Experimental and Numerical Investigation on the Evaporation of Shear-Driven Multicomponent Liquid Wall Films

2001 ◽  
Vol 123 (3) ◽  
pp. 580-588 ◽  
Author(s):  
M. Gerendas ◽  
S. Wittig
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Gas Turbines ◽  
Liquid Flow Rate ◽  
Liquid Films ◽  
Inlet Temperature ◽  
Two Phase ◽  
Wall Functions ◽  
Wide Range ◽  
Inlet Conditions

The presented work is concerned with two-phase flows similar to those in prefilming airblast atomizers and combustors employing film vaporization. Correlations for the multicomponent mixture properties and models for the calculations of the multicomponent evaporation were implemented in a well tested elliptic finite-volume code GAP-2D (S. Wittig et al., 1992, “Motion and Evaporation of Shear-Driven Liquid Films in Turbulent Gas,” ASME J. Eng. Gas Turbines Power 114, pp. 395–400) utilizing time-averaged quantities, k,ε turbulence model, wall functions, and curve-linear coordinates in the gas phase, adiabatic or diabatic conditions at the film plate, partially turbulent velocity profile, uniform temperature, and a rapid mixing approach in the wavy film. This new code GAP-2K was tested for stability, precision, and grid independence of the results by applying it to a turbulent hot air flow over a two-component liquid film, a mixture of water and ethanol in different concentrations. Both simulations and experiments were carried out over a wide range of inlet conditions, such as inlet pressure (1–2.6 bar), inlet temperature (298–573 K), inlet air velocity (30–120 m/s), initial liquid flow rate (0.3–1.2 cm2/s), and initial ethanol concentration (20–75 percent mass). Profiles of temperature, gas velocity, and concentration of the evaporating component normal to the film, and the development of the film temperature, the static pressure, the liquid flow rate, and the liquid compound along the film plate have been measured and compared with the simulation, showing a good match.

Experimental and Numerical Investigation on the Evaporation of Shear-Driven Multi-Component Liquid Wall Films

2000 ◽  
Author(s):  
M. Gerendas ◽  
S. Wittig
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Inlet Temperature ◽  
Two Phase ◽  
Component Mixture ◽  
Wall Functions ◽  
Hot Air ◽  
Wide Range ◽  
Inlet Conditions

The presented work is concerned with two-phase flows similar to those in prefilming airblast atomizers and combustors employing film vaporization. Correlations for the multi-component mixture properties and models for the calculations of the multi-component evaporation were implemented in a well tested elliptic finite-volume code GAP-2D (Wittig et al., 1992) utilizing time-averaged quantities, k,ε-turbulence model, wall functions, and curve-linear coordinates in the gas phase, adiabatic or diabatic conditions at the film plate, partially turbulent velocity profile, uniform temperature and rapid mixing approach in the wavy film. This new code GAP-2K was tested for stability, precision, and grid independence of the results by applying it to a turbulent hot air flow over a two-component liquid film, a mixture of water and ethanol in different concentrations. Both simulations and experiments, were carried out over a wide range of inlet conditions, such as inlet pressure (1–2.6 bar), inlet temperature (298–573 K), inlet air velocity (30–120 m/s), initial liquid flow rate (0.3–1.2 cm2/s), and initial ethanol concentration (20–75 % mass). Profiles of temperature-, gas velocity, and concentration of the evaporating component normal to the film, and the development of the film temperature, the static pressure, the liquid flow rate and the liquid compound along the film plate have been measured and compared with the simulation showing a good match.

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.

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.

Assessment of Dimensionless Correlations for Prediction of Refrigerant Mass Flow Rate Through Capillary Tubes — A Review

2017 ◽  
Vol 25 (04) ◽  
pp. 1730004 ◽  
Author(s):  
Mehdi Rasti ◽  
Ji Hwan Jeong
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Capillary Tube ◽  
Capillary Tubes ◽  
Two Phase ◽  
Comprehensive Review ◽  
Wide Range ◽  
Inlet Conditions ◽  
Dimensionless Correlations

Capillary tubes are widely used as expansion devices in small-capacity refrigeration systems. Since the refrigerant flow through the capillary tubes is complex, many researchers presented empirical dimensionless correlations to predict the refrigerant mass flow rate. A comprehensive review of the dimensionless correlations for the prediction of refrigerants mass flow rate through straight and coiled capillary tubes depending on their geometry and adiabatic or diabatic capillary tubes depending on the flow configurations has been discussed. A comprehensive review shows that most of previous dimensionless correlations have problems such as discontinuity at the saturated lines or ability to predict the refrigerant mass flow rate only for the capillary tube subcooled inlet condition. The correlations suggested by Rasti et al. and Rasti and Jeong appeared to be general and continuous and these correlations can be used to predict the refrigerant mass flow rate through all the types of capillary tubes with wide range of capillary tube inlet conditions including subcooled liquid, two-phase mixture, and superheated vapor conditions.

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.

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.

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