scholarly journals Systematic Frequency and Statistical Analysis Approach to Identify Different Gas–Liquid Flow Patterns Using Two Electrodes Capacitance Sensor: Experimental Evaluations

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2932 ◽  
Author(s):  
Fayez M. Al-Alweet ◽  
Artur J. Jaworski ◽  
Yusif A. Alghamdi ◽  
Zeyad Almutairi ◽  
Jerzy Kołłątaj
Keyword(s):  
Flow Patterns ◽  
Liquid System ◽  
Operating Conditions ◽  
Total Power ◽  
Capacitance Sensor ◽  
Statistical Parameters ◽  
Two Phase ◽  
Power Spectral ◽  
Flow Apparatus ◽  
Gas Liquid Flow

This work proposes a method to distinguish between various flow patterns in a multiphase gas–liquid system. The complete discrimination between different flow patterns can be achieved by mapping the corresponding frequency and statistical parameters. These parameters are usually obtained from further analysis conducted on the signal data of the utilized sensor. The proposed technique is based on establishing interrelationships between these parameters, namely the mean (m), the standard deviation ( σ ¯ ), power spectral density (PSD), the width of the characteristic frequency peaks (Δƒ), the skewness ( γ 1 ) and the kurtosis ( γ 2 ). Therefore, a relatively simple electrical capacitance sensor with two electrodes was designed and implemented on a two-phase flow apparatus with a circular pipe. The experimental operating conditions comprised of different combinations of air–water superficial velocities at three inclinations (i.e., horizontal, upward 15° and upward 30°). This research discusses in specific the analysis underlying flow patterns identification method and the rationale for selecting the proposed approach. The results showed that some parameters found to be more valuable than others such as m, σ ¯ and Δƒ. Besides, combining two sets of these statistical graphs which are (a) σ ¯ vs. Δƒ with Δƒ vs. m (or Δƒ vs. total power), (b) Δƒ vs. total power with γ 1 vs. σ ¯ (or γ 2 vs. σ ¯ ), and (c) σ ¯ vs. m with Δƒ vs. m (or Δƒ vs. total power), allowed all flow patterns field to be identified clearly at all inclinations. It is therefore concluded that for any gas–liquid multiphase flow system, the reported approach can be used reliably to discriminate between different generated flow patterns.

Visualization of the Heat Transfer Enhancement During Condensation in a Microfin Tube

2006 ◽  
Author(s):  
Alberto Cavallini ◽  
Davide Del Col ◽  
Luca Doretti ◽  
Simone Mancin ◽  
Luisa Rossetto ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Saturation Temperature ◽  
Flow Patterns ◽  
Operating Conditions ◽  
Vapor Quality ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Plain Tube ◽  
The Heat Transfer Coefficient

Microfins tubes are largely used in refrigeration industry for in-tube refrigerant condensation, because of the heat transfer enhancement when compared to equivalent smooth tubes under the same operating conditions. But not much evidence about the effect of microfins on the condensation flow patterns is available in the open literature. There is agreement in the open literature that the mechanisms of heat transfer are intimately linked with the prevailing two-phase flow regime. The present authors have recently measured the heat transfer coefficient during condensation of R410A in a microfin tube. The heat transfer enhancement in this tube can be experimentally evaluated by comparing those coefficients to the ones measured by Cavallini et al. (2001) in a plain tube, at the same operating conditions. The same operative conditions (saturation temperature, vapor quality and mass flux), occurring during the heat transfer measurements, were reproduced in a different section for visualization of flow patterns during condensation of R410A. The flow visualization has been carried out both in the plain tube and in the microfin tube. The objective of the present paper is to present the heat transfer enhancement during condensation of R410A and to show the flow visualized at the same operating condition for both the smooth and the microfin tube, aiming to link the heat transfer enhancement to the flow pattern variation.

Experimental Study on Flow Patterns of Decaying Swirling Gas-Liquid Flow in a Horizontal Pipe

2020 ◽  
Author(s):  
Shuai Liu ◽  
Li Liu ◽  
Jiarong Zhang ◽  
Hanyang Gu
Keyword(s):  
Flow Pattern ◽  
Liquid Flow ◽  
Separation Efficiency ◽  
Swirling Flow ◽  
Flow Patterns ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Gas Removal ◽  
Swirl Vane ◽  
Gas Liquid Flow

Abstract Swirling flow is one of the well-recognized techniques to control the working process. This special flow is widely adopted in swirl vane separators in nuclear steam generator (SG) for water droplet separation and the fission gas removal system in Thorium Molten Salt Reactor (TMSR) for gas bubble separation. Since the parameters such as separation efficiency, pressure drop and mass and heat transfer rate are strongly dependent on the flow pattern, the accurate prediction of flow patterns and their transitions is extremely important for the proper design, operation and optimization of swirling two-phase flow systems. In this paper, using air and water as working fluids, a visualization experiment is carried out to study the gas-liquid flow in a horizontal pipe containing a swirler with four helical vanes. The test pipe is 5 m in length and 30 mm in diameter. Firstly, five typical flow patterns of swirling gas-liquid flow at the outlet of the swirler are classified and defined, these being spiral chain, swirling gas column, swirling intermittent, swirling annular and swirling ribbon flow. Being affected by the different gas and liquid flow rate of non-swirling flow, it is found that the same non-swirling flow can change into different swirling flow patterns. After that, the evolution of various swirling flow patterns along the streamwise direction is analyzed considering the influence of swirl attenuation. The results indicate that the same swirling flow pattern can transform into a variety of swirling flow patterns and subsequent non-swirling flow patterns. Finally, the flow pattern maps at different positions downstream of the swirler are presented.

Effect of Fluid Properties on Flow Patterns in Two-Phase Gas−Liquid Flow in Horizontal and Downward Pipes†

2011 ◽  
Vol 50 (2) ◽  
pp. 645-655 ◽  
Author(s):  
Christina Tzotzi ◽  
Vasilis Bontozoglou ◽  
Nikolaos Andritsos ◽  
Michael Vlachogiannis
Keyword(s):  
Liquid Flow ◽  
Flow Patterns ◽  
Two Phase ◽  
Fluid Properties ◽  
Gas Liquid Flow

Flow Visualization of Unsteady and Transient Phenomena in a Mixed-Flow Multiphase Pump

2016 ◽  
Author(s):  
Alberto Serena ◽  
Lars E. Bakken
Keyword(s):  
Two Phase Flow ◽  
Flow Patterns ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Homogeneous Distribution ◽  
Phase Flow ◽  
Two Phase ◽  
Inlet Flow ◽  
Transient Phenomena ◽  
Multiphase Pump

The flow inside of turbomachines rotating channels, when operating away from the design point, is intrinsically unsteady; two-phase flow and part-load operation further complicate the analysis, introducing additional challenges. Transient phenomena, linked to the typical unsteadiness of multiphase flows (bubble formation, coalescence or breakdown, segregation and gas locking) and to variable inlet flow compositions, as in case of slug flow, require advanced analysis tools which can reveal the local flow mechanisms responsible for performance degradation and instabilities. General trends can be outlined, but the air accumulation zones and two-phase flow patterns are highly dependent on the machine design. The flow regimes vary from a homogeneous distribution of fine bubbles, evenly dispersed and carried away by the main flow, to more complex flow patterns, especially when the phases separate or the bubbles coalesce forming a gas pocket which adheres to a wide portion of the channel wall. Tests are performed on a multiphase pump laboratory, recently installed at the Norwegian University of Science and Technology, which allows a complete optical access to the pump channels and fine adjustments in the inlet configuration and the tip clearance gap; the air can be injected from different locations producing transient regimes too. A high speed camera provides an interesting insight into the transient flow phenomena. This paper focuses on these specific ones: - Irregular backflow and swirl at the inlet section - Gas accumulation zones and contribution of the tip leakage to mixing - Flow pattern shift to phase segregation, as the relative flow is reduced - Origin of pump blockage, when increasing gas contents cannot be carried away by the water phase - Flow and machine parameters response to a variation in the inlet flow Tests are performed at various operating conditions — rotational speed, mixture composition and impeller tip clearance. The study is completed with the time and frequency domain analysis of the pressure pulsations at surging and during specific transient events.

ANN-based prediction of two-phase gas- liquid flow patterns in a circular conduit

AIChE Journal ◽  
2006 ◽  
Vol 52 (9) ◽  
pp. 3018-3028 ◽  
Author(s):  
H. Sharma ◽  
G. Das ◽  
A. N. Samanta
Keyword(s):  
Liquid Flow ◽  
Flow Patterns ◽  
Two Phase ◽  
Gas Liquid Flow

Terminal Slugcatchers for Two-Phase Flow and Dense-Phase Flow Gas Pipelines

1988 ◽  
Vol 110 (4) ◽  
pp. 224-229
Author(s):  
L. Oranje
Keyword(s):  
Flow Behavior ◽  
Operating Conditions ◽  
Design Stage ◽  
Phase Flow ◽  
Basic Design ◽  
Dense Phase ◽  
Two Phase ◽  
Technical Specifications ◽  
Gas Liquid Flow

Slugcatchers are installed at the end of two-phase pipelines and dense-phase pipelines. The technical specifications of a slugcatcher for a two-phase pipeline are based on the gas-liquid flow behavior at the various operating conditions. For a dense-phase pipeline these specifications are derived from the flow behavior in the pipeline during depressurization. These flow studies, which are carried out in the design stage of a transmission system, should be sufficiently accurate to provide proper sizing of the transmission line and slugcatcher. The paper deals with: • the methods and the quality of these methods for calculating the flow behavior in a two-phase pipeline and in a dense-phase pipeline—a comparison of both types of transmission systems is given; • the basic design of a terminal slugcatcher, including some causes of possible malfunctioning—an optimal design of a terminal slugcatcher is also discussed.

scholarly journals The Influence on Response of a Combined Capacitance Sensor in Horizontal Oil–Water Two-Phase Flow

2019 ◽  
Vol 9 (2) ◽  
pp. 346 ◽  
Author(s):  
Lei Li ◽  
Lingfu Kong ◽  
Beibei Xie ◽  
Xin Fang ◽  
Weihang Kong ◽  
...  
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Capacitance Sensor ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Response Characteristics ◽  
Oil Water ◽  
Water Cut

In the process of production logging interpretation, a water cut is one of the key factors to obtain the oil phase content in the oil well. In order to measure the water cut of the horizontal oil–water two-phase flow with low yield, the response characteristics of the combined capacitance sensor (CCS) are investigated under different flow patterns. Firstly, the measuring principles of coaxial, cylindrical, and CCS are introduced in detail. Then, according to the different flow pattern conditions of the horizontal oil–water two-phase flow, the response characteristics of the CCS are simulated and analyzed using the finite element method. Additionally, compared with the other two sensors, the advantages of the CCS are verified. Finally, the temperature and pressure calibration experiments are carried out on the CCS. The horizontal oil–water two-phase flow patterns in a low yield liquid level are divided in detail with a high-speed camera. Dynamic experiments are carried out in a horizontal pipe with an inner diameter of 125 mm on the horizontal oil–water two-phase flow experimental equipment. The simulation and experimental results show that the CCS has good response characteristics under different working conditions.

Gas-Liquid Flow Through Horizontal Eccentric Annuli: CFD and Experiments Compared

2011 ◽  
Author(s):  
Mehmet Sorgun ◽  
Reza E. Osgouei ◽  
M. Evren Ozbayoglu ◽  
A. Murat Ozbayoglu
Keyword(s):  
Liquid Flow ◽  
High Speed ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Flow Patterns ◽  
Phase Flow ◽  
Cfd Model ◽  
Flow Loop ◽  
Two Phase ◽  
Gas Liquid Flow

Although flow of two-phase fluids is studied in detailed for pipes, there exists a lack of information about aerated fluid flow behavior inside a wellbore. This study aims to simulate gas-liquid flow inside horizontal eccentric annulus using an Eulerian-Eulerian computational fluid dynamics (CFD) model for two-phase flow patterns i.e., dispersed bubble, dispersed annular, plug, slug, churn, wavy annular. To perform experiments using air-water mixtures for various in-situ air and water flow rates, a flow loop was constructed. A digital high speed camera is used for recording each test dynamically for identification of the liquid holdup and flow patterns. Results showed that CFD model predicts frictional pressure losses with an error less than 20% for all two-phase flow patterns when compared with experimental data.

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