Investigation Of Multiphase Flow Research Articles

Radon transport carried by geogas: prediction model.

This paper provides an overview and information on radon migration in the crust. In the past several decades, numerous studies on radon migration have been published. However, there is no there is no comprehensive review of large-scale radon transport in the earth crust. A literature review was conducted to present the research on the mechanism of radon migration, geogas theory, investigation of multiphase flow, and modeling method of fractures. Molecular diffusion was long considered the primary mechanism for radon migration in the crust. However, a molecular diffusion mechanism cannot explain the understanding of anomalous radon concentrations. In contrast with early views, the process of radon migration and redistribution within the Earth may be determined by geogas (mainly CO2 and CH4). Microbubbles rising in fractured rocks may be a rapid and efficient way of radon migration, as reported by recent studies. All these hypotheses on the mechanisms of geogas migration are summarized into a theoretical framework, defined as "geogas theory." According to geogas theory, fractures are the principal channel of gas migration. The development of the discrete fracture network (DFN) method is expected to supply a new tool for fracture modeling. It is hoped that this paper will contribute to a deeper understanding of radon migration and fracture modeling.

Efficient Surrogate-Assisted Parameter Analysis for Coal-Supercritical Water Fluidized Bed Reactor with Adaptive Sampling

Supercritical water fluidized beds (SCWFBs) are promising and efficient reactors for the gasification of coal in supercritical water. The understanding and investigation of multi-phase flows as well as the gasification process usually rely on time-consuming experiments or numerical simulations, which prohibit fast and full exploration of the single and coupled effects of the operation and geometric parameters. To this end, this paper builds an efficient surrogate-assisted parameter analysis framework for the SCWFB reactor. Particularly, (1) it establishes a steady numerical simulation model of the SCWFB reactor for the subsequent analysis; and (2) it employs a Gaussian process surrogate modeling via efficient adaptive sampling to serve as an approximation for predicting the carbon conversion efficiency (CE) of the reactor. Based on this parameter analysis framework, this paper investigates the effects of five independent parameters (the mass flow rate of supercritical water, mass flow rate of the coal slurry, temperature of supercritical water, temperature of the outer wall and reactor length) and their interactions on the reaction performance in terms of the carbon conversion efficiency (CE). We found that the CE increases as a function of the temperature of supercritical water, the temperature of the outer wall and the reactor length; while it decreases as a function of the mass flow rate of supercritical water and the mass flow rate of the coal slurry. Additionally, the global sensitivity analysis demonstratesthat the influence of the temperature of the outer wall exerts a stronger effect than all the other factors on the CE, and the coupled interaction among parameters has a slight effect on the CE. This research provides useful guidance for scaled-up designs and optimization of the SCWFB reactor.

Investigation of Argon Blowing in a Steel-Teeming Ladle

We present the results of numerical and full-scale experiments aimed at the investigation of multiphase flows and interface processes in the volume of a commercial 160-ton steel-teeming ladle in the process of blowing with argon through the porous bottom plugs. We develop a mathematical model capable of prediction of the degree of denudation of melt “mirror” from the slag cover caused by the variations of the argon flow rate. We also established the regularities of changes in the influence of argon flow rate within the range 40--120 liter/min on the sizes of the domain of washout of the slag and the behavior of the sizes of stagnation zones in the volume of the ladle. It is shown that the maximum increase in efficiency is observed as the argon flow rate increases from 40 to 60 liter/min. The results of simulations are compared with the data of full-scale tests carried out at the Novolipetsk Iron-and-Steel Works.

Film thickness planar sensor in oil-water flow: prospective study

Purpose – The purpose of this paper is to study a multiphase-flow instrumentation for film thickness measurement, especially impedance-based, not only for gas–liquid flow but also for mixtures of immiscible and more viscous substances such as oil and water. Conductance and capacitive planar sensors were compared to select the most suitable option for oil – water dispersed flow. Design/methodology/approach – A study of techniques for measurement of film thickness in oil – water pipe flow is presented. In the first part, some measurement techniques used for the investigation of multiphase flows are described, with their advantages and disadvantages. Next, examinations of conductive and capacitive techniques with planar sensors are presented. Findings – Film thickness measurement techniques for oil–water flow are scanty in the literature. Some techniques have been used in studies of annular flow (gas–liquid and liquid–liquid flows), but applications in other flow patterns were not encountered. The methods based on conductive or capacitive measurements and planar sensor are promising solutions for measuring time-averaged film thicknesses in oil–water flows. A capacitive system may be more appropriate for oil–water flows. Originality/value – This paper provides a review of film thickness measurements in pipes. There are many reviews on gas – liquid flow measurement but not many about liquid – liquid flow.

ICOPE-15-C018 Investigation of multiphase flow and reaction process in SG-Vortex gasifier

ICOPE-15-C018 Investigation of multiphase flow and reaction process in SG-Vortex gasifier

Investigation of Multiphase Flows on Inclined Plates as Potential Design Tool for Separation Devices

AbstractFlüssigkeiten strömen in verfahrenstechnischen Apparaten häufig in Form von Filmen und Rinnsalen. Das grundlegende Verständnis der Stoffübergangsvorgänge in diesen meist unter 1 mm dicken Strömungen ist von wesentlicher Bedeutung für die Auslegung von Apparaten. Dabei können wichtige Erkenntnisse zur Strömungsform und zum Stoffübergang bereits an einfachen Platten gewonnen werden. In Basisuntersuchungen wird der Einfluss von Oberflächenstrukturen auf den Stoffübergang und auf das Strömungsfeld experimentell nachgewiesen. Die Ergebnisse könnten künftig für die Validierung von CFD‐Modellen und die signifikante Weiterentwicklung von eingesetzt werden.

Kapazitäts-Gittersensor: Prinzip und AnwendungCapacitance Wire-Mesh Sensor: Principle and Application

Zusammenfassung Gittersensoren ermöglichen räumlich und zeitlich hochaufgelöste Untersuchungen von Mehrphasenströmungen und können für viele strömungsdiagnostische Probleme eingesetzt werden. Dieser Beitrag beschreibt den neu entwickelten Kapazitäts-Gittersensor, welcher auf der Messung der elektrischen Permittivität (Kapazität) basiert. Neben der Beschreibung des Messprinzips und der dazugehörigen Messelektronik sowie Datenanalyse wird auch ein ausgewähltes Anwendungsbeispiel präsentiert. Der Gittersensor wurde bei der Untersuchung einer zweiphasigen Öl-Gas-Rohrströmung eingesetzt, wobei die Strömungsregime visualisiert und einige wichtige quantitative Strömungsparameter aus den gemessenen Rohdaten extrahiert wurden.

Sequencing batch reactor (SBR) as optimal method for production of granular activated sludge (GAS) – fluid dynamic investigations

Fluid dynamic investigations of multiphase flow (fluid, air, granules) in a sequencing batch reactor (SBR) are presented. SBR can be considered as an attractive technology for cultivation of granular activated sludge (GAS). Granulation is a complicated process and its mechanism is not fully understood yet. Many factors influence the formation and structure of aerobic granular sludge in a bioreactor. Extracellular polymer substances (EPS) and superficial gas velocity (SGV) play a crucial role for granules formation. Additionally, it is supposed that EPS production is stimulated by mechanical forces. It is also assumed that hydrodynamic effects have a major influence on the formation, shape and size of GAS in SBR under aerobic condition. However, the influence of stress on granulation is poorly investigated. Thus, in the present paper, fluid dynamic investigations of multiphase flow in a SBR, particularly effect of normal and shear strain, are reported. In order to analyse multiphase flow in the SBR, optical in-situ techniques with particle image velocimetry (PIV) and particle tracking velocimetry (PTV) are implemented. Obtained results show a characteristic flow pattern in a SBR. It is pointed out that additional effects like particle-wall collisions, inter particle collisions, erosion can also affect significantly granules formation.

Investigation of multiphase flow in sequencing batch reactor (SBR) by means of hybrid methods

An analysis of a sequencing batch reactor (SBR) from a fluid mechanical point of view, used in the cultivation of granular activated sludge (GAS), is carried out by experimental, computational fluid dynamics (CFD) and artificial neuronal networks (ANN) methods. Due to the complexity of the three-phase problem, new hybrid methods are developed in order to shorten the calculation time and to improve the numerical prediction. In the numeroexperimental hybrid, experimentally obtained velocities from particle image velocimetry (PIV) method are implemented as initial conditions for the numerical simulation. This operation causes improvement of multiphase flow results and save CPU time of about 40% in comparison with the standard calculation. In the neuronumerical hybrid, numerically obtained results and process parameters are employed for training of an ANN. With the trained ANN, several geometrical and physical entities are calculated for a range of SBRs. In this case, the acceleration, in the prediction of several process parameters, reaches the factor 1.0 E + 05 .

Application of a geocentrifuge and sterolithographically fabricated apertures to investigations of multiphase flow in complex fracture apertures

A geotechnical centrifuge was used to investigate unsaturated multiphase fluid flow in synthetic fracture apertures under a variety of flow conditions. The geocentrifuge subjected the fluids to centrifugal forces allowing the Bond number to be systematically changed without adjusting the fracture aperture or the fluids. The fracture models were based on the concept that surfaces generated by the fracture of brittle geomaterials have a self-affine fractal geometry. The synthetic fracture surfaces were fabricated from a transparent epoxy photopolymer using sterolithography, and fluid flow through the transparent fracture models was monitored by an optical image acquisition system. Aperture widths were chosen to be representative of the wide range of geological fractures in the vesicular basalt that lies beneath the Idaho National Laboratory (INL). Transitions between different flow regimes were observed as the acceleration was changed under constant flow conditions. The experiments showed the transition between straight and meandering rivulets in smooth walled apertures (aperture width= 0.508 mm), the dependence of the rivulet width on acceleration in rough walled fracture apertures (average aperture width = 0.25 mm), unstable meandering flow in rough walled apertures at high acceleration (20 g) and the narrowing of the wetted region with increasing acceleration during the penetration of water into an aperture filled with wetted particles (0.875 mm diameter glass spheres).

The Prediction of Pressure Loss During Two-Phase Horizontal Flow in Two-Inch Pipe

This investigation of multiphase flow, supported jointly by the Texas Petroleum Research Committee, The University of Texas, and many companies affiliated with the oil industry, is an effort to develop a reliable method of predicting static pressure loss during two-phase horizontal flow in 2-in. pipe. The 165 two-phase tests were run in 1688 ft of 2-in. steel line pipe with water, distillate, and crude oil in connection with natural gas. The liquid flow rate ranged from 50 to 2500 B/D, with gas rates up to 6 MMscf/D. The range of mean line pressures was from 70 to 850 psig. Pressures were measured at 12 line locations, the liquid holdup was measured at two locations, and flow patterns were photographed through plastic pipe sections. From the data, correlations have been developed for liquid holdup and for an energy loss factor. The correlations can be used in conjunction with a derived equation to predict two-phase horizontal pressure losses. The prediction method is carefully outlined and, although it lends itself to computer usage, it is relatively fast and just as accurate by hand. Applied to the original data, the method yielded pressure gradients with an average error of 2.3 percent.