Study on the Sampling Quality of Wetness Measurement Probe for Thermodynamic Methods

2012 ◽  
Author(s):  
Xinjun Wang ◽  
Gaoliang Liao ◽  
Ding Zhu ◽  
Jinling Yao ◽  
Xiaowei Bai
Keyword(s):  
Water Droplet ◽  
Flow Direction ◽  
Droplet Diameter ◽  
Steam Flow ◽  
Stream Line ◽  
Inlet Section ◽  
Center Line ◽  
Water Droplets ◽  
Different Diameters ◽  
Nozzle Inlet

Software FLUENT was applied to conduct the numerical calculations of the sampling velocity at the sampling nozzle inlet of the wetness measurement probe and the trajectories of water droplets in the steam flow. The steam wetness of samples and the percentage of the droplets with different diameters entering the sampling nozzle were ascertained. The results showed that wetness measurement probe affected the flow of vapor phase at some degrees. Especially, there was a deflection of stream line nearby the sampling nozzle. It was showed that the isokinetic sampling could not be accomplished because of the viscosity of vapor. The larger the angle between the steam flow direction and the center line of the sampling nozzle was, the lower the average sampling velocity at sampling nozzle inlet section was. The percentage of water droplets captured by sampling nozzle increased with the augmentation of water droplet diameters. When the water droplet diameter was 5μm, the sampling nozzle would capture all water droplets in the corresponding area of the sampling nozzle inlet. When the sampling nozzle was dead against the upper stream, the wetness of sample extracted by sampling nozzle was lower than that of the measured steam. In contrast, the wetness of sample was larger than that of the measured steam when the angle between the sampling nozzle and upper stream was ± 5° or ± 10° respectively. The results have showed that the wetness error increased with the augmentation of sampling nozzle diameters, the vapor velocity and the angle between upper steam and center line of the sampling nozzle.

The Evaporation of Water Droplets in Superheated Steam

1968 ◽  
Vol 90 (4) ◽  
pp. 445-451 ◽  
Author(s):  
Kwan Lee ◽  
D. J. Ryley
Keyword(s):  
Reynolds Number ◽  
Glass Fiber ◽  
Water Droplet ◽  
Superheated Steam ◽  
Droplet Diameter ◽  
Steam Pressure ◽  
Water Droplets ◽  
Heating Up ◽  
Correlating Equation

The evaporation of a water droplet, diameter 230-1130μ, suspended on a 50μ diameter glass fiber was measured optically for the following range of variables: droplet Reynolds number 64-250, superheated steam pressure 14.7–29 psia, degrees of superheat 5–61 deg F; velocity 9–39 fps. The correlating equation was found to be Nu¯=2+0.74Re0.5Pr0.33 The apparatus and technique were proven using air as the evaporating medium. Calculations were made of the heating-up period at the beginning, and the drop asphericity at the end of a given test.

scholarly journals Numerical analysis of the steam flow field in shell and tube heat exchanger

2016 ◽  
Vol 37 (2) ◽  
pp. 107-120 ◽  
Author(s):  
Jarosław Bartoszewicz ◽  
Leon Bogusławski
Keyword(s):  
Heat Exchanger ◽  
Numerical Analysis ◽  
Flow Direction ◽  
Thermal Power ◽  
Turbulence Models ◽  
Steam Flow ◽  
Inlet Section ◽  
Tube Heat Exchanger ◽  
Numerical Studies ◽  
Shell And Tube

Abstract In the paper, the results of numerical simulations of the steam flow in a shell and tube heat exchanger are presented. The efficiency of different models of turbulence was tested. In numerical calculations the following turbulence models were used: k-ε, RNG k-ε, Wilcox k-ω, Chen-Kim k-ε, and Lam-Bremhorst k-ε. Numerical analysis of the steam flow was carried out assuming that the flow at the inlet section of the heat exchanger were divided into three parts. The angle of steam flow at inlet section was determined individually in order to obtain the best configuration of entry vanes and hence improve the heat exchanger construction. Results of numerical studies were verified experimentally for a real heat exchanger. The modification of the inlet flow direction according to theoretical considerations causes the increase of thermal power of a heat exchanger of about 14%.

Initial-Position-Driven Opposite Directional Transport of Water Droplet on Wedge-Shaped Groove

Nanoscale ◽  
2021 ◽  
Author(s):  
Shaoqian Hao ◽  
Xie Zhang ◽  
Zheng Li ◽  
Jianlong Kou ◽  
Fengmin Wu
Keyword(s):  
Water Droplet ◽  
Initial Position ◽  
Water Droplets ◽  
Transport Direction ◽  
Directional Transport ◽  
Prevailing View ◽  
Functionalized Surface

Transport direction of water droplets on a functionalized surface is of great significance due to its wide applications in microfluidics technology. The prevailing view is that a water droplet on...

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.

Geometrical parameters effect of recessed nozzle inlet section on the flow coefficient

2020 ◽  
Vol 27 (2) ◽  
pp. 140-148
Author(s):  
Andrey Sabirzyanov ◽  
Anna Kirillova ◽  
Chulpan Khamatnurova
Keyword(s):  
Flow Coefficient ◽  
Geometrical Parameters ◽  
Inlet Section ◽  
Nozzle Inlet

scholarly journals Numerical Simulation on Double-nozzle Spray Evaporation of Desulfurization Wastewater

2021 ◽  
Author(s):  
Hong Xu ◽  
Shuqin Feng ◽  
Liehui Xiao ◽  
Yazhen Hao ◽  
Xiaoze Du
Keyword(s):  
Flue Gas ◽  
Gas Flow ◽  
Evaporation Rate ◽  
Flow Direction ◽  
Droplet Diameter ◽  
Numerical Results ◽  
Least Square ◽  
Lagrangian Model ◽  
Support Vector ◽  
Exhaust Heat

To achieve the near zero emission of wastewater in the flue gas desulfurization (FGD) system in coal-fired power plant and better utilize the exhaust heat from flue gas, a feasible technology of spraying FGD wastewater in the flue duct for evaporation is discussed in the present study. A full-scale influencing factor investigation on the wastewater droplet evaporation performance is established under the Eulerian-Lagrangian model numerically. The dominant factors, including the characters of wastewater droplets, flue gas and the spray nozzles were analyzed under different conditions, respectively. Considering the multiple factors and conditions in the process, a Least-Square support vector machine (LSSVM) model is introduced to predict the evaporation rate based on the numerical results. Conclusions are made that the flue gas temperature and droplet diameter are of great importance in the evaporation process. The spray direction of droplet parallel with the flue gas flow direction is profitable for the dispersion of droplet, resulting the maximal evaporation rate. A double-nozzle arrangement optimized with relatively small flow rate is recommended. The LSSVM model can accurately predict the evaporation rate using the numerical results with different conditions.

A novel method for measuring the coarse water droplets in wet steam flow in steam turbines

2001 ◽  
Vol 10 (2) ◽  
pp. 123-126 ◽  
Author(s):  
Xiaoshu Cai ◽  
Lili Wang ◽  
Yongzhi Pan ◽  
Xin Ouyan ◽  
Jianqi Shen
Keyword(s):  
Steam Flow ◽  
Steam Turbines ◽  
Wet Steam ◽  
Water Droplets ◽  
Novel Method ◽  
Wet Steam Flow

Effects of Wet Compression on the Flow Behavior of a Centrifugal Compressor: A CFD Analysis

2014 ◽  
Author(s):  
Anish Surendran ◽  
Heuy Dong Kim
Keyword(s):  
Flow Rate ◽  
Water Droplet ◽  
Evaporation Rate ◽  
Pressure Ratio ◽  
Phase Flow ◽  
Water Droplets ◽  
Compression Process ◽  
Two Phase ◽  
Wet Compression ◽  
Injection Ratio

Wet compression has been emerging as a prominent method for augmenting net power output from land based gas turbine engine. It is proven more effective than the conventional inlet cooling methods. In this method, fine water droplets are injected just upstream of the compressor impeller. These water droplets absorb the latent heat of evaporation during the compression process of gas-water droplet two-phase flow, consequently reducing the temperature rise. Many gas turbine engineers have performed the feasibility and usefulness studies on this wet compression, but physical understanding on the wet compression process is highly lacking, and related compression flow mechanism remains ambiguous. In the present study, a computational fluid dynamics method has been applied to investigate the wet compression effects on a low speed centrifugal compressor. A Langrangian particle tracking method was employed to simulate the air-water droplet two-phase flow. The power saving achieved with different injection ratio of water droplets has been calculated and it is found that significant saving can be obtained with a water droplet injection ratio of above 3%. The vapor mass fraction varies linearly along the streamwise direction, making the assumption for a constant evaporation rate is valid. With the increase in the injection ratio the polytropic index for compression is coming down. The diffuser pressure recovery has been improved significantly with the wet compression; while the total pressure ratio across the impeller does not improve much. Contrary to the expectation, the evaporation rate is found to be coming down with the increase in the compressor mass flow rate. It is observed that the operating point, at which the peak pressure ratio occurs, shift towards higher mass flow rate during wet compression due to the local recirculation region within the vaneless space between the impeller and diffuser.

Vortices' Characteristics to Explain the Flange Height Effects on the Aerodynamic Performances of a Diffuser Augmented Wind Turbine

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Rym Chaker ◽  
Mouldi Kardous ◽  
Mahmoud Chouchen ◽  
Fethi Aloui ◽  
Sassi Ben Nasrallah
Keyword(s):  
Wind Velocity ◽  
Particle Image ◽  
Flow Direction ◽  
Pressure Coefficient ◽  
Inlet Section ◽  
Wind Tunnel Experiments ◽  
Piv Measurements ◽  
Velocity Increase ◽  
Image Velocimetry ◽  
Aerodynamic Performances

Flange height is between the geometric features that contribute efficiently to improve the diffuser aerodynamic performances. Results obtained from wind tunnel experiments, particle image velocimetry (PIV) measurements, and numerical simulations reveal that at the diffuser inlet section, the wind velocity increases as the flange height increases. Nevertheless, there is an optimal ratio (flange height/inlet section diameter, Hopt/Da ≈ 0.15) beyond it, the flange height effect on the velocity increase diminishes. This behavior can be explained by both the positions of the two contra-rotating vortices generated downstream of the diffuser and the pressure coefficient at their centers. Indeed, it was found that, as the flange height increases, the two vortices move away from each other in the flow direction and since the flange height exceeds (Hopt/Da), they became too distant from each other and from the flange. While the pressure coefficients at the vortices' centers increase with (H/Da), attain a maximum when (Hopt/Da) is reached, and then decrease. This suggests that the wind velocity increase depends on the pressure coefficient at the vortices' centers. Therefore, it depends on the vortices' locations which are in turn controlled by the flange height. In practice, this means that the diffuser could be more efficient if equipped with a control system able to hold the vortices too near from the flange.

scholarly journals Investigation of Regularities of Heat and Mass Transfer and Phase Transitions during Water Droplets Motion through High-Temperature Gases

2014 ◽  
Vol 6 ◽  
pp. 865856 ◽  
Author(s):  
Roman S. Volkov ◽  
Olga V. Vysokomornaya ◽  
Genii V. Kuznetsov ◽  
Pavel A. Strizhak
Keyword(s):  
Mass Transfer ◽  
Phase Transitions ◽  
High Temperature ◽  
Heat And Mass Transfer ◽  
Water Droplet ◽  
Small Neighborhood ◽  
Droplet Evaporation ◽  
Optical Methods ◽  
Water Droplets ◽  
Two Phase

The macroscopic regularities of heat and mass transfer and phase transitions during water droplets motion through high-temperature (more than 1000 K) gases have been investigated numerically and experimentally. Water droplet evaporation rates have been established. Gas and water vapors concentrations and also temperature values of gas-vapor mixture in small neighborhood and water droplet trace have been singled out. Possible mechanisms of droplet coagulation in high-temperature gas area have been determined. Experiments have been carried out with the optical methods of two-phase gas-vapor-droplet mixtures diagnostics (“Particle Image Velocimetry” and “Interferometric Particle Imaging”) usage to assess the adequateness of developed heat and mass transfer models and the results of numerical investigations. The good agreement of numerical and experimental investigation results due to integral characteristics of water droplet evaporation has been received.

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