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 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.

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%.

The Control of NOx and CO Emissions From 7-MW Gas Turbines With Water Injection as Influenced by Ambient Conditions

1985 ◽  
Author(s):  
W. S. Y. Hung ◽  
D. D. Agan
Keyword(s):  
Ambient Temperature ◽  
Gas Turbines ◽  
Water Injection ◽  
Field Measurements ◽  
Field Testing ◽  
Ambient Air ◽  
Injection System ◽  
Ambient Conditions ◽  
Water Control ◽  
Fuel Gas

Interpretation of federal emissions regulations by a local regulatory agency resulted in the requirement to develop a special water control system for stationary gas turbines to meet stringent NOx and CO emissions limits. Extensive field testing of two 7-MW industrial gas turbines burning natural gas was performed to establish the effects of ambient air temperature, humidity and water injection on NOx and CO emissions. The predictions from a proven NOx model were shown to be within the uncertainty of the field measurements and were used to determine the water flow rates required when burning No. 2 distillate oil. Over the ambient temperature range considered, the analytical model predicted a linear increase in NOx emissions as ambient temperature increases. This was supported by the data gathered and the thermal NOx rate equation. Subsequently, a water injection system was successfully developed to control NOx and CO emissions from the 7-MW dual fuel gas turbine as a function of ambient temperature and turbine load.

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 Entropy Based Evaluation of Efficiency of a Transonic Compressor Rotor With Water Injection

2008 ◽  
Author(s):  
Istvan Szabo ◽  
Mark G. Turner
Keyword(s):  
Viscous Dissipation ◽  
Entropy Generation ◽  
Dissipation Function ◽  
Entropy Generation Rate ◽  
Thermodynamic Efficiency ◽  
Compression Process ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Wet Compression ◽  
Isentropic Efficiency

Defining the thermodynamic efficiency of the wet compression process in a compressor is not trivial, since the flow in this case has multiple phases present which interact with each other. In this paper, an approach is presented that calculates the overall entropy creation and thus the isentropic efficiency of a wet compression process in a transonic compressor rotor. The viscous dissipation function is calculated everywhere in the domain in the post-processing phase of the CFD simulation and integrated to the wall, with special treatment in the near-wall regions where high rates of entropy generation occur. The isentropic efficiency of the wet compression is then determined from the entropy generation rate. Analytical integration of wall functions and numerical integration of the viscous dissipation function allows for reasonable results even with relatively coarse grids and can be applied for single-phase flows. The methodology presented is also useful to quantify the efficiency of thermodynamic processes in devices that introduce streams into the flow path, such as cooled turbines and compressors with flow control.

Influence of Water Droplet Size and Temperature on Wet Compression

2007 ◽  
Author(s):  
M. Bianchi ◽  
F. Melino ◽  
A. Peretto ◽  
P. R. Spina ◽  
S. Ingistov
Keyword(s):  
Gas Turbine ◽  
Water Droplet ◽  
Droplet Diameter ◽  
Axial Compressor ◽  
Combined Cycle ◽  
Water Evaporation ◽  
Air Cooling ◽  
Compression Process ◽  
Two Phase ◽  
Wet Compression

In the last years, among all different gas turbine inlet air cooling techniques, an increasing attention to fogging approach is dedicated. The various fogging strategies seem to be a good solution to improve gas turbine or combined cycle produced power with low initial investment cost and less installation downtime. In particular, overspray fogging and interstage injection involve two-phase flow consideration and water evaporation during compression process (also known as wet compression). According to the Author’s knowledge, the field of wet compression is not completely studied and understood. In the present paper, all the principal aspects of wet compression and in particular the influence of injected water droplet diameter and surface temperature, and their effect on gas turbine performance and on the behavior of the axial compressor (change in axial compressor performance map due to the water injection, redistribution of stage load, etc.) are analyzed by using a calculation code, named IN.FO.G.T.E. (INterstage FOgging Gas Turbine Evaluation), developed and validated by the Authors.

Heat Transfer Analysis of Room-Temperature Finned-Tube Evaporator for Cryogenic Nitrogen

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Shun Ching Lee ◽  
Tzu-Min Chen
Keyword(s):  
Heat Flux ◽  
Room Temperature ◽  
Integrated Model ◽  
Finned Tube ◽  
Heat Transfer Analysis ◽  
Outlet Temperature ◽  
Ambient Conditions ◽  
Governing Equations ◽  
Initial Value ◽  
Two Phase

Abstract The behavior of cryogenic nitrogen in a room-temperature evaporator six meters long is analyzed. Trapezoid fins are employed to enhance the heat flux supplied by the environment. The steady-state governing equations specified by the mixed parameters are derived from the conservations of momentum and energy. The initial value problem is solved by space integration. The fixed ambient conditions are confirmed by way of the meltback effect. An integrated model is utilized to analyze the convective effect of two-phase flow, which dominates the evaporation behavior. Another integrated model is employed to determine the total heat flux from the environment to the wet surface of the evaporator. The foundation of the formation of an ice layer surrounding the evaporator is presented. If the fin height is shorter than 0.5 m, the whole evaporator is surrounded by ice layer. If the fin height is longer than 0.5 m, the total pressure drop of nitrogen in the tube is negligible. The outlet temperature is always within the range between −12 °C and 16 °C for the evaporator with the fin height of 1.0 m. For the evaporator with dry surface, the nitrogen has the outlet temperature less than the ambient temperature at least by 5 °C.

Gas Turbine Corrected Parameters Control: Humidity Correction – Sensors Evaluation and Selection

2002 ◽  
Author(s):  
Malath I. Arar
Keyword(s):  
Gas Turbine ◽  
Water Injection ◽  
Specific Humidity ◽  
Inlet Temperature ◽  
Ambient Conditions ◽  
Humidity Measurement ◽  
Nox Abatement ◽  
Test Criterion ◽  
Control Methodology ◽  
Performance Enhancing

Gas Turbine, GT, control methodology applied to power generation is being evaluated. Corrected parameter control methodology has been adopted for this purpose. This method uses the corrected physical ambient conditions such as pressure, temperature and humidity in controlling the GT operations. Humidity correction becomes increasingly important in this control scheme. The following are the reasons for accurate and robust humidity measurement: (1) Humidity measurement is important to the operation control of the dry low NOX, DLN, combustor system. (2) GT inlet performance enhancing devices, such as evaporative coolers and inlet foggers, depend upon the accurate humidity measurement to determine the amount of water needed for inlet temperature depression. (3) Humidity measurement is used to determine the amount of water to be injected in the combustor for NOX abatement when running on liquid fuel as an alternative to natural gas fuel. In order to obtain accurate and reliable humidity readings, several commercially available humidity sensors were extensively tested and evaluated in a controlled laboratory environment. The sensors were tested for their measurement accuracy, saturation conditions, power interruption and surge, sudden temperature changes and medium air speed. Test ambient temperature ranges from −30 °C to 50 °C. This covers the operating ambient conditions range for the Gas Turbine. The test criterion is that the error in the response of the sensor shall not exceed ±1 °C from the test reference for all the tests conducted on the sensors. The combustion requirements for Dry Low NOX operations and mode transfer dictate this criterion. Also, as a DLN requirement, error in specific humidity shall not exceed 0.904 g/g of air. This test criterion also satisfies the water injection requirements for NOX abatement and inlet performance enhancing devices. The results show that for ±1 °C error in the sensor measurement, the resulting error in NOX calculation is less than 0.2 ppm. The test results show that all sensors except the current one in use have met the test criterion. The current sensor, General Eastern DT-2, has a large measurement error in the order of ±5 °C. Programs have been launched to field test and evaluate these sensors in order to replace the current one.

Performance Analysis and Optimization of Fresnel Lens Concentrated Solar Water Heater

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Vinod Kumar Soni ◽  
R. L. Shrivastava ◽  
S. P. Untawale ◽  
Kshitij Shrivastava
Keyword(s):  
Life Cycle ◽  
Performance Analysis ◽  
Flat Plate ◽  
Mass Flow ◽  
Critical Parameters ◽  
Total System ◽  
Outlet Temperature ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water

Concentrated solar power (CSP) is a mature and efficient technology to cater the large-scale demand of hot water. Conventional reflectors/mirrors in CSP share 50% of total system cost. High installation as well as O&M cost is the major concern in reflector-based CSP. Apart from the above, manufacturing defects and adverse service environment cause premature degradation of reflectors and substantial drop in efficiency and service life. Performance analysis of an innovative optically concentrated solar water heater (OCSWH) using plurality of Fresnel lenses of poly methyl methacrylate (PMMA) is presented in the work. Size and yield of any solar water heater (SWH) are mainly dependent on its aperture area, output temperature, and mass flow rate, which are termed herein as critical parameters. Series of experimentations is carried out by varying critical design and operating parameters viz. aperture area, outlet temperature, and rate of mass flow, and similar experimentation is also carried out on commercially available flat plate SWH to compare its performance. Loss of heat from riser and header pipes is restricted by application of effective insulation. Substantial improvement in collector efficiency, increase in rate of mass flow, and rise in discharge temperature with reference to flat plate collector are noted. Economics is also studied covering life cycle cost (LCC), life cycle saving (LCS), and energy payback period.

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