An Assessment of High-Fogging Potential for Enhanced Compressor Performance

2006 ◽  
Author(s):  
Kyoung Hoon Kim ◽  
Horacio Perez-Blanco
Keyword(s):  
Gas Turbines ◽  
Water Injection ◽  
Transient Behavior ◽  
Transfer Model ◽  
Outlet Temperature ◽  
Compression Process ◽  
Mass Fractions ◽  
Parametric Studies ◽  
Wet Compression ◽  
Air Compression

Humidified gas turbines have the potential of enhanced cycle efficiencies with moderate initial cost. Evaporatively-cooled air compression is of importance to the power generation industry. The present work is aimed at contributing to a number of unanswered questions concerning the wet-compression process. Current operational margins limit the vapor mass fraction to 1∼2% by mass of the inlet flow. Yet, machines specifically designed to accommodate higher mass fractions are conceivable. Our aim is to explain the theoretical limits of those machines via a heat and mass transfer model. Continuous compression cooling via evaporation is modeled numerically based on droplet evaporation analysis. Parametric studies show the effect of variables such as droplet size, water injection ratio or compression ratio on transient behavior. Wet compression parameters such as evaporation time, compressor outlet temperature and compression work are estimated.

Performance Analysis of Wet Compression Process under Critical Conditions of Water Injection

2012 ◽  
Vol 229-231 ◽  
pp. 2541-2545
Author(s):  
Kyoung Hoon Kim ◽  
Chul Ho Han
Keyword(s):  
Performance Analysis ◽  
Ambient Temperature ◽  
Work Performance ◽  
Water Injection ◽  
Critical Conditions ◽  
Outlet Temperature ◽  
Ambient Conditions ◽  
Compression Process ◽  
Parametric Studies ◽  
Wet Compression

In wet compression process water is injected at an inlet of compressor and continuous cooling occurs due to evaporation of water droplets during the compression process of air, which can save the compression work and enhance the performance of gas turbine system. In this work, performance analysis of the wet compression process is carried out under the critical conditions of water injection which are defined as the maximum water injection which can be evaporated completely inside the compressor. For various ambient conditions the important variables of wet compression process such as water injection ratio, temperature-averaged polytropic coefficient, compressor outlet temperature, and compression work are estimated under the critical injection conditions. Parametric studies show that compression work decreases with ambient temperature, however, the reduction ratio of compression work relative to dry increases with ambient temperature.

An Assessment of Wet Compression Process in Gas Turbine Systems with an Analytical Modeling

2012 ◽  
Vol 234 ◽  
pp. 23-27
Author(s):  
Kyoung Hoon Kim ◽  
Dong Joo Kim ◽  
Kyoung Jin Kim ◽  
Seong Wook Hong
Keyword(s):  
Gas Turbine ◽  
Analytical Modeling ◽  
High Efficiency ◽  
Water Injection ◽  
Transient Behavior ◽  
Combined Cycle ◽  
Specific Power ◽  
Outlet Temperature ◽  
Compression Process ◽  
Wet Compression

Recently humidified gas turbine systems in which water or steam is injected have attracted much attention, since they can offer a high efficiency and a high specific power with a relatively low cost compared to combined-cycle gas turbine systems, and therefore they have a potential for future power generation. In this study, performance analysis of the wet compression process is carried out with an analytical modeling which was developed from heat and mass transfer, and thermodynamic analyses based on droplet evaporation. Wet compression variables such as temperature-averaged polytropic coefficient, compressor outlet temperature, and compression work are estimated. Parametric studies show the effect of system parameters such as droplet size, water injection ratio or compression ratio on transient behavior.

Flow Assessment on the Effects of Water Droplets on Rotor Region of Wet Compression

2017 ◽  
Vol 374 ◽  
pp. 131-147
Author(s):  
Gambo Kofar Bai Dayyabu ◽  
Hai Zhang ◽  
Qun Zheng ◽  
Salman Abdu
Keyword(s):  
Gas Turbine ◽  
Gas Flow ◽  
Fluid Dynamic ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Water Droplets ◽  
Compression Process ◽  
Transonic Compressor ◽  
Depth Analysis ◽  
Wet Compression

Wet compression process has been widely accepted as a measure of increasing the performance of industrial gas turbine, in the present work, in-depth analysis on the principle aspects of wet compression, more specifically, the influence of injected water droplets diameter, surface temperature, and their effects on the behavior of axial flow transonic compressor and gas turbine performance were analyzed using computational fluid dynamic. Injected water droplets and gas flow phase change was most intense in the area adjacent to shockwaves and were the slip velocity of the droplet is highest. Water injection in to the compressor rotor is a little perturbation to the flow field due to the formation of flow separation, evaporation rate, increasing weber number, reduction in the inlet temperature, and velocity vortex pattern relatively different from that of the dry case. The effects of water droplets on the rotor region at injection rate of 1%, shows decrease in the inlet temperature of 11%, outlet temperature 5% and uplift the efficiency to 1.5%.

Formation Process of Water Film and Performance Effect on Compressor Stage

2016 ◽  
Author(s):  
Hai Zhang ◽  
Xiaojiang Tian ◽  
Xiaojun Pan ◽  
Jie Zhou ◽  
Qun Zheng
Keyword(s):  
Gas Turbine ◽  
Formation Process ◽  
Water Injection ◽  
Water Film ◽  
Compressor Stage ◽  
Blade Surface ◽  
Water Droplets ◽  
Compression Process ◽  
Turbine Performance ◽  
Wet Compression

In process of wet compression, gas turbine engine will ingest a certain amount of water, which can influence the overall performance of the engine. This phenomenon is particularly significant in the cleaning process of industrial gas turbine and water injection of aero-engine. When the quantity of water ingestion is quite large, the performance of gas turbine will appear deterioration and may lead to flameout, power reduce or even shutdown of the engine, causing accidents. Water droplets will be accumulated on the blade surface where water films could be formed on pressure surface in the wet compression process. The effects of water film on gas turbine engines are aerodynamic, thermodynamic and mechanical. The above-mentioned effects occur simultaneously and be affected by each other. Considering the above effects and the fact that they are time dependent, there are few gas turbine performance researches, which take into account the water film phenomenon. This study is a new research of investigating theoretically the water film effects on a gas turbine performance. It focuses on the aerodynamic and thermodynamic effects of the phenomenon on the compressor stage. The computation of water film thickness, which frequently be formed on the surface of compressor blade, its movement and extra torque demand, are provided by a simulation model of the code. Considering the change in blade’s profile and the thickness feature of the water film, the compressor stage’s performance deterioration is analyzed. In addition to this, movement and the formation of the water film on a compressor stage are simulated and analyzed by using unsteady numerical methods under different water injecting conditions in this paper. The movement characteristics of water droplets in compressor passage are investigated to understand the flow mechanisms responsible for water film formation process. The forming and the tearing process of water film on blade surface are analyzed at different injection conditions. For simulating the real situation, The maximum quantity of injected water can reach 12%. The results indicate that continuity and region of the water film on the blade surface will be developed with the increment of droplet size and injection rate. It is also found that the flow losses near blade surface increases with the tearing process of water film due to the increment of surface roughness.

An Evaluation of the Effects of Water Injection on Compressor Performance

2003 ◽  
Author(s):  
A. J. White ◽  
A. J. Meacock
Keyword(s):  
Gas Turbines ◽  
Evaporative Cooling ◽  
Water Injection ◽  
Compression Process ◽  
Compressor Inlet ◽  
Design Behaviour ◽  
Industrial Gas Turbines ◽  
Compressor Performance ◽  
Compressor Work ◽  
The Impact

The injection of water droplets into compressor inlet ducting is now commonly used as a means of boosting the output from industrial gas turbines. The chief mechanisms responsible for the increase in power are the reduction in compressor work per unit flow and the increase in mass flow rate, both of which are achieved by evaporative cooling upstream of and within the compressor. This paper examines the impact of such evaporative processes on compressor operation, focussing particular attention on cases with substantial over-spray — i.e., for which significant evaporation takes place within the compressor itself, rather than in the inlet. A simple numerical method is described for the computation of wet compression processes, based on a combination of droplet evaporation and mean-line calculations. The method is applied to a “generic” compressor geometry in order to investigate the nature of the off-design behaviour that results from evaporative cooling. Consideration is also given to the efficiency of the compression process, the implications for choking and stall, and the magnitude of the thermodynamic loss resulting from irreversible phase change.

Stall and Surge in Wet Compression: Test Rig Development and Experimental Results

2018 ◽  
Author(s):  
Enrico Munari ◽  
Gianluca D’Elia ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Pier Ruggero Spina
Keyword(s):  
Gas Turbines ◽  
Water Injection ◽  
Experimental Results ◽  
Low Flow ◽  
Injection System ◽  
Data Sampling ◽  
Test Rig ◽  
State Tests ◽  
Dry Conditions ◽  
Wet Compression

Wet compression is a strategy adopted to increase the power output of gas turbines, with respect to dry conditions, usually also incrementing the operating range of the compressor. However, stall and surge are two aerodynamic instabilities which depend on many factors, and they are expected to occur even in wet compression at low flow rates. Despite the many studies carried out in the last 80 years, literature does not offer many works concerning these instability phenomena in wet compression. In this paper, an experimental analysis of stall and surge in wet compression conditions is carried out on an axial-centrifugal compressor installed in an existing test rig at the Engineering Department of the University of Ferrara. Some modifications of the test rig were necessary. The intake duct was implemented with a water injection system which, by means of water spray injectors, allows the uniform mixing of air and water before the compressor inlet. The control and data acquisition system of the test bench was updated with new hardware and software to obtain faster data sampling. Transient and steady-state tests were carried out to make a comparison with the experimental results in dry conditions. The analysis was carried out using traditional thermodynamic sensors, by means of both classic post-processing techniques, and cyclostationary analysis. The aim is to i) evaluate the influence of wet compression on the stable performance of the compressor ii) qualitatively identify the characteristics of stall and surge in wet compression by means of sensors which were shown to capture these phenomena well and iii) demonstrate the reliability of cyclostationary analysis in wet compression conditions for stall and surge analysis.

Gas Turbine Compressor Performance Characteristics During Wet Compression: Influence of Polydisperse Spray

2009 ◽  
Author(s):  
Rakesh K. Bhargava ◽  
Michele Bianchi ◽  
Mustapha Chaker ◽  
Francesco Melino ◽  
Antonio Peretto ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Performance Characteristics ◽  
Analytical Models ◽  
Lower Amount ◽  
Compression Process ◽  
Surge Margin ◽  
Compressor Performance ◽  
Wet Compression ◽  
The Impact

The available literature shows that there exists a lack of understanding about the impact of wet compression, involving two-phase flow, on the physics of flow in the compressor stages of a gas turbine engine. In recent years, analytical models have been proposed which provide effects of wet compression on the overall compressor performance and in few studies on the stage-by-stage performance. In spite of the fact that the wet compression technology for power augmentation has been commercially implemented on numerous gas turbines from all the major gas turbine manufacturers, many issues such as, effects of polydisperse spray, droplets dynamics, influence on the performance characteristics of individual stages, stage and overall surge margin, etc., remain not completely understood. This investigation clearly shows importance of considering effects of polydisperse spray on the overall and stage-by-stage compressor performance characteristics. The presented results show that for a given droplets distribution and ambient condition, later stages of a compressor are prone to reduced surge margin under wet compression process due to redistribution of stage loading. Moreover, the study shows that smaller distributions allow the achievement of higher performance, but the compressor surge is reached with a lower amount of injected water.

Prediction of Evaporative Effects Within the Blading of an Industrial Axial Compressor

2008 ◽  
Author(s):  
Charles Matz ◽  
Wolfgang Kappis ◽  
Giovanni Cataldi ◽  
Gerd Mundinger ◽  
Stefan Bischoff ◽  
...  
Keyword(s):  
Mass Flow ◽  
Gas Turbines ◽  
Water Injection ◽  
Flow Analysis ◽  
Axial Compressor ◽  
Surface Flow ◽  
Water Evaporation ◽  
Airfoil Surface ◽  
Flow Angle ◽  
Wet Compression

The results of a compressor flow-analysis code calibration study for estimating the effects of water evaporation within the blade rows of industrial axial compressors are presented. In the study, a mean-line code was chosen for the calibration tool due to its accepted use during preliminary design studies, at which time during the compressor design process one would logically consider power augmentation through wet compression. The calibrated code features a non-equilibrium thermodynamic single-droplet evaporation model augmented with an empirical splashing model, which, as input, uses measurements of droplet spectra data taken on water injection nozzles in an intake rig configured with realistic length scales. In addition, a wetted-airfoil-surface flow angle deviation model is applied to predict changes in compressor stage characteristics, which, in turn, affect the inlet mass flow of the compressor. The test vehicle for calibration was a 50-Hz Alstom industrial gas turbine. Once calibrated, the code was successfully utilized to predict wet compression effects for three additional like-family Alstom gas turbines operating at constant speed while under full load. The effects modeled by the code include bleed supply pressure suck-down and bleed temperature cool-down effects, as well as compressor inlet mass flow and power consumption effects.

An Evaluation of the Effects of Water Injection on Compressor Performance

2004 ◽  
Vol 126 (4) ◽  
pp. 748-754 ◽  
Author(s):  
A. J. White ◽  
A. J. Meacock
Keyword(s):  
Gas Turbines ◽  
Evaporative Cooling ◽  
Water Injection ◽  
Droplet Evaporation ◽  
Compression Process ◽  
Compressor Inlet ◽  
Industrial Gas Turbines ◽  
Compressor Performance ◽  
Compressor Work ◽  
The Impact

The injection of water droplets into compressor inlet ducting is now commonly used as a means of boosting the output from industrial gas turbines. The chief mechanisms responsible for the increase in power are the reduction in compressor work per unit flow and the increase in mass flow rate, both of which are achieved by evaporative cooling upstream of and within the compressor. This paper examines the impact of such evaporative processes on compressor operation, focussing particular attention on cases with substantial overspray—i.e., for which significant evaporation takes place within the compressor itself, rather than in the inlet. A simple numerical method is described for the computation of wet compression processes, based on a combination of droplet evaporation and mean-line calculations. The method is applied to a “generic” compressor geometry in order to investigate the nature of the off-design behavior that results from evaporative cooling. Consideration is also given to the efficiency of the compression process, the implications for choking and stall, and the magnitude of the thermodynamic loss resulting from irreversible phase change.

Wet Compression Analysis Including Velocity Slip Effects

2010 ◽  
Author(s):  
A. J. White ◽  
A. J. Meacock
Keyword(s):  
Gas Turbines ◽  
Velocity Slip ◽  
Design Flow ◽  
Compression Process ◽  
Relaxation Effects ◽  
Slip Effects ◽  
Industrial Gas Turbines ◽  
Wet Compression ◽  
Dry Climates ◽  
The Impact

Injection of water droplets into industrial gas turbines in order to boost power output is now common practice. The intention is usually to saturate and cool the intake air, especially in hot and dry climates, but in many cases droplets carry over into the compressor and continue to evaporate. Evaporation within the compressor itself (often referred to as “overspray”) is also central to several advanced wet cycles, including the Moist Air Turbine (MAT) and the so-called TOPHAT cycle. The resulting wet compression process affords a number of thermodynamic advantages, such as reduced compression work, and increased mass flow rate and specific heat capacity of the turbine flow. Against these benefits, many of the compressor stages will operate at significantly off-design flow angles, thereby compromising aerodynamic performance. The current paper describes wet compression calculations including velocity slip and many of the associated phenomena (e.g., blade deposition and film evaporation). The calculations also allow for a poly-dispersion of droplet sizes and droplet temperature relaxation effects (i.e., the full droplet energy equation is solved rather than assuming that droplets adopt the wet-bulb temperature). The latter is important for sprays produced by “flashing” since the resulting droplets are initially much hotter than the surrounding gas. The method has been applied to a “generic” twelve stage compressor to ascertain to the impact slip effects have on the wet compression process.

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