Numerical Simulation of Gas-Liquid Two-Phase Flows on Wetted Walls

2010 ◽  
Author(s):  
Yoshiyuki Iso ◽  
Xi Chen
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Liquid Flow ◽  
Film Flow ◽  
Liquid Flow Rate ◽  
Flow Transition ◽  
Wall Surface ◽  
Two Phase ◽  
Wall Flows ◽  
Rivulet Flow

Gas-liquid two-phase flows on the wall like liquid film flows, which are the so-called wetted wall flows, are observed in many industrial processes such as absorption, desorption, distillation and others. For the optimum design of packed columns widely used in those kind of processes, the accurate predictions of the details on the wetted wall flow behavior in packing elements are important, especially in order to enhance the mass transfer between the gas and liquid and to prevent flooding and channeling of the liquid flow. The present study focused on the effects of the change of liquid flow rate and the wall surface texture treatments on the characteristics of wetted wall flows which have the drastic flow transition between the film flow and rivulet flow. In this paper, the three-dimensional gas-liquid two-phase flow simulation by using the volume of fluid (VOF) model is applied into wetted wall flows. Firstly, as one of new interesting findings in this paper, present results showed that the hysteresis of the flow transition between the film flow and rivulet flow arose against the increasing or decreasing stages of the liquid flow rate. It was supposed that this transition phenomenon depends on the history of flow pattern as the change of curvature of interphase surface which leads to the surface tension. Additionally, the applicability and accuracy of the present numerical simulation were validated by using the existing experimental and theoretical studies with smooth wall surface. Secondary, referring to the texture geometry used in an industrial packing element, the present simulations showed that surface texture treatments added on the wall can improve the prevention of liquid channeling and can increase the wetted area.

Gas-Liquid Two-Phase Flow Simulation of Wetted Wall Flows in Packed Columns

2010 ◽  
Author(s):  
Yoshiyuki Iso ◽  
Xi Chen
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Film Flow ◽  
Liquid Flow Rate ◽  
Flow Simulation ◽  
Phase Flow ◽  
Flow Transition ◽  
Two Phase ◽  
Wall Flows ◽  
Rivulet Flow

Gas-liquid two-phase interfacial flows on the wall like liquid film flows, which are the so-called wetted wall flows, are observed in many industrial processes such as absorption, desorption, and distillation. For the optimum design of packed columns widely used in those kind of processes, the accurate predictions of the details on the small scale behavior of wetted wall flows in packing elements are very important, especially in order to enhance the mass transfer between the gas and liquid and to prevent flooding and channeling of the liquid flow. The present study focuses on the effects of the change of liquid flow rate and the wall surface texture treatments on the characteristics of wetted wall flows which have the drastic flow transition between the film flow and rivulet flow. In this paper, the three-dimensional gas-liquid two-phase flow simulation by using the volume of fluid (VOF) model is applied into wetted wall flows. Firstly, present results showed that the hysteresis of the flow transition between the film flow and rivulet flow arose against the increasing or decreasing stages of the liquid flow rate. It was supposed that this transition phenomenon depends primarily on the history of flow pattern as the change of curvature of interphase surface which leads to the surface tension. Additionally, the applicability and accuracy of the present numerical simulation were validated by using the existing experimental and theoretical studies. Secondary, referring to the texture geometry used in an industrial packing element, the present simulations showed that surface texture treatments added on the wall can improve the prevention of liquid channeling and can increase the wetted area.

Flow Transition Behavior of the Wetting Flow Between the Film Flow and Rivulet Flow on an Inclined Wall

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Yoshiyuki Iso ◽  
Xi Chen
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Surface Texture ◽  
Film Flow ◽  
Liquid Flow Rate ◽  
Flow Simulation ◽  
Surface Shape ◽  
Two Phase ◽  
Vof Model ◽  
Rivulet Flow

Gas-liquid two-phase interfacial flows, such as the liquid film flows (also known as wetting flows on walls), are observed in many industrial processes including absorption, desorption, distillation, and so on. The present study focuses on the characteristics of wetting flows, in particular the drastic transition between the film flow and rivulet flow, as the liquid flow rate and the wall surface texture treatments are varied. The three-dimensional gas-liquid two-phase interfacial flow (wetting flow) simulation is based on the volume of fluid (VOF) model. As the liquid flow rate is increased and then decreased, a hysteresis of the transition between the film flow and rivulet flow is discovered, which implies that the transition phenomenon depends primarily on the history of the change of interfacial surface shape (which affects the process of the flow pattern transition). The applicability and accuracy of the present numerical simulation is validated by using the existing experimental and theoretical studies. Further study on the effect of texture geometry shows that the surface texture treatments added on the wall can impede liquid channeling and increase the wetted area.

Experimental Study of Turbulent Swirling Flow in a Vertical Tube for Heat Transfer Enhancement Using Ultrasonic Velocity Profiler (UVP)

2015 ◽  
Author(s):  
Ari Hamdani ◽  
Nobuyoshi Tsuzuki ◽  
Hiroshige Kikura
Keyword(s):  
Ultrasonic Velocity ◽  
Void Fraction ◽  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Swirling Flow ◽  
Wire Mesh ◽  
Twisted Tape ◽  
Wall Region ◽  
Two Phase

Two-phase swirling flow through a pipe is a complex turbulent flow and its prediction is still challenging. The present paper describes the experimental investigation of the air-water two phase swirling flow in vertical co-current flow. Swirling flow is induced by a twisted tape in a 20 mm inner diameter pipe. The flow is investigated using Ultrasonic Velocity Profiler (UVP), which allows the measurement of liquid and gas velocities simultaneously. Furthermore, simultaneous measurement of void fraction is performed using Wire Mesh Sensor (WMS). The experimental results reveal that swirling flow has significant impact on bubbles’ distribution. In low liquid flow rate, the average bubble velocity is fairly uniform along the radial position and void fraction increases in the near wall region. However, increasing liquid flow rate at constant gas flow rate leads to increase in void fraction in the core region, this is mainly due to drift velocity which is affected by centrifugal force. Experimental findings and parametric trends based on the effects of swirling flow are summarized and discussed.

Wet Gas Flow Metering Based on Differential Pressure and BSS Techniques

2011 ◽  
Vol 383-390 ◽  
pp. 4922-4927
Author(s):  
Peng Xia Xu ◽  
Yan Feng Geng
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Liquid Flow Rate ◽  
Differential Pressure ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Metering ◽  
Wet Gas

Wet gas flow is a typical two-phase flow with low liquid fractions. As differential pressure signal contains rich information of flow parameters in two-phase flow metering, a new method is proposed for wet gas flow metering based on differential pressure (DP) and blind source separation (BSS) techniques. DP signals are from a couple of slotted orifices and the BSS method is based on time-frequency analysis. A good relationship between the liquid flow rate and the characteristic quantity of the separated signal is established, and a differential pressure correlation for slotted orifice is applied to calculate the gas flow rate. The calculation results are good with 90% relative errors less than ±10%. The results also show that BSS is an effective method to extract liquid flow rate from DP signals of wet gas flow, and to analysis different interactions among the total DP readings.

Design and Performance of Slug Damper

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Antonio Reinoso ◽  
Luis E. Gomez ◽  
Shoubo Wang ◽  
Ram S. Mohan ◽  
Ovadia Shoham ◽  
...  
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Liquid Velocity ◽  
Flow Behavior ◽  
Mechanistic Model ◽  
Gas Velocity ◽  
Flow Loop ◽  
Two Phase ◽  
Superficial Gas Velocity

This study investigates theoretically and experimentally the slug damper as a novel flow conditioning device, which can be used upstream of compact separation systems. In the experimental part, a 3 in. ID slug damper facility has been installed in an existing 2 in. diameter two-phase flow loop. This flow loop includes an upstream slug generator, a gas-liquid cylindrical cyclone (GLCC©, ©The University of Tulsa, 1994) attached to the slug damper downstream and a set of conductance probes for measuring the propagation of the dissipated slug along the damper. Over 200 experimental runs were conducted with artificially generated inlet slugs of 50 ft length (Ls/d=300) that were dumped into the loop upstream of the slug damper, varying the superficial liquid velocity between 0.5 ft/s and 2.5 ft/s and superficial gas velocity between 10 ft/s and 40 ft/s (in the 2 in. inlet pipe) and utilizing segmented orifice opening heights of 1 in., 1.5 in., 2 in., and 3 in. For each experimental run, the measured data included propagation of the liquid slug front in the damper, differential pressure across the segmented orifice, GLCC liquid level, GLCC outlet liquid flow, and static pressure in the GLCC. The data show that the slug damper/GLCC system is capable of dissipating long slugs, narrowing the range of liquid flow rate from the downstream GLCC. Also, the damper capacity to process large slugs is a strong function of the superficial gas velocity (and mixture velocity). The theoretical part includes the development of a mechanistic model for the prediction of the hydrodynamic flow behavior in the slug damper. The model enables the predictions of the outlet liquid flow rate and the available damping time, and in turn the prediction of the slug damper capacity. Comparison between the model predictions and the acquired data reveals an accuracy of ±30% with respect to the available damping time and outlet liquid flow rate. The developed model can be used for design of slug damper units.

scholarly journals CFD Modeling of Gas-Liquid Flow and Heat Transfer in a High Pressure Water Electrolysis System

2006 ◽  
Author(s):  
V. Agranat ◽  
S. Zhubrin ◽  
A. Maria ◽  
J. Hinatsu ◽  
M. Stemp ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Water Electrolysis ◽  
Phase Flow ◽  
Cfd Model ◽  
Two Phase ◽  
Pressure Water ◽  
Electrolysis System

A high-pressure water electrolysis system has been investigated numerically and experimentally. The advanced CFD model of two-phase flow, which calculated the 3D distributions of pressure, gas and liquid velocities and gas and liquid volume fractions, has been developed to account for all the major components in the system, and appropriate constitutive equations for two-phase flow parameters were selected for various parts of the system, such as the cell stack, riser, separator and downcomer. Heat transfer between the two phases, and between the gas-liquid mixture and cooling coils located in the gas-liquid separator was also accounted for. The model was validated using comparisons of predicted liquid flow rate with the liquid flow rate measured in the downcomer, where a single-phase liquid flow existed. The effects of pressure, current density, number of cells, and bubble size were investigated with the numerical model. The numerical predictions matched the general trends obtained from the experimental results with regard to the effects of pressure and current density on the liquid flow rate. The validated CFD model is being used as a cell design tool at Hydrogenics Corporation.

Modeling Oscillatory Behavior of Electrical Submersible Pump Wells Under Two-Phase Flow Conditions

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Rinaldo Antonio de Melo Vieira ◽  
Mauricio Gargaglione Prado
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Two Phase Flow ◽  
Liquid Flow Rate ◽  
Oscillatory Behavior ◽  
Phase Flow ◽  
Submersible Pump ◽  
Flow Conditions ◽  
Two Phase ◽  
Electrical Submersible Pump

The effect of free gas on electrical submersible pump (ESP) performance is well known. At a constant rotational speed and constant liquid flow rate, a small amount of gas causes a mild head reduction when compared to the single phase liquid head. However, at higher gas rates, a drastic reduction in the head is observed. This critical condition, known as the surging point, is a combination of liquid and gas flow rates that cause a maximum in the head performance curve. The first derivative of the head with respect to the liquid flow rate changes sign as the liquid flow rate crosses the surging point. In several works on ESP two-phase flow performance, production conditions to the left of the surging region are described or reported as unstable operational conditions. This paper reviews basic concepts on stability of dynamical systems and shows through simulation that ESP oscillatory behavior may result from two-phase flow conditions. A specific drift flux computation code was developed to simulate the dynamic behavior of ESP wells producing without packers.

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