scholarly journals Temperature Compensation for Conductivity-Based Phase Fraction Measurements with Wire-Mesh Sensors in Gas-Liquid Flows of Dilute Aqueous Solutions

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7114
Author(s):  
Philipp Wiedemann ◽  
Felipe de Assis Dias ◽  
Eckhard Schleicher ◽  
Uwe Hampel
Keyword(s):  
Temperature Effects ◽  
Temperature Compensation ◽  
Phase Distribution ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Wire Mesh ◽  
Effect Of Temperature ◽  
Experimental Investigations ◽  
Fluid Temperature ◽  
Two Phase

Wire-mesh sensors are well-established scientific instruments for measuring the spatio-temporal phase distribution of two-phase flows based on different electrical conductivities of the phases. Presently, these instruments are also applied in industrial processes and need to cope with dynamic operating conditions increasingly. However, since the quantification of phase fractions is achieved by normalizing signals with respect to a separately recorded reference measurement, the results are sensitive to temperature differences in any application. Therefore, the present study aims at proposing a method to compensate temperature effects in the data processing procedure. Firstly, a general approach is theoretically derived from the underlying measurement principle and compensation procedures for the electrical conductivity from literature models. Additionally, a novel semi-empirical model is developed on the basis of electrochemical fundamentals. Experimental investigations are performed using a single-phase water loop with adjustable fluid temperature in order to verify the theoretical approach for wire-mesh sensor applications and to compare the different compensation models by means of real data. Finally, the preferred model is used to demonstrate the effect of temperature compensation with selected sets of experimental two-phase data from a previous study. The results are discussed in detail and show that temperature effects need to be handled carefully—not merely in industrial applications, but particularly in laboratory experiments.

scholarly journals Current Advances in Ejector Modeling, Experimentation and Applications for Refrigeration and Heat Pumps. Part 2: Two-Phase Ejectors

Inventions ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 16 ◽  
Author(s):  
Zine Aidoun ◽  
Khaled Ameur ◽  
Mehdi Falsafioon ◽  
Messaoud Badache
Keyword(s):  
Heat Pumps ◽  
Operating Conditions ◽  
Industrial Processes ◽  
Experimental Investigations ◽  
Mixing Enhancement ◽  
Data Generation ◽  
Two Phase ◽  
Wide Range ◽  
Potential Applications ◽  
And Performance

Two-phase ejectors play a major role as refrigerant expansion devices in vapor compression systems and can find potential applications in many other industrial processes. As a result, they have become a focus of attention for the last few decades from the scientific community, not only for the expansion work recovery in a wide range of refrigeration and heat pump cycles but also in industrial processes as entrainment and mixing enhancement agents. This review provides relevant findings and trends, characterizing the design, operation and performance of the two-phase ejector as a component. Effects of geometry, operating conditions and the main developments in terms of theoretical and experimental approaches, rating methods and applications are discussed in detail. Ejector expansion refrigeration cycles (EERC) as well as the related theoretical and experimental research are reported. New and other relevant cycle combinations proposed in the recent literature are organized under theoretical and experimental headings by refrigerant types and/or by chronology whenever appropriate and systematically commented. This review brings out the fact that theoretical ejector and cycle studies outnumber experimental investigations and data generation. More emerging numerical studies of two-phase ejectors are a positive step, which has to be further supported by more validation work.

The Modeling of Flow Concentration in Two-Phase Materials

1976 ◽  
Vol 98 (2) ◽  
pp. 180-189 ◽  
Author(s):  
T. S. Cook ◽  
C. A. Rau ◽  
E. Smith
Keyword(s):  
Development Program ◽  
High Strength ◽  
Theoretical Models ◽  
Operating Conditions ◽  
Micromechanical Modeling ◽  
High Yield ◽  
Experimental Investigations ◽  
Two Phase ◽  
Wide Range ◽  
Materials Research

Many high strength alloys that are developed for arduous operating conditions have essentially a two-phase microstructure that is produced by a precipitation-hardening procedure. However, alloys that are heat-treated to have maximum hardness, often have poor monotonic and poor fatigue fracture characteristics when these are assessed in relation to their high yield strengths, and this imposes limits to their use for service applications. Experimental investigations covering a wide range of precipitation-hardened alloys have shown that the inferior fracture properties are due to plastic deformation being concentrated within narrow zones. Against this background, Pratt & Whitney Aircraft is undertaking a comprehensive theoretical investigation based on the representation of flow concentration by appropriate theoretical models. The general objective is to provide a quantitative understanding of flow concentration, both with respect to its causes and consequences, in terms of both material and externally imposed parameters such as, for example, the state of loading. The aim of the present paper is not to survey the complete problem of flow concentration in the light of the research undertaken to date, but to provide a limited number of examples that illustrate how specific aspects of the problem have been considered using appropriate models to describe the operative physical processes. With the Conference’s objectives in mind, the paper’s general intention is therefore to provide further evidence that micromechanical modeling can be successfully used to relate mechanical behavior with metallurgical parameters, and thereby add further support for the view that such work forms an integral part of any balanced materials research and development program.

Experimental Investigation of Horizontal Gas–Liquid Stratified and Annular Flow Using Wire-Mesh Sensor

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Ronald E. Vieira ◽  
Netaji R. Kesana ◽  
Carlos F. Torres ◽  
Brenton S. McLaury ◽  
Siamack A. Shirazi ◽  
...  
Keyword(s):  
Void Fraction ◽  
Test Section ◽  
Annular Flow ◽  
Parameter Extraction ◽  
Industrial Applications ◽  
Wire Mesh ◽  
Process Equipment ◽  
Two Phase ◽  
Cross Sectional ◽  
Horizontal Pipe

Stratified and annular gas–liquid flow patterns are commonly encountered in many industrial applications, such as oil and gas transportation pipelines, heat exchangers, and process equipment. The measurement and visualization of two-phase flow characteristics are of great importance as two-phase flows persist in many fluids engineering applications. A wire-mesh sensor (WMS) technique based on conductance measurements has been applied to investigate two-phase horizontal pipe flow. The horizontal flow test section consisting of a 76.2 mm ID pipe, 18 m long was employed to generate stratified and annular flow conditions. Two 16 × 16 wire configuration sensors, installed 17 m from the inlet of the test section, are used to determine the void fraction within the cross section of the pipe and determine interface velocities between the gas and liquid. These physical flow parameters were extracted using signal processing and cross-correlation techniques. In this work, the principle of WMS and the methodology of flow parameter extraction are described. From the obtained raw data time series of void fraction, cross-sectional mean void fraction, time averaged void fraction profiles, interfacial structures, and velocities of the periodic structures are determined for different liquid and gas superficial velocities that ranged from 0.03 m/s to 0.2 m/s and from 9 m/s to 34 m/s, respectively. The effects of liquid viscosity on the measured parameters have also been investigated using three different viscosities.

scholarly journals An Experimental Investigation of Thermal Effects in a Cavitating Inducer

2004 ◽  
Vol 126 (5) ◽  
pp. 716-723 ◽  
Author(s):  
Jean-Pierre Franc ◽  
Claude Rebattet ◽  
Alain Coulon
Keyword(s):  
Thermal Effects ◽  
Cavity Length ◽  
Cold Water ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Operating Conditions ◽  
Fluid Temperature ◽  
Two Phase ◽  
Thermodynamic Effect ◽  
Comparison Of Tests

The thermal effects which affect the development of leading edge cavitation in an inducer were investigated experimentally using refrigerant R114. For different operating conditions, the evolution of the cavity length with the cavitation parameter was determined from visualizations. The tests were conducted up to two-phase breeding. The comparison of tests in R114 and in cold water allowed us to estimate the amplitude of the thermodynamic effect. The results show that the B-factor depends primarily upon the degree of development of cavitation but not significantly upon other parameters such as the inducer rotation speed or the fluid temperature, at least in the present domain of investigation. These trends are qualitatively in agreement with the classical entrainment theory. In addition, pressure fluctuations spectra were determined in order to detect the onset of cavitation instabilities and particularly of alternate blade cavitation and rotating cavitation. If the onset of alternate blade cavitation appeared to be connected to a critical cavity length, the results are not so clear concerning the onset of rotating cavitation.

Images Analysis of Horizontal Two-Phase Slug Flows

2011 ◽  
Author(s):  
R. E. M. Morales ◽  
M. J. da Silva ◽  
E. N. Santos ◽  
L. Dorini ◽  
C. E. F. do Amaral ◽  
...  
Keyword(s):  
High Speed ◽  
Oil And Gas Industry ◽  
Industrial Applications ◽  
Wire Mesh ◽  
Bubble Velocity ◽  
Internal Diameter ◽  
Two Phase ◽  
Experimental Conditions ◽  
Flow Measurements ◽  
Slug Flows

Multi-phase flow measurements are very common in industrial applications especially of the oil and gas industry. In order to study such pattern one can apply many different techniques such as capacitive probes, X-ray and gamma ray tomography, ultrasound transducers, wire-mesh sensors and high speed videometry. This article describes experimental study of water-air slug in horizontal pipes through non-intrusive image analysis technique. A flow test section comprising of a pipe of 26 mm internal diameter and 9 m long was employed to generate slug flows under controlled conditions. The behavior of the flow was studied using gas and liquid velocities between 0.3 m/s and 2 m/s with 6000 images (500×232 pixels) for each case. The algorithm comprises the automatic analysis of a sequence of frames in MatLab to measure flow characteristics such as Taylor bubble velocity and frequency applying morphological treatment. Finally, the parameters measured through the high speed videometry were compared with theoretical predictions showing that such method can be used to validate other types of sensors in experimental conditions.

CFD Simulations Devoted to the Study of Fitting Effects on the Phase Distribution in Parallel Vertical Channels

2015 ◽  
Vol 13 (4) ◽  
pp. 551-559 ◽  
Author(s):  
F. Devia ◽  
A. Marchitto ◽  
M. Fossa ◽  
G. Guglielmini
Keyword(s):  
Heat Exchangers ◽  
Single Phase ◽  
Phase Distribution ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Two Phase Flows ◽  
Cfd Simulations ◽  
Two Phase ◽  
Compact Heat Exchangers ◽  
Dynamic Performances

Abstract Uneven distribution of phases in plate heat exchangers is a cause of reduction in both thermal and fluid-dynamic performances. With respect to two-phase flows, phase separation in manifolds with several outlets is a complex phenomenon and no general rules are available for predicting the phase distribution at header–channel junctions. The design of compact heat exchangers and their distributors is still based on empirical approaches and both experimentation and numerical analyses are needed for defining the best geometries able to reduce the mass flow rate non-uniformities in parallel channels. In this paper, a series of CFD simulations are carried out to infer the effects of a protrusion fitting (inside the header) on the single-phase distribution in parallel upward vertical channels fed by a common horizontal distributor. The numerical results are compared with both experimental single-phase and two-phase (liquid/gas) experimental data. The effects of the operating conditions are investigated and general conclusions on the differences and analogies between single-phase and two-phase flows in the present problem are discussed.

Investigation of Leakage Rates in Pressure Retaining Piping

2017 ◽  
Author(s):  
Fabian E. Silber ◽  
Xaver Schuler ◽  
Stefan Weihe ◽  
Eckart Laurien ◽  
Rudi Kulenovic ◽  
...  
Keyword(s):  
Power Plants ◽  
Leak Detection ◽  
Operating Conditions ◽  
Leak Rate ◽  
Test Facility ◽  
Experimental Investigations ◽  
Two Phase ◽  
Detection Systems ◽  
Test Loop ◽  
Calculation Models

Within the break preclusion concept, leak-before-break (LBB) behavior must be demonstrated for safety relevant pressure retaining piping systems in nuclear power plants (NPP) [1]. This requires leak detection systems in NPP with the capability to detect leak rates below the maximum allowable leak rate calculated by the LBB assessment according to nuclear standards, like the German KTA rule 3206 or the U.S. Standard Review Plan (SRP). An important part of the LBB assessment is the availability of accurate calculation models to predict the leak rate under normal operating conditions for postulated through wall cracks. Current leak detection systems in NPP are capable of reliably detecting liquid leak rates 0.05 kg/s. However, most of the available experimental leak rate data published in literature focus on the range between 0.2 kg/s and 2 kg/s, which is significantly above the detection limit. Therefore, additional experimental investigations are necessary to develop and verify leak rate calculation models for smaller leaks. In order to investigate such types of leaks, a modular test facility (fluid-structure-interaction test loop) has been developed and installed at MPA University of Stuttgart within the framework of a research project sponsored by the German Ministry of Education and Research (BMBF). The test rig includes a leakage piping module which includes artificially machined slits and fatigue through-wall cracks. It allows the variation of the significant influencing parameters such as crack size, surface roughness and the system parameters pressure and temperature up to 75 bar and 280 °C and also the measurement of the pressure gradient across the crack surface at two locations. This is important to develop a better understanding of the two-phase flow and pressure drop across the leak channel. A first test series has been performed and the results were used to evaluate existing leak-rate models. Within this paper an overview of the test facility, the testing procedure, and the results of the investigations will be presented and discussed.

The Effect of Outlet Inclination on Two-Phase Flow Splitting in an Equal-Sided Impacting Tee Junction

2010 ◽  
Author(s):  
M. A. Mohamed ◽  
H. M. Soliman ◽  
G. E. Sims
Keyword(s):  
Phase Distribution ◽  
Operating Conditions ◽  
Distribution Data ◽  
Flow Loop ◽  
Two Phase ◽  
Split Ratio ◽  
Flow Splitting ◽  
Tee Junction ◽  
Inlet Conditions ◽  
Full Separation

Phase-distribution data have been generated for two-phase (air-water) flow splitting at an impacting tee junction with a horizontal inlet and inclined outlets. This investigation also considers the full-separation capabilities of the junction and the effect of the outlet angle of inclination on partial separation at various inlet conditions. A flow loop with the ability to incline the outlets from −90° downward to +90° upward was constructed. The operating conditions were as follows: test-section inside diameter of 13.5 mm, nominal junction pressure (Ps) of 200 kPa (abs), near ambient temperature (Ts), inlet superficial gas velocities (JG1) ranging from 2.0 to 40 m/s, inlet superficial liquid velocities (JL1) ranging from 0.01 to 0.18 m/s, mass split ratios (W3/W1) from 0 to1.0 and inlet flow regimes of stratified, wavy, and annular. The data reveal that the degree of maldistribution of the phases depended on the inlet conditions, the mass split ratio at the junction, and the inclination angle of the outlets.

Characterisation of Air-Water Two-Phase Flow Using a Wire-Mesh Sensor

2011 ◽  
Author(s):  
Carlos E. F. do Amaral ◽  
O´liver B. S. Scorsim ◽  
Eduardo N. Santos ◽  
Marco Jose´ da Silva ◽  
Marco Germano Conte ◽  
...  
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Industrial Applications ◽  
Wire Mesh ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Rates ◽  
Piping Systems

Two phase flow occurs in many industrial applications, mainly in the transport of mixtures. Many patterns can be produced according to the liquid and gas flow rates. The identification of these patterns is very important in the design of piping systems and equipments. This work proposes an experimental study to identify multiphase flow patterns of water and air in horizontal pipes. The study was developed using an experimental circuit of 26 mm diameter and 9.2 m length pipe, at Thermal Sciences Lab (LACIT) at the Federal University of Technology - Parana´. To characterize the flow patterns, an intrusive mesh electrodes sensor was used, which allows the detailed visualization of the phases distribution. Tests were made using several experimental settings of water and gas flow rates. Measurements were compared to images obtained by high speed camera and the temporal void fraction series which were analyzed with the use of PDF and PSD functions, showing the singularities for each two-phase flow pattern.

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