uncertainty of CO contribution to SL uncertainty is higher than that of NH3, while the trend is reversed for the Tad uncertainty. In addition, the power output from the combined-cycle gas turbine system varies between 4 and 6% with 1.5% of fuel compositional uncertainty. This become more noticeable at elevated Pi [5–10 atm], particularly when the fuel mixture contains high H2 which is the main contributor to Tad variability.

Assessment and modelling of the waste heat availability from gas turbine based CHP systems for ORC systems

This paper presents the findings of modelling of waste heat availability from a Combined Heat and Power (CHP) system with a rated electrical output of 4.35 MW and steam production of 8,165 kg/hr at 16 barg. The model has been developed using HYSYS DynamicsTM. The amount of waste heat available from the CHP system is dependent on the ambient air, steam production, and gas turbine power output. A Pitot traverse measurement across the duct was undertaken to determine the actual amount of waste heat available from the CHP system. The measurements were conducted in accordance to BS EN 15259:2007 standards. The simulation results of waste heat availability have been compared to experimental data at various CHP power outputs. The HYSYS DynamicsTM model waste heat calculation was shown to be 5.3% lower than experimental waste heat measurements. An analysis of the waste heat availability by both modelling and experiment was done which shows that the CHP system waste heat available between 3.82 MW and 5.09 MW. Recovering this low grade heat from the CHP system using Clean CycleTM 125 ORC systems generates between 217 kW and 344 kW of electricity, respectively. Increases of 2.3% in electrical efficiency of the CHP system are predicted

Power generation gas turbine performance enhancement in hot ambient temperature conditions through axial compressor design optimization

The output power and efficiency of gas turbines are profoundly influenced by ambient temperatures, with higher temperatures resulting in a notable decline in power output. This issue becomes particularly critical during periods of heightened power demand in hot climates. There are two common ways to solve this problem: incorporating auxiliary systems, such as inlet air cooling, or undertaking a comprehensive redesign of the gas turbine core engine. However, these methods sometimes are costly and unfeasible, particularly in regions characterized by arid conditions or constrained budgets for engine modifications. An alternative strategy has been developed to optimize axial compressor performance in order to improve gas turbine power in high-temperature environments, through an innovative approach. This approach centers on the concept of “re-staggering” the stator blades as a retrofit upgrade for existing gas turbines, enabling an increase in compressor inlet mass flow rate while maintaining peak efficiency at 45 °C. An in-house optimization tool was developed, incorporating a genetic algorithm and artificial neural network, to ascertain the optimal configuration of the re-stagger angles. This optimization process was initially coupled with a mean-line solver and subsequently refined using a through-flow model to enhance the preliminary design. The refined compressor design was then subjected to a comprehensive 3D Computational Fluid Dynamics analysis. Additionally, “end-bend” and “elliptical leading edge” techniques were employed to sustain compressor efficiency and ensure stability across various design and off-design operating conditions. Following a thorough structural analysis, the newly designed compressors were manufactured and tested at two distinct sites in Iran (Yazd and Bampur). The measured data demonstrated the commendable performance and stability of the redesigned compressors, aligning closely with numerical predictions. Notably, the results showcased a substantial increase in gas turbine power output ranging from 7.0% to 8.0% at hot ambient conditions, all while preserving efficiency and stability. Encouragingly, the upgraded compressor also exhibited superior performance even at lower temperatures, such as 15 °C. Consequently, this uprating concept presents a practical and cost-effective solution for power plant operators seeking a significant boost in power output, especially during hot weather conditions or in arid regions prone to drought.

Natural gas-hydrogen hybrid combustion retrofit method and practice for F-class heavy-duty combustion engines

In order to reduce carbon emissions, enhance the operational flexibility of gas turbine power plants, and fill the gap in practical engineering transformation of natural gas-hydrogen blended combustion in heavy-duty gas turbines, a hydrogen blending retrofit was conducted on an F-class heavy-duty gas turbine combined heat and power unit. This served to examine the problems of combustion chamber tempering, combustion pulsation, and NOx emission increase caused by direct hydrogen-doped combustion in the combustion chamber. In this paper, the gas turbine body and hydrogen mixing system were reformed respectively. Retrofit schemes were proposed that were suitable for two operating conditions: 5%–15% and 15%–30% hydrogen blending. Experimental tests were conducted as a means of evaluating the performance of the retrofitted gas turbine and its compatibility with the boiler and steam turbine. The results of the retrofit showed there to be stable combustion, and there was no significant increase in average burner temperatures or occurrence of flashback. The gas turbine power output mostly remained unchanged and NOx emissions met the regulatory standards. The waste heat boiler flue gas temperature was controlled within the range of 84.9–88.2 °C, meaning that the safe operation of the steam turbine was not affected. The hydrogen blending rate was 0.2 Vol%/s, which indicates a smooth and precise control of the hydrogen blending process. It was estimated that the annual reduction in CO2 emissions would be 11,000 tons and 28,400 tons following respective hydrogen blending at 15% and 30%. A reliable retrofit scheme for hydrogen blending in gas turbines based on practical engineering transformation is presented in this study, which has significant reference value.

A review of gas turbine inlet cooling technologies

Gas turbine (GT) performance is primarily dependent on the inlet air temperature. The power output of gas turbine is dependent on the flow of mass through the gas turbine. This is why at hot weathers with less dense air, the power output drops, but at cold weather with high dense air, the power output rises. The inlet air cooling (IAC) technology is one of the major drivers that enhance the gas turbine performance, especially during the hot weathers. The performance of gas turbine is affected by various factors such as inlet air cooling, fuel type, fuel heating value, air temperature, turbine inlet temperature, humidity, site elevation, inlet and exhaust losses, air extraction, diluent injection, performance degradation, etc. The aim of this technical review is based on the comparative analysis of different gas turbine inlet air cooling (GTIAC) technologies and its applications based on the climate conditions. The power consumption due to inlet air cooling calls for major concern since it reduces the GT net power output. Different GTIAC has its unique benefits and challenges. The biggest gains from evaporative cooling are achieved during hot, low-humidity climates. Furthermore, the review paper showed that the efficiency of the evaporative cooler is majorly dependent on the moisture present in the air. The work also reveals that the feasibility of each GTIAC application is basically dependent on the location.

An evolutionary programming technique for evaluating the effect of ambient conditions on the power output of open cycle gas turbine plants - A case study of Afam GT13E2 gas turbine

In this research a novel Evolutionary Programming (EP) approach combined with a Continual Learning Neural Network (EP-CLNN) technique is proposed for the evaluation of Open Cycle Gas Turbines (OCGTs) net power output considering ambient temperature conditions. Studies were performed comparatively considering the proposed EP-CLNN approach, state-of-the-art linear regressors of several Polynomial (Poly) orders (Poly-1, Poly-2, Poly-3, and Poly-4) and three relatively small-to-big datasets. These approaches were applied to two open source datasets reported in the literature and a case study small dataset acquired from the Afam gas power station plant (GT132E2). The results showed that the reported Root-Mean Squared Error (RMSE) and mean net power estimates for the EP-CLNN are indeed promising considering the constraint of sequential continual learning prediction requirement, reduced variable (single input variable), simpler function set, and relatively small datasets. For the case of the big open source dataset (Dataset-1), the proposed EP-CLNN approach gave the best solution with least RMSE of 4.9926 MW over the linear regressors - Poly-1, Poly-2, Poly-3, and Poly-4 with RMSE estimates of 5.4609 MW, 5.2305 MW, 5.0986 MW, and 5.0980 MW respectively. For the case of the small dataset (Dataset-2), the estimated mean net powers were 32,974.0000 MW, 59140.0000 MW, and 96.2143 MW for Poly-1, Poly-2, and the EP techniques respectively; when compared to the base (reference) net mean power of 97.52 MW, the EP technique is the better one. Furthermore, for dataset 3, the EP technique gave an RMSE of 0.3381 MW while the combined solution of EP-CLNN gave a Mean Absolute Percentage Error (MAPE) consensus estimate of 0.1377 from a synthesized dataset of 20 evolved symbolic expressions. Thus, the EP-CLNN represents a promising approach to real-time gas turbine power output modeling with better accuracy and unique consensus expression capability.

System efficiency and power assessment of the all-aqueous copper thermally regenerative ammonia battery

Thermally regenerative ammonia batteries (TRABs) use low-temperature (T < 100 °C) heat to provide stationary energy and power with higher power densities and efficiency relative to other waste heat devices. TRABs are an active area of research in waste heat devices, but currently there is little consensus on what aspect of the system is limiting TRAB performance and what maximum efficiencies are possible. Experiments and numerical models were used here to examine the sensitivity of the battery and distillation column in a TRAB system to key operating variables, thereby establishing practical limits and identifying focus areas for improving performance. Battery power was eight times more sensitive to ohmic losses than kinetic and mass transfer losses, regardless of the operating temperature, and the peak power density was simulated to be 18.8 mW cm−2 at 75 °C. Theoretical energy efficiency limits were defined for a series of ammonia concentrations and operating pressures, ranging from 5 − 12%, which is 2–3 times higher than previous experimental estimations. Atmospheric pressure column operation used a larger amount of waste heat compared to sub-atmospheric pressure. It is estimated that the volume of the battery would take up 9.2 m3 for every 1% of the power output of a natural gas turbine, but with realistic improvements to cell conductivity, the size would reduce to 2.5 m3. The results presented in this work will help streamline future development by focusing on minimizing ohmic losses and provide specific data for full system evaluation of future TRABs.

System Performance and Pollutant Emissions of Micro Gas Turbine Combined Cycle in Variable Fuel Type Cases

This study focuses on an investigation of the operating performance and pollutant emission characteristics of a micro gas turbine combined cycle using biomass gas, replacing natural gas. The models of both recuperative cycle micro gas turbines with a waste heat utilization system and a micro gas-steam turbine combined cycle system are established. When the gas turbine works at 100 kW and the same types of fuel are burnt, the recuperative cycle system consumes less fuel than the gas-steam combined cycle system. The electric efficiency of the recuperative cycle system can reach more than 29%, which is higher than 24% of the gas-steam combined system. The combined cycle thermal efficiency of the recuperative system is as high as 66%, with 36% waste heat utilization efficiency. The electrical efficiency of the recuperative cycle system in the biomass gas case decreases, while that of the gas-steam combined cycle system undergoes little change. When the gas turbine power output increases from 50 kW to 100 kW, the electrical efficiency and combined cycle thermal efficiency increases, but the thermal efficiency of waste heat utilization of recuperative cycle decreases, the NOX and SO2 emissions gradually rise. Under the same working conditions, the NOX emissions of the recuperative cycle system are greater than that of the steam-gas combined cycle system.

PDA Laser Measurements of Droplet-Laden Flows in a Four-Stage Axial Compressor

Abstract Droplet-laden flows play a significant role in the development of turbomachinery. For example, fine water droplets are injected into the flow path of axial compressors to increase the power output of gas turbines by making use of evaporation cooling, often referred to as wet compression. Another example is the ingestion of rain droplets in aircraft engines. Therefore, thermodynamic and aerodynamic measurements of air and liquid are indispensable to better predict the following behavior of the droplets in the gas flow. This article presents a new PDA measurement setup for a droplet-laden four-stage axial compressor to analyze the droplet behavior in swirled flows. To reduce optical disturbances of the laser beam path, liquid films at the casing are suppressed by a boundary layer air injection. Supplementary investigations with this treatment show a negligible influence on the compressor behavior. To minimize refraction effects of the laser beams at the casing window, the laser device with the optical probes can be translated and rotated, thus having 4 degrees-of-freedom. Furthermore, the collected droplet data are compared with a mathematical description of velocity slip in superimposed air flows. For the first time, it can be shown experimentally that droplets smaller than 10 μm attain the velocity of air one stage after injection. For larger droplets, however, deviations from the air Mach number of up to 0.05 remain. In addition, detached liquid films behind the trailing edge of the stator blades with low velocities can be clearly detected.

Performance analysis of selective exhaust gas recirculation integrated with fogging cooling system for gas turbine power plants

Selective exhaust gas recirculation (S-EGR) is a proposed alternative for enhancing the CO2 capture units applied in power plants. Most previous studies focused on the correlation between S-EGR and CO2 capture unit efficiency. Nevertheless, the S-EGR system without pre-cooling considerably influences the gas turbine output power due to its relatively high temperature. Hence this study aims to investigate the influence of the integration of fogging cooling systems with S-EGR on gas turbine performance. This combination could reduce the adverse effects of the S-EGR system in power plants as well as increase the effectiveness of the fogging cooling system in hot, humid regions. A three-dimensional Euler–Lagrange CFD model is employed to simulate the mutual effect between S-EGR and fogging cooling systems under different operation conditions. The impact of output condition from combined fogging and S-EGR system (cooled CO2 enriched air) on the gas turbine performance is then investigated. Results illustrate that applying the fogging cooling approach after mixing the inlet air and S-EGR reduces the moisture content of the inlet air and augments the cooling capacity of the fogging system. When the CO2-enriched stream is pre-cooled to the same ambient temperature, the fogging system outlet temperature drops more, especially at high S-EGR ratios. Applying the S-EGR system could increase the inlet mixture density (CO2-enriched air) by about 12% at an S-EGR ratio of 35%, which is increased to 18% after incorporating the fogging cooling system. Regarding gas turbine performance, using CO2-enriched air without pre-cooling leads to a significant deterioration in performance, notably at high S-EGR ratios. On the other hand, the amalgamation of S-EGR with fogging cooling could boost gas turbine output power from 11.7 to 19.2%, with an efficiency gain of half a percentage point.

Theoretical and experimental study on effects of wet compression on centrifugal compressor performance

Through the internal cooling from evaporation of tiny water droplets during the compression process, wet compression can effectively augment the net power output of gas turbine under high ambient temperature condition. In this paper, effects of wet compression on compressor performance were theoretically and experimentally investigated on one of stages of a multistage centrifugal compressor and a new performance correction model for wet compression was proposed. This model is based on corrected similarity criterion and couples with equivalent gas properties of wet compression, droplet evaporation model and droplet dynamics loss. The results show that wet compression can increase pressure ratio and efficiency and reduce specific compression work at same pressure ratio. The effect enhances with the increase of water injection ratio and the decrease of droplet average diameter. The essence of influence on performance is the variation of equivalent isentropic exponent. For this stage, maximum pressure ratio and peak efficiency increase by 4.25% and 0.71% respectively with a water injection ratio of 2% and a droplet average diameter of 10 μm.

Thermodynamic analysis of gas turbine performance using the enthalpy–entropy approach

The enthalpy–entropy approach, which is a rigorous and accurate method, was used to model the actual cycle of a gas turbine (GT). The constructed GT C# programming language code was used to study the effects of ambient temperature ( T am ), relative humidity (RH), and ambient pressure ( P am ) on GT output parameters. The results of the GT modeling program showed that the maximum (minimum) difference in GT output power ( P GT ) was 1.12% (0.01%) at a T am of 39.7 °C (23.3 °C) compared with the actual output power of El Atf power station. As T am increased from 14 °C to 40 °C, the P GT decreased by 19.01% (18.38%) of nominal GT power (250 MW) at 15% (95%) RH while GT thermal efficiency ( η th ) decreased by 2.3058% (2.4431%) and the specific fuel consumption (SFC) increased by 7.12% (7.59%). The P GT decreased by 0.1497% and 0.7674% with an RH increase from 15% to 95%, respectively. The P GT decreased by 0.03675 and 0.16835 MW while η th decreased by 0.0047% and 0.0243% at T am values of 15 and 40 °C, respectively, when P am was decreased from 1.013 to 0.990 bar. Using the compressor assumptions of each stage increases the humid air pressure by the same value and the efficiency of each stage is the same and equal to the compressor overall efficiency is more logical and leads to accurate results. The compressor isentropic efficiency was not affected by the bleeding air percent according to the assumptions used.

Efficiency Enhancement of Gas Turbine Power Output by Cooling Inlet Air

Electrical power generation can be achieved through many means, one of which includes using a gas turbine. Gas turbine performance is highly dependent on ambient temperature; as temperature increases gas turbine power output is lessened. This can be a huge problem in warmer regions like Nigeria. Gas turbines use the surrounding air to generate electricity and this gives rise to a method or curbing the effect of high ambient temperatures. Once the volumetric rate is constant as is the case in a gas turbine system, air density and ambient temperature are inversely proportional; this allows mass flow rate to be inversely proportional to temperature. To fully take advantage of this, there are many methods that can be implemented to achieve this cooling effect. A few of these methods were investigated in this study to determine their strengths and susceptibilities. The performance characteristics were scrutinised for a range of operational values including ambient temperature, humidity and air density. The results showed that air cooling significantly improved the power output of the gas turbine. At standard temperature of 32oc, the base case was 37.87 MW while evaporative cooler, mechanical and absorption chillers were 37.70 MW, 40.39 MW and 41.07 MW respectively.

Efficiency Enhancement of Gas Turbine Power Output by Cooling Inlet Air

Efficiency Enhancement of Gas Turbine Power Output by Cooling Inlet Air

Simulation of innovative hybridizing M-cycle cooler and absorption-refrigeration for pre-cooling of gas turbine intake air: Including a case study for Siemens SGT-750 gas turbine

Higher compressor intake-air temperature not only significantly reduces the performance of the gas turbine (GT), but also increases the NOx emissions. Absorption (AB) refrigeration, which is powered by heat, is a promising option for cooling GT intake air. M-cycle technology is a unique water-based indirect evaporative cooler (IEC) providing sub wet-bulb temperature. In novel hybrid pre-cooler, the air is cooled down to near dew-point temperature by the M-cycle first and then further cooled by the AB. Both AB and M-cycle coolers consume very little electricity and the main required sources (heat for AB refrigeration and water for the M-cycle IEC) are provided by waste heat from GT and condensed water from AB meaning almost zero-energy pre-cooler for GT intake air. The dependency of the intake mass flow and GT power output on the intake air temperature is first identified and correlated using experimental data provided by Siemens company, and then the required physical/mathematical modelling is presented and developed using Engineering Equation Solver. Finally, the GT performance is comprehensively discussed for a wide range of climate conditions when the AB and M-cycle work solely or jointly as a GT intake air pre-cooler. The hybrid pre-cooler was found to be a cost-effective way to boost the GT power output by 29%, however, this enhancement for GT using AB refrigeration and M-cycle IEC was around 17% and 15% in average respectively.

A dynamic interactive optimization model of CCHP system involving demand-side and supply-side impacts of climate change. Part I: Methodology development

Combined cooling, heating and power (CCHP) system, as a superior energy-provision form of public building, is capable of achieving flexible and stable energy provision with high energy-utilization efficiency and low pollutant emission. However, some difficulties exist in operating such a system, due to its intrinsic multi-period, multi-factor and multi-layer features. In addition, the fluctuation in weather elements under climate change exacerbates the inaccuracy of energy demand prediction and facilities’ power output calculation, leading to imbalanced energy supply and demand. To tackle this issue, a dynamic interactive model combining user-demand prediction, energy-provision calculation and operational collaborative optimization was developed. It attempts to combine the regional climate simulation (PRECIS), demand prediction (TRNSYS), equipment output calculation (mechanism modeling) and collaborative optimization (LINGO) into a general framework. The specific operation processes include: (i) utilize PRECIS model to identify the variations in temperature and radiation under climate change; (ii) exploit TRNSYS software to predict the users’ demand of targeted hospital in the future; (iii) establish a mechanism simulation model for gas turbine and estimate power output under extreme meteorological condition; (iv) incorporate the results generated by processes (ii) and (iii) into formulated operation optimization model of CCHP system; (v) generate optimal energy provision scheme adapted to climate change. This dynamic interactive model comprehensively considers the interactions at all aspects involved into operation management of CCHP system and improves the economy and adaptability of operation pattern. This study mainly addressed the problem background and model formulation. A detailed case study will be discussed in another follow-up work.

High ambient temperature effects on the performance of a gas turbine-based cogeneration system with supplementary fire in a tropical climate

High ambient temperature negatively affects gas turbine performance, especially in a tropical climate. Cogeneration improves fuel utilization by taking advantage of the energy discharged as waste heat in the exhaust gases. This case study assesses the effects of high ambient temperature on the performance of a natural gas-based cogeneration plant in Barranquilla, Colombia, a location with a hot and humid tropical climate throughout the year with an annual average temperature of 27.4 °C. The cogeneration plant encompasses gas and vapor turbine generation, supplementary fire, waste heat recovery, and process heat exchange. Validated ASPENHYSYS® simulation allows comparing gas-turbine-alone indicators with those at ISO conditions, i.e., 15 °C and 101.3 kPa. Ambient temperature reduces gas turbine power output by up to 22% and decreases thermal efficiency by around 0.06% for every °C rise above ISO conditions. Cogeneration with and without supplementary fire increases power output by 17% and 5% compared to gas-turbine-alone operation. The energy utilization factor increases by 27–37% without supplementary fire and above 37% with supplementary fire. Results give insight into the challenges of cogeneration plants in a tropical climate. Further studies should include the effects of high humidity on power plant performance and the potential benefits of cooling inlet air.

A model for booster station matching of gas turbine and gas compressor power under different ambient conditions

Transporting natural gas across different locations require compressor stations to provide the pressure needed to keep the gas moving. This paper presents a model for matching the gas turbine and gas compressor power required under different environmental conditions to support the continuous gas transmission across other locations. The trans-Saharan gas pipeline (TSGP) project proposed to transport gas from Nigeria to Algeria has been used as a case study in this paper. The TSGP project is a Nigerian Government initiative to rejig its gas development and transportation infrastructure to meet its internal and external market demand. The numerical method used in this paper integrates the effect of the ambient temperature in the power matching of the gas turbine and gas compressors. There are 18 compressor stations across the TSGP network, and compressor station 2 is used as the reference point. The daily temperature fluctuation is segmented into hours of the day, emphasising considerable ambient temperature variation at 3:00 h, 9:00 h, 15:00 h. One benefit of the model against others in the open literature is accounting for changes in the ambient temperature along the pipeline network and gas compression stations. Accounting for changes in ambient temperature provides accuracy to near real-life operational experience for gas distribution via pipelines. The model also accounts for variations in turbine entry temperature (TET) to compensate for changes in the ambient conditions to meet the power requirements of the gas turbine and the gas compressor. The results show that for every 1% increase in ambient temperature, a 3.5% increase in power is required to drive the gas compressor and a 1% decrease in gas turbine output power. The effect of the 1% increase in ambient would require a 3.5% increase in TET to meet both the gas turbine and gas compressor requirement.

Proof of Concept for a Novel Interstage Injection Design in Axial Compressors

Abstract A common technique to increase the thermal efficiency and the power output of gas turbines is to inject water upstream of the compressor section. Through the evaporation of the water throughout the compressor, an isothermal process is approached. A recently developed technology for this enhanced process is interstage injection in which water is injected directly between the stages. One advantage of this over wet compression is the avoidance of icing, since the local temperatures at the injection positions are already above melting point. Moreover, stage characteristics and load distribution can be rearranged within the compressor by individually adjusting the injection amount in different stages. However, there is little practical understanding of this process, and suitable injection methods have still to be found. This paper therefore demonstrates the implementation of a novel technology of interstage injection in an axial compressor test rig whereby twin jet nozzles are integrated directly into the trailing edge of the first stator row to deliver a homogenous spray over the entire radial span. Due to the resultant blade complexity, blades are manufactured by selective laser melting (SLM) and subsequently installed in an enhanced four-stage axial compressor. The installed control and measurement principles of the test rig are presented and results demonstrate the functionality of the innovative design.