Gas Turbine Cycle Research Articles

Thermodynamic Investigation of ORC Integration in Solar Assisted Gas Turbine Cycle

Worldwide, governments of many countries are worried about global warming due to pollution created by burning fossil fuels to meet energy demand. Nonetheless, they are bothered about the finite availability of fossil fuels on the planet. As a result, it is desirable to reduce dependency on nonrenewable fuels and replace them with renewable energy to meet energy demand. Solar energy is the most cost-effective fossil-fuel replacement. However, the investigators are apprehensive about the resourceful use of solar energy. This led the researcher’s attention to the organic Rankine cycle (ORC), which might be integrated with the standard energy production cycle to make the most of the available energy. The present study performs the thermodynamic investigation of the integrated ORC in the solar-assisted gas turbine cycle. The acquired results reveal that integrated ORC in solar-assisted gas turbine cycle yields an increment in efficiency from 34.57 % to 69.89 % for the solar-assisted gas turbine pressure ratio of 16 bar, the ambient temperature of 300 K with ORC’s pressure ratio of 4 bar, and ORC turbine inlet temperature of 443 K.

Ammonia-hydrogen-air gas turbine cycle and control analyses

Blending ammonia with hydrogen has the potential of replacing conventional hydrocarbon fuels to reduce carbon emissions. However, the uncertainties of determining safe, stable, and efficient operating conditions remain a great challenge. Furthermore, although control technologies have been in the scope of interest for gas turbine manufacturers, those are not yet specialized for NH 3 –H 2 /air gas turbines. Therefore, this paper identifies the cycle performance of an NH 3 –H 2 /air gas turbine in comparison to a CH 4 /air gas turbine, thus highlighting the operating conditions in which the NH 3 –H 2 /air gas turbines show higher performance compared to the CH 4 /air gas turbines. The results have been obtained by developing a LabVIEW code which has also been utilized to serve as a control code for the NH 3 –H 2 /air and CH 4 /air gas turbines. The system identification stage of calibrating the controller has been achieved for both gas turbines by determining the system's sensitivities, thus providing an accurate calibration of the controlling parameters. • Higher NH3–H2/air gas turbines performance compared to CH4/air gas turbines. • System identification, cycle, and sensitivity analyses of NH3–H2/air gas turbines. • Developing and calibrating an NH3–H2/air gas turbines controller.

Thermodynamic performance study of a new diesel-fueled CLHG/SOFC/STIG cogeneration system with CO2 recovery

A new type of diesel-fueled cogeneration system is proposed in this study. The system mainly includes solid oxide fuel cell, chemical looping hydrogen generation and steam injection gas turbine cycle. The system can effectively avoid the carbon deposition of solid oxide fuel cell, recovering CO2 without separation energy consumption. Additionally, it adopts the way of centralized supply of steam and air, thus reducing the complexity and loss of the system. On this basis, the system is comprehensively evaluated by sensitivity analysis, exergy analysis, energy utilization diagram analysis and exergoeconomic analysis. It is found that the total power efficiency, exergy efficiency and fuel energy saving ratio of the new system can reach 64%, 60% and 60% respectively. Meanwhile, the power production cost of the new system is 51.25 $/GJ, and the optimization suggestion of the system is given according to the result of exergoconomic analysis. The proposed system provides a theoretical basis and new idea for the design and construction of diesel-fueled energy supply system.

Characteristics Analysis of Combined Cycle Coupled With High Temperature Gas-Cooled Reactor Based on Progressive Optimization

Owing to the current serious environmental and climate problems, the energy industry must focus on the problem of energy utilization rates. High-temperature gas-cooled reactors (HTGRs) are fourth-generation reactors, characterized by high outlet temperatures. The combined cycle is composed of the gas turbine and steam turbine cycles, and it can realize the cascade utilization of high-quality energy. It is a highly competitive power conversion scheme for HTGRs. In this study, the matching characteristics of the combined cycle coupled with HTGRs are revealed through the progressive optimization method. In the combined cycle coupled with HTGRs, the topping and bottoming cycle are both closed cycles, therefore, the optimization for cycle efficiency is to match the topping and bottoming cycles. For a combined cycle with subcritical steam parameters, there are two extreme values of the combined cycle efficiency that have different power ratios. The characteristics revealed in this study are unique to closed combined cycle coupled with HTGRs.

Optimal operation of a multi-generation district energy hub based on electrical, heating, and cooling demands and hydrogen production

In this study, a new configuration of a multi-generation energy system is proposed based on waste heat recovery from a regenerative gas turbine cycle (as the driver cycle) for running a district heating heat exchanger, a Rankine cycle, an ejector refrigeration cycle, and a proton exchange membrane electrolyzer cycle. In the first phase of the study, a thorough parametric model of the system is developed in EES software based on the eco-exergy and enviro-exergy analyses. The second phase is focused on the optimal operation of the system utilizing a robust multi-criteria optimization in Matlab software. Results of the parametric study showed that: (i) the share of fuel, capital, and environmental penalty costs rates in the system's total cost rate are respectively 46.95%, 29.38%, and 23.67%, at the optimal conditions. (ii) although the design variables of the bottoming cycles are not effective on the amount of pollutants, they have a significant effect on the enviro-exergy assessment criterion. The optimal system productions are included 21.42 MW of power, 26.81 MW of heat, 8.89 MW of cold, and 11.96 kg/h of hydrogen. The energy and exergy efficiencies are found to be 89.75% 35.21%, respectively. In such conditions, the payback period is approximately 5 years, demonstrating the economic feasibility of the proposal. Recovering the waste heat of conventional cycles to develop an energy production hub with minimal energy loss is one of the most important challenges in the energy matrix and relying on the results of the present study, it can be concluded that the proposed system has done this task well.

Impact of fuel type on the performance of a solid oxide fuel cell integrated with a gas turbine

This study investigates the performance of a flame-assisted fuel cell integrated with a gas turbine operating with six fuels (CH4, C3H8, JP-4, JP-5, JP-10, and H2). A thermodynamic model is developed for the fuel-rich combustion, fuel-lean combustion and each step of the gas turbine including the compressor, turbine and recuperator in order to analyze the overall hybrid gas turbine cycle. As the fuel/air equivalence ratio increases, the hybrid system efficiency increases initially then decreases despite increasing hydrogen concentration in the exhaust. The peak efficiency occurs around an equivalence ratio of 2 for all fuels. The optimal performance of the hybrid system utilizes H2 as the fuel. The peak electrical efficiency of the hybrid setup is 64.7% with H2 fuel, 60.3% with CH4 fuel, 60.9% with C3H8 fuel, 61.7% with JP-4 fuel, 61.0% with JP-5 fuel and 61.2% with JP-10 fuel, representing a significant increase over the standard gas turbine cycle. With H2 fuel, the overall integrated system is predicted to be 24.5% more efficient than the standard gas turbine system. These results show promise for a fuel flexible hybrid gas turbine which could benefit the growing aircraft industry as the desire for a more electric airplane increases.

Extremum analysis based on exergy and economic principle for ejector-absorption cycles combined with regenerative organic-Rankine and gas-turbine cycles

A combined cooling and power cycle is proposed for the establishment of a new system for the waste heat recovery process. The new system consists of a gas turbine coupling a heat recovery steam generator with the regenerative organic Rankine cycle and an ejector-absorption refrigeration cycle. The system analysis is carried out comprehensively through thermodynamic and economic viewpoints. The principal goal of the present study is to address the thermodynamic and economic viability of the proposed system and identify some possible improvements. In addition, the cost-effectiveness of the proposed cycle and the implemented methodologies has been examined. The key results show that the combustion chamber is the major source of irreversibility and it is responsible for 45.81% % of the total exergy destruction. Furthermore, the exergoeconomic factor of a combustion chamber is 0.0051 indicating that the cost of exergy destruction is more than that of the investment cost. In order to assess the effect of major design parameters, a parametric study is conducted. A thermodynamic study using R141b, R601a, and R123 is made and compared at various conditions. It is found that R141b is more suitable for improving the power output from the regenerative organic Rankine cycle. Finally, a multi-objective optimization is performed to determine the overall exergy efficiency and the total product cost as objective functions. At optimum conditions, the overall exergy efficiency and the total product cost are obtained as 0.4418 and 54.84 $/GJ, respectively. The operating temperature range in the generator of the ejector absorption system changes with respect to the conventional system values and the range of the optimum performance condition obtained is to be more practicable to avoid the crystallization state.

К применению низкотемпературных рабочих тел и сверхкритических флюидов для снижения углеродного следа при производстве карбамида и в пиролизе углеводородов

Low-temperature working fluids and supercritical fluids for use in compressor equipment drives in a number of areas are considered: production of urea, pyrolysis of hydrocarbons in the production of olefins. In the existing technologies, the energy consumption in the form of high-pressure steam for compression is very high. The use of closed gas turbine cycles will significantly reduce the consumption of such high-temperature energy while simultaneouslyusing the heat of intermediate technological flows, saturated low-pressure steam and additional low-potential heat discharged under existing conditions to cooling towers or leaving with flue gases.

Research on an integrated power and freshwater generation system from natural gas energy and geothermal sources

Waste heat recovery can recognize as a promising option for responding to the thermodynamic effectiveness and environmental issues through well-organized designs of multigeneration systems. Hence, this paper introduces a novel hybridization of a flash-binary geothermal cycle, a gas turbine cycle, an organic flash cycle, and a multi-effect desalination subsystem to reach efficient cogeneration of electricity and freshwater regarding the smart use of waste heat. The capability of the proposed system is analyzed based on energy, exergy, exergoeconomic, and economic perspectives, where the net present value and payback were considered as the system's evaluation criteria from the economic viewpoint. Accordingly, the multi-objective grey wolf optimization algorithm in conjunction with the LINMAP decision-making approach has been utilized to optimize the system and specify the optimal conditions in three optimization scenarios. According to the base operation conditions, the system has an exergy efficiency of 37.45% with a power generation capacity of 19.02 MW, a total freshwater rate of 38.69 kg/s, and a total profit and payback period of 60.07 $M and 3.75 years. Besides, the triple-objective optimization illustrated the exergy efficiency, profitability, and payback period of 38.41%, 62.71 M$, and 3.26 years, respectively.

Investigation of wet ammonia combustion characteristics using LES with finite-rate chemistry

The interest in climate action and building sustainable energy system, has highlighted electricity derived fuels (eFuels) and has promoted studies considering ammonia as a eFuel for sustainable transportation and as a mean of energy storage. Ammonia combustion, however, poses several challenges due to the low reactivity and potential high NOx emissions. A promising solution is to add hydrogen and steam into the fuel/air mixture. Steam contributes to the enhancement of specific power output and efficiency in humidified gas turbine cycle, and hydrogen promotes reactivity of the eFuel and can be obtained by ammonia decomposition on-site. In the present study, wet combustion of ammonia/hydrogen blends is systematic studied using one-dimensional flame analysis and Large eddy simulation (LES) to understand the flame stabilisation and NOx formation mechanisms. When hydrogen content is low (H2%<30%vol) and Tad = 1750 K, flame speed is nearly independent while flame thickness is significantly dependent on the equivalence ratio Φ due to the steam dilution. At high hydrogen content, the reverse applies. The impact of the H2% on the emission is non-monotonic, peaking between 60%∼70% at various Φ. Rich and stoichiometric combustion benefits NO reduction at a balance of H2% and steam dilution. High fidelity LES demonstrates that the steam diluted hydrogen/ammonia blends can be stably burnt in a swirl burner in a MILD regime. The wet combustion distributes the flame at low H2% and reduces local NO emission. In rich conditions, low NO emission attributes to the activation of NO reburning progress. Compared to dry condition, low steam addition (Ω=0.1) in the reactant lifts the flame and enlarges the opening angle of the swirling flow. When flame speed is low, POD analysis shows two PVC related structures - a single and a double helix, which dominate the flow and flame dynamics. While when flame speed is high, quick combustion process damps the precessing motion.

Combined effect of variable parameters on the performance of gas turbine cycles

The gas turbine cycle is the key solution for the power generation system from the last decade. several types of research are going to enhance the overall system efficiency of the gas turbine cycle. In the present study, six sets have been investigated parametrically for energy and exergy. Thermodynamic assessments have been effectively achieved for the compressor pressure ratio from 4 to 14, turbine inlet temperature (TIT) from 1000K to 1500K, and ambient temperature 250C to 450C. Results show that for every 100 rises in ambient temperature the maximum decrease in peak output and peak thermal efficiency is 6.2% and 5% respectively at 1000K and 3.6% and 1.9% respectively at 1500K. The exergy loss by exhaust gases of set 4 and set 5 increased by 107% whereas set 6 is decreased by 85.5% as compared to set 1 under the conditions when the exergy loss by exhaust gases of set 1 is minimum at TIT 1000K. The total exergy destruction of set 3, set 4, set 5, and set 6 is increased by 102%, 32.6%, 133.3%, and 102% respectively as compared to set 1 under the conditions when the total exergy destruction of set1 is minimum at TIT 1000K. Regenerative Gas Turbine cycle is the best in terms of the ratio of net output to exergy destruction of the plant as well as initial, operational, and maintenance costs.

Thermodynamic Study of a Cooled Micro Gas Turbine for a Range Extended Electric Vehicle

Carbon dioxide released by the transportation sector has a significant impact on the environment. Nowadays, the research efforts are thoroughly investing in the capability of series hybrid electric vehicles in reducing CO2 and NOX emissions. Many regulations are encouraging automakers to substitute internal combustion engines with electric vehicles. Although the latter are zero-emissions energy sources, they are expensive and have a limited autonomy range. Therefore, recent studies are interested in gas turbines (GTs) in series hybrid electric vehicles (SHEV). A gas turbine (GT) coupled to an alternator is considered as an auxiliary power unit capable of charging the battery of the electric vehicle once depleted. The microturbine is generally composed of a centrifugal compressor and a radial turbine mounted on the same shaft with a recuperator and air bearings. Based on previous researches and thermodynamic analysis, the most suitable gas turbine cycle with regard to the efficiency and the net specific work is composed of two compression stages with an intercooler, a regenerator, and two expansion stages with a reheater. It can be deduced that by increasing the turbine inlet temperature, the system efficiency increases. However, the inlet temperature is limited by turbine materials constraints and specifications. The present paper focuses on developing a more efficient GT cycle by reaching higher inlet temperatures by cooling the turbine blade. It consists of using compressed gas from the compressor and introduce them into the turbine blades. This technology takes into consideration the influence of the extracted mass of compressed air, the effectiveness of the coolant, and the turbine blade temperature on thermal efficiency. An increase of the cycle efficiency of 4.78 points is obtained for a turbine inlet temperature of 1,450 °C.

Ideal scheme selection of an integrated conventional and renewable energy system combining multi-objective optimization and matching performance analysis

Integrating advanced renewable energy into traditional energy systems could be quite beneficial for reducing emissions of greenhouse gases. A solar and geothermal energy assisted integrated energy system (IES) is proposed employing a gas turbine, absorption and ground heat pump cycles, and electric and thermal storage units. The multi-objective optimization approach considering the energy, environmental and economic performance is employed to optimize the system using genetic algorithm (NSGA- II) in MATLAB software. The operating strategies of the IES are considered by introducing four operational modes based on following the thermal or electric loads modes (FTL/FEL) and prioritizing the use of non-grid electricity. The coupled weighted thermal and electric matching performance of the hybrid energy system is chosen as the decision-making parameter for finding the ideal system solution from the Pareto frontiers. The results demonstrate that the FEL mode obtains a better coupled matching performance than the FTL mode, but the goodness of the matching is also influenced by the weighting method employed. The best performance improvements obtained over a traditional system is 36.4% for the economic benefits, and the highest energy and environmental benefits found are 47.9% and 60.7%, respectively. The best coupled matching performance found is 90.6% with a thermal and electric matching of 68.7% and 89.1%, which corresponds to an ideal performance with benefits of 35.3% for energy, 51.2% for emissions, 36.3% for costs, respectively. The carbon tax has a major impact on the economic performance of the solutions and could improve the cost saving ratio up to 38.3% when using a higher CO2 tax.

Chemically Recuperated Gas Turbines for Offshore Platform: Energy and Environmental Performance

Currently, offshore areas have become the hotspot of global gas and oil production. They have significant reserves and production potential. Offshore platforms are energy-intensive facilities. Most of them are equipped with gas turbine engines. Many technologies are used to improve their thermal efficiency. Thermochemical recuperation is investigated in this paper. Much previous research has been restricted to analyzing of the thermodynamic potential of the chemically recuperated gas turbine cycle. However, little work has discussed the operation issues of this cycle. The analysis of actual fuel gases for the steam reforming process taking into account the actual load of gas turbines, the impact of steam reforming on the Wobbe index, and the impact of a steam-fuel reforming process on the carbon dioxide emissions is the novelty of this study. The obtained simulation results showed that gas turbine engine efficiency improved by 8.1 to 9.35% at 100% load, and carbon dioxide emissions decreased by 10% compared to a conventional cycle. A decrease in load leads to a deterioration in the energy and environmental efficiency of chemically recuperated gas turbines.

Thermodynamic evaluation of a novel solar-aided biogas polygeneration system integrated with steam network etwork

The limited resources of fossil fuel and environmental concerns necessitate utilizing renewable resources which are less environmentally harmful. A new cogeneration system integrated with CCS and hydrogen production units is developed and analyzed in detail by introducing biogas and solar energy. The proposed system is presented to provide the heating demand of a utility system by designing a proper heat recovery. Concentrated solar thermal (CST) tower, biogas reformer, gas turbine cycle (GTC), organic Rankine cycle (ORC), pressure swing adsorption (PSA), carbon capture and storage (CCS) as the topping system and steam network (SN) are the components of this system. The devised system is evaluated from the energy point of view. A comprehensive parametric analysis is conducted for assessing the impact of the main parameters. The results demonstrate that integrating the SN and topping system increases the energy efficiency from 51.72% to 60.55%. Consequently, the net power generated by the system is increased from 32.147 MW to 57.634 MW.

Blade Roughness Effects on Compressor and Engine Performance—A CFD and Thermodynamic Study

Degradation of compressors is a common concern for operators of gas turbine engines (GTEs). Surface roughness, due to erosion or fouling, is considered one of the major factors of the degradation phenomenon in compressors that can negatively affect the designed pressure rise, efficiency, and, therefore, the engine aero/thermodynamic performance. The understanding of the aerodynamic implications of varying the blade surface roughness plays a significant role in establishing the magnitude of performance degradation. The present work investigates the implications due to the degradation of the compressor caused by the operation in eroding environments on the gas turbine cycle performance linking, thereby, the compressor aerodynamics with a thermodynamic cycle. At the core of the present study is the numerical assessment of the effect of surface roughness on compressor performance employing the Computational Fluid Dynamics (CFD) tools. The research engine test case employed in the study comprised a fan, bypass, and two stages of the low pressure compressor (booster). Three operating conditions on the 100% speed-line, including the design point, were investigated. Five roughness cases, in addition to the smooth case, with equivalent sand-grain roughness (ks) of 15, 30, 45, 60, and 150 µm were simulated. Turbomatch the Cranfield in-house gas turbine performance simulation software, was employed to model the degraded engine performance. The study showed that the increase in the uniform roughness is associated with sizable drops in efficiency, booster pressure ratio (PR), non-dimensional mass flow (NDMF), and overall engine pressure ratio (EPR) together with rises in turbine entry temperature (TET) and specific fuel consumption (SFC). The performance degradation evaluation employed variables such as isentropic efficiency (ηis), low pressure compressor (LPC) PR, NDMF, TET, SFC, andEPR. The variation in these quantities showed, for the maximum blade surface degradation case, drops of 7.68%, 2.62% and 3.53%, rises of 1.14% and 0.69%, and a drop of 0.86%, respectively.

Techno-economic and techno-environmental assessment and multi-objective optimization of a new CCHP system based on waste heat recovery from regenerative Brayton cycle

This investigation aims to present thermo-environmental and thermo-economic parametric studies for a new hybrid tri-generation energy system. In system, a regenerative gas turbine cycle (RGTC) is the runner system, while Kalina cycle (KC) and ejector refrigeration cycle (ERC) are considered as companion elements. The parametric study is done through validated computational program developed in EES software. Two new functions of levelized total annual emissions and costs (LTAE and LTAC), with two conventional indices of energetic and exergetic efficiencies (ηen and ηex) are defined for system evaluation. Thermodynamics modeling revealed that almost 75 % of total exergy destruction is related to the RGTC. The outputs of parametric study prove that pressure ratio of compressor and pinch-point temperature of heat exchanger 2 are the most and least effective parameters, respectively. Also, for the bottoming cycles, changes in KC design parameters resulted in creation of peak points in all the evaluation criteria; but changes in the ERC design parameters resulted in uniform (ascending or descending) behavior in the evaluation criteria. The NSGA-II optimization procedure (using MATLAB software) results in ηen,opt = 77.17 %, ηex,opt = 38.94 %, LTAEopt = 9.36 kg/kW.yr, and LTACopt = 106.04 €/kW.yr. The payback period and net present value of the tri-generation system are found as 3.74 yr and 1184525.43 €.

Effect of Expansion Direction/Area Ratio on Loss Characteristics and Flow Rectification of Curve Diffuser

Curve diffuser is frequently used in applications such as HVAC, wind- tunnel, gas turbine cycle, aircraft engine etc. as an adapter to join the conduits of different cross-sectional areas or an ejector to decelerate the flow and raise the static pressure before discharging to the atmosphere. The performance of the curve diffuser is greatly affected by the abrupt expansion and inflection introduced, particularly when a sharp 90o curve diffuser is configured with a high area ratio (AR). Therefore, the paper aims to numerically investigate the effect of the expansion direction of AR=1.2 to 4.0 curve diffuser on loss characteristic and flow rectification. 90o curve diffuser operated at inflow Reynolds Number, Rein=5.934 × 104 to 1.783 × 105 was considered. Results show that pressure recovery improves when the area ratio increases from 1.2 to 2.16 for both 2D expansion (z- direction) and 3D expansion (x- and z- direction). On the other hand, the increase of inflow Reynolds number causes the flow uniformity to drop regardless of the expansion directions. 3D expansion (x- and z- direction) curve diffuser with AR=2.16, operated at Rein=8.163 × 104, is opted as the most optimum, producing the best pressure recovery up to 0.380. Meanwhile, 2D expansion (z-direction) curve diffuser of AR=2.16, , operated at Rein= 5.934 × 104, is chosen to provide the best flow uniformity of 2.330 m/s. 2D expansion (x- direction) should be as best avoided as it provides the worst overall performance of 90o curve diffuser.

Optimization research on the off-design characteristics of partial heating supercritical carbon dioxide power cycle in the landfill gas exhaust heat utilization system

• Off-design characteristics of partial heating supercritical CO 2 cycle are studied. • A novel calculation flow chart for the system off-design performance is proposed. • Separation control and inventory control are adopted for the thermal system. • A best control scheme relied on the net power maximization can be determined. Landfill gas waste heat power generation is an effective way to promote the efficiency and economics of power plants. However, the operating performance of the power generation system needs to be improved further. In this paper, a systematic optimization research on the off-design characteristics of the partial heating supercritical carbon dioxide power system for exhaust heat utilization from gas turbine cycle are conducted. Optimal operating conditions in thermodynamics and economics obtained by genetic algorithm are determined as design conditions. Gradient descent method is used to obtain the best operating point under a certain off-design working condition. With the goal of maximizing net power output, separation control and inventory control are applied to the system. The results exhibit that the best thermoeconomic performance can be gained when the pressure ratio is 2.28 with separation ratio of 0.35 at design stage. In the off-design stage, the maximum net power shows an approximately linear growth trend from 1581 kW to 2924 kW with increasing heat source temperature and mass flow rate under the inventory control, while growth rate of net power output gradually decreases under the separation control. Finally, the best control scheme mixed with inventory control and separation control is proposed and determined quantitatively.

Research on the effectiveness of the key components in the HAT cycle

Humid Air Turbine (HAT) cycle is considered to be one of the most advanced gas turbine cycles due to its high efficiency, flexible operation, low NOX emissions, and low investment cost. The heat recovery determines the temperature field distribution of the humidification process, which is critical to the performance of the HAT cycle. However, so far, the effect of heat recovery of heat exchangers on cycle performance is still a research gap. Filling up the research gap is of great significance to the full utilization of the thermodynamic potential of the HAT cycle. This paper built a humid air turbine cycle with additional heat exchangers (aftercooler, regenerator, economizer) based on a humid air turbine test rig. A comprehensive thermodynamic analysis of the effectiveness of the heat exchanger components had been carried out. To conclude, the water–air ratio, aftercooler effectiveness and regenerator effectiveness can effectively affect the humidification performance and efficiency. The above analysis provided a theoretical reference for the actual transformation and performance enhancement of the test rig. In addition, research on the influence of the water–air ratio on the HAT cycle at different power outputs showed that the optimal water–air ratio gradually decreases with the increase of power output. The effect of the pressure ratio on the HAT cycle was clarified by comparison with a simple regenerative cycle. Finally, exergy analysis of the HAT cycle was carried out based on different optimization strategies. For the humid air turbine of 4 MW-class, increasing recuperator effectiveness is one of the effective techniques to enhance exergy recovery as well as efficiency, and improving the proportion of exergy utilized for water evaporation can augment specific work output. The maximum efficiency of 48.5% was obtained where its corresponding exergy efficiency reaches 44.4%. The maximum specific work output of 560.6 kJ/kg was achieved with an exergy efficiency of 38.0%.