A new analysis of recuperative gas turbine cycles

1998 ◽  
Vol 212 (4) ◽  
pp. 289-296 ◽  
Author(s):  
R Cai
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Optimum Pressure ◽  
Calculation Results ◽  
New Criterion ◽  
Gas Turbine Cycle ◽  
Cycle Efficiency ◽  
Analytical Expressions ◽  
Typical Calculation

It is shown that the classical recuperator effectiveness is not an appropriate evaluation criterion for the gas turbine recuperator or a suitable independent thermodynamic parameter of the recuperative gas turbine cycle. Another parameter—the average heat transfer temperature difference in the recuperator—is recommended as the new criterion instead of the recuperator effectiveness. Therefore, the original classical analysis results of the recuperative gas turbine cycle are also inappropriate and it is necessary to give a new analysis. In this paper, the analytical expressions of the simple recuperative cycle efficiency and the optimum pressure ratio based on the new criterion are derived from general simplified assumptions. Some typical calculation results are also presented. With this new criterion, the optimum pressure ratio values for efficiency of a simple recuperative gas turbine cycle do not vary very much with the temperature ratio and are approximately equal to 3, much lower than the figures generally recognized before. A similar analysis for the recuperative gas turbine cycle with intercooler and reheater and an analysis ensuring approximately constant recuperator heat transfer area per unit power output are given also.

Evaluation of the Compression-Intercooled Reheat-Gas-Turbine-Combined Cycle

1984 ◽  
Author(s):  
Ivan G. Rice
Keyword(s):  
Gas Turbine ◽  
Thermodynamic Analysis ◽  
Pressure Range ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Time Increase ◽  
Efficiency Loss ◽  
Gas Turbine Cycle ◽  
Cycle Efficiency ◽  
Turbine Output

Interest in the reheat-gas turbine (RHGT) as a way to improve combined-cycle efficiency is gaining momentum. Compression intercooling makes it possible to readily increase the reheat-gas-turbine cycle-pressure ratio and at the same time increase gas-turbine output; but at the expense of some combined-cycle efficiency and mechanical complexity. This paper presents a thermodynamic analysis of the intercooled cycle and pinpoints the proper intercooling pressure range for minimum combined-cycle-efficiency loss. At the end of the paper two-intercooled reheat-gas-turbine configurations are presented.

The Optimum Pressure Ratio for a Combined Cycle Gas Turbine Plant

1995 ◽  
Vol 209 (4) ◽  
pp. 259-264 ◽  
Author(s):  
J H Horlock
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Maximum Efficiency ◽  
Specific Work ◽  
Optimum Pressure ◽  
Turbine Plant ◽  
Gas Turbine Plant ◽  
Overall Efficiency ◽  
Gas Turbine Cycle

A graphical method of calculating the performance of gas turbine cycles, developed by Hawthorne and Davis (1), is adapted to determine the pressure ratio of a combined cycle gas turbine (CCGT) plant which will give maximum overall efficiency. The results of this approximate analysis show that the optimum pressure ratio is less than that for maximum efficiency in the higher level (gas turbine) cycle but greater than that for maximum specific work in that cycle. Introduction of reheat into the higher cycle increases the pressure ratio required for maximum overall efficiency.

The Evaporative Gas Turbine [EGT] Cycle

1997 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Mass Flow ◽  
Power Output ◽  
Pressure Ratio ◽  
Temperature Drop ◽  
Optimum Pressure ◽  
Flow Through ◽  
Gas Turbine Exhaust ◽  
Gas Turbine Cycle

Humidification of the flow through a gas turbine has been proposed in a variety of forms. The STIG plant involves the generation of steam by the gas turbine exhaust in a heat recovery steam generator [HRSG], and its injection into or downstream of the combustion chamber. This increases the mass flow through the turbine and the power output from the plant, with a small increase in efficiency. In the evaporative gas turbine [or EGT] cycle, water is injected in the compressor discharge in a regenerative gas turbine cycle [a so-called CBTX plant-compressor [C], burner [B], turbine [T], heat exchanger [X]]; the air is evaporatively cooled before it enters the heat exchanger. While the addition of water increases the turbine mass flow and power output, there is also apparent benefit in reducing the temperature drop in the exhaust stack. In one variation of the basic EGT cycle, water is also added downstream of the evaporative aftercooler, even continuously in the heat exchanger. There are several other variations on the basic cycle [e.g. the cascaded humidified advanced turbine (CHAT)]. The present paper analyses the performance of the EGT cycle. The basic thermodynamics are first discussed, and related to the cycle analysis of a dry regenerative gas turbine plant. Subsequently some detailed calculations of EGT cycles are presented. The main purpose of the work is to seek the optimum pressure ratio in the EGT cycle for given constraints [e.g. fixed maximum to minimum temperature]. It is argued that this optimum has a relatively low value.

Thermodynamic and Energy Study of a Regenerator in Gas Turbine Cycle and Optimization of Performances

2016 ◽  
Vol 5 (2) ◽  
pp. 25-44
Author(s):  
Saria Abed ◽  
Taher Khir ◽  
Ammar Ben Brahim
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Parametric Study ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Compressor Pressure Ratio ◽  
Compressor Inlet ◽  
Gas Turbine Cycle

In this paper, thermodynamic study of simple and regenerative gas turbine cycles is exhibited. Firstly, thermodynamic models for both cycles are defined; thermal efficiencies of both cycles are determined, the overall heat transfer coefficient through the heat exchanger is calculated in order to determinate its performances and parametric study is carried out to investigate the effects of compressor inlet temperature, turbine inlet temperature and compressor pressure ratio on the parameters that measure cycles' performance. Subsequently, numerical optimization is established through EES software to determinate operating conditions. The results of parametric study have shown a significant impact of operating parameters on the performance of the cycle. According to this study, the regeneration technique improves the thermal efficiency by 10%. The studied regenerator has an important effectiveness (˜ 82%) which improves the heat transfer exchange; also a high compressor pressure ratio and an important combustion temperature can increase thermal efficiency.

scholarly journals Investigation of the Pressure Gain Characteristics and Cycle Performance in Gas Turbines Based on Interstage Bleeding Rotating Detonation Combustion

Entropy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 265 ◽  
Author(s):  
Lei Qi ◽  
Zhitao Wang ◽  
Ningbo Zhao ◽  
Yongqiang Dai ◽  
Hongtao Zheng ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Cycle Performance ◽  
Efficiency Enhancement ◽  
Compressor Pressure Ratio ◽  
Detonation Combustion ◽  
Gas Turbine Cycle ◽  
Cycle Efficiency ◽  
Rotating Detonation

To further improve the cycle performance of gas turbines, a gas turbine cycle model based on interstage bleeding rotating detonation combustion was established using methane as fuel. Combined with a series of two-dimensional numerical simulations of a rotating detonation combustor (RDC) and calculations of cycle parameters, the pressure gain characteristics and cycle performance were investigated at different compressor pressure ratios in the study. The results showed that pressure gain characteristic of interstage bleeding RDC contributed to an obvious performance improvement in the rotating detonation gas turbine cycle compared with the conventional gas turbine cycle. The decrease of compressor pressure ratio had a positive influence on the performance improvement in the rotating detonation gas turbine cycle. With the decrease of compressor pressure ratio, the pressurization ratio of the RDC increased and finally made the power generation and cycle efficiency enhancement rates display uptrends. Under the calculated conditions, the pressurization ratios of RDC were all higher than 1.77, the decreases of turbine inlet total temperature were all more than 19 K, the power generation enhancements were all beyond 400 kW and the cycle efficiency enhancement rates were all greater than 6.72%.

Performance improvements of the recuperated gas turbine cycle using absorption inlet cooling and evaporative aftercooling

2002 ◽  
Vol 216 (4) ◽  
pp. 295-306 ◽  
Author(s):  
A. M. Bassily
Keyword(s):  
Gas Turbine ◽  
Parametric Study ◽  
Cooling System ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Temperature Ratio ◽  
Optimum Pressure ◽  
Performance Improvements ◽  
Gas Turbine Cycle ◽  
The Impact

An absorption inlet cooling system is introduced into the recuperated gas turbine cycle. The exhaust gases of the cycle are used to run the system. Five different layouts of the recuperated gas turbine cycle are presented. These include the effects of absorption inlet cooling, evaporative inlet cooling and evaporative cooling of compressor discharge (evaporative aftercooling), and the combined effect of absorption inlet cooling and evaporative aftercooling. A parametric study of the effect of pressure ratio, ambient temperature and relative humidity on the performance of all cycles is carried out. The results indicate that absorption inlet cooling could increase the efficiency of the recuperated cycle by up to 4 per cent, compared with 2.2 per cent for evaporative inlet cooling. Absorption inlet cooling with evaporative aftercooling could increase the optimum per efficiency of the recuperated cycle by up to 5 per cent and its maximum power by up to 65 per cent. Evaporative aftercooling reduces the impact of inlet cooling. Another parametric study of the effect of the turbine compressor inlet temperature ratio on the optimum pressure ratios indicated that cycles with evaporative aftercooling have higher optimum pressure ratios, which could be a function of the inlet temperature ratio and air temperature at the compressor outlet.

Thermodynamic Performance Analyses of Mixed Gas-Steam Cycle (2): A Case Study of Aeroderivative Gas Turbine

1998 ◽  
Author(s):  
Kirk Hanawa
Keyword(s):  
Gas Turbine ◽  
Steam Injection ◽  
Methanol Conversion ◽  
Combined Cycle ◽  
Mixed Gas ◽  
Kalina Cycle ◽  
Calculation Results ◽  
Gas Turbine Cycle ◽  
Typical Calculation

There are a plenty of proposals to aim the gas turbine cycle thermal efficiency of 60%, such as “Steam-Cooled H-Tech. Combined Cycle”, “Methanol Conversion Regenerative Gas Turbine”, “Kalina Cycle” etc.*1, *2, *4, *5, *6, *7 This paper discusses the predicted performance behaviors of an assumed aircraft-derivative GT of 60MW, when applying into mixed gas-steam cycles like STIG, ISTIG(Intercooled Steam Injection GT) with reasonable minor modifications from the assumed gas turbine. By making case studies of steam-injected binary cycles according to the established analyses method in Part (1), typical calculation results for getting 60% efficiency are presented. The water-injected at LPC, ISTIG cycle is equivalent or superior to other improvement ideas, offering several features listed below. 1) Unnecessary to have a bottoming cycle, saving a lot of investment for the related equipment 2) Quick and stable response for changing duty load, by injecting metered water and steam without air holding vessels like water-cooled heat exchangers

Numerical Modeling of Heat Transfer and Pressure Losses for Uncooled Gas Turbine Blade Tip: Effect of Tip Clearance and Tip Geometry

2007 ◽  
Author(s):  
Lamyaa A. El-Gabry
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Gas Turbine ◽  
Computational Study ◽  
Numerical Models ◽  
Pressure Ratio ◽  
Tip Clearance ◽  
Pressure Losses ◽  
Blade Tip ◽  
Exit Mach Number

A computational study has been performed to predict the heat transfer distribution on the blade tip surface for a representative gas turbine first stage blade. CFD predictions of blade tip heat transfer are compared to test measurements taken in a linear cascade, when available. The blade geometry has an inlet Mach number of 0.3 and an exit Mach number of 0.75, pressure ratio of 1.5, exit Reynolds number based on axial chord of 2.57×106, and total turning of 110 deg. Three blade tip configurations were considered; they are flat tip, a full perimeter squealer, and an offset squealer where the rim is offset to the interior of the tip perimeter. These three tip geometries were modeled at three tip clearances of 1.25, 2.0, and 2.75% of blade span. The tip heat transfer results of the numerical models agree fairly well with the data and are comparable to other CFD predictions in the open literature.

scholarly journals Thermodynamic Analysis of Different Configurations of Combined Cycle Power Plants

2015 ◽  
Vol 5 (2) ◽  
pp. 89
Author(s):  
Munzer S. Y. Ebaid ◽  
Qusai Z. Al-hamdan
Keyword(s):  
Gas Turbine ◽  
Power Plants ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Maximum Efficiency ◽  
Specific Work ◽  
Slight Effect ◽  
Turbine Engine ◽  
Gas Turbine Cycle ◽  
Cycle Efficiency

<p class="1Body">Several modifications have been made to the simple gas turbine cycle in order to increase its thermal efficiency but within the thermal and mechanical stress constrain, the efficiency still ranges between 38 and 42%. The concept of using combined cycle power or CPP plant would be more attractive in hot countries than the combined heat and power or CHP plant. The current work deals with the performance of different configurations of the gas turbine engine operating as a part of the combined cycle power plant. The results showed that the maximum CPP cycle efficiency would be at a point for which the gas turbine cycle would have neither its maximum efficiency nor its maximum specific work output. It has been shown that supplementary heating or gas turbine reheating would decrease the CPP cycle efficiency; hence, it could only be justified at low gas turbine inlet temperatures. Also it has been shown that although gas turbine intercooling would enhance the performance of the gas turbine cycle, it would have only a slight effect on the CPP cycle performance.</p>

scholarly journals Methanol Dissociative Intercooling in Gas Turbines

1982 ◽  
Author(s):  
M. F. Bardon ◽  
J. A. C. Fortin
Keyword(s):  
Carbon Monoxide ◽  
Theoretical Analysis ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Unit Mass ◽  
Cycle Model ◽  
Optimum Pressure ◽  
Heating Value ◽  
Compressor Work

This paper examines the possibility of injecting methanol into the compressor of a gas turbine, then dissociating it to carbon monoxide and hydrogen so as to cool the air and reduce the work of compression, while simultaneously increasing the fuel’s heating value. A theoretical analysis shows that there is a net reduction in compressor work resulting from this dissociative intercooling effect. Furthermore, by means of a computer cycle model, the effects of dissociation on efficiency and work per unit mass of airflow are predicted for both regenerated and unregenerated gas turbines. The effect on optimum pressure ratio is examined and practical difficulties likely to be encountered with such a system are discussed.

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