Countercurrent gas–liquid flow in inclined and vertical ducts — I: Flow patterns, pressure drop characteristics and flooding

Zapke, Albert; Kröger, D.G.

doi:10.1016/s0301-9322(99)00097-x

Cited by 92 publications

(32 citation statements)

References 7 publications

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“…increase as the liquid velocity increases, whereas in the experiments of Zapke & Kröger (2000a) the flooding gas velocity is found to decrease with the liquid velocity (which appears to be counterintuitive). However, confidence limits-error bars were not provided for the experiments of Zapke & Kröger (2000a), and, therefore, it is not really clear how accurate are the experimental findings.…”

Section: Comparison With Experimentsmentioning

confidence: 72%

“…In order to verify the predictions of our model, we consider air and methanol as working fluids in a vertical channel that were also considered in the experiments by Zapke & Kröger (2000a) (see their figure 8). As the parameters fall in the regime where our WIBL model was shown to have a good agreement with the OS problem, we consider the WIBL model to compute the limits of absolute instability, which we believe has a close connection to flooding.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

“…gas velocities for the absolute instability boundaries monotonically figure 8). V ℓ denotes the average liquid velocity, Vg,ZK corresponds to the average flooding gas velocity in Zapke & Kröger (2000a), V g,low and Vg,up corresponds to the lower and upper limits of absolute instability, respectively, computed using our analysis.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

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Absolute and convective instabilities in counter-current gas–liquid film flows

2014

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Absolute and convective instabilities in counter-current gas-liquid film flows. Mechanics, 763, Additional Information: Journal of Fluid• This is the accepted manuscript of an article subsequently published in We consider a thin liquid film flowing down an inclined plate in the presence of a countercurrent turbulent gas. By making appropriate assumptions, Tseluiko & Kalliadasis (2011) developed low-dimensional non-local models for the liquid problem, namely a long-wave model and a weighted integral-boundary-layer model, that incorporate the effect of the turbulent gas. By utilising these models, along with the Orr-Sommerfeld problem formulated using the full governing equations for the liquid phase and associated boundary conditions, we explore the linear stability of the gas-liquid system. In addition, we devise a generalised methodology to investigate absolute and convective instabilities in the nonlocal equations describing the gas-liquid flow. We observe that at low gas flow rates, the system is convectively unstable with the localised disturbances being convected downwards. As the gas flow rate is increased, the instability becomes absolute and localised disturbances spread across the whole domain. As the gas flow rate is further increased, the system again becomes convectively unstable with the localised disturbances propagating upwards. We find that the upper limit of the absolute instability region is close to the 'flooding' point associated with the appearance of large-amplitude standing waves, as obtained in Tseluiko & Kalliadasis (2011), and our analysis can therefore be used to predict the onset of flooding. We also find that an increase in the angle of inclination of the channel requires an increased gas flow rate for the onset of absolute instability. We generally find good agreement between the results obtained using the full equations and the reduced models. Moreover, we find that the weighted integral-boundary-layer model generally provides better agreement with the results for the full equations than the longwave model. Such an analysis is important for understanding the ranges of validity of the reduced model equations. In addition, a comparison of our theoretical predictions with the experiments of Zapke & Kröger (2000a) shows a fairly good agreement. We supplement our stability analysis with time-dependent computations of the linearised weighted integral-boundary-layer model. To provide some insight into the mechanisms of instability, we perform an energy budget analysis.

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Section: Comparison With Experimentsmentioning

confidence: 72%

Section: Comparison With Experimentsmentioning

confidence: 99%

Section: Comparison With Experimentsmentioning

confidence: 99%

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Absolute and convective instabilities in counter-current gas–liquid film flows

2014

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“…Since it is very difficult to carry out experimental studies inside packed columns, numerous researchers pay attention to a single inclined plate (Ghiaasiaan et al, 1997;Johnso, 1999;Karimi and Kawaji, 2000;Nicolaiewsky, 1999;Saber and El-Genk, 2004;Takahama and Kato, 1980;Zapke and Kröger, 2000). Some qualitative and quantitative conclusions were drawn by the experimental observation and analysis.…”

Section: Introductionmentioning

confidence: 99%

CFD Study on Liquid Flow Behavior on Inclined Flat Plate Focusing on Effect of Flow Rate

Yuan

Repke

et al. 2012

Engineering Applications of Computational Fluid Mechanics

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ABSTRACT:The factors affecting the separation efficiencies of structured packed columns are multi-scale, including the macroscopic variables (eg feed rate, pressure and temperature) and the microscopic liquid flow behavior and distribution. Especially in the situation in which the second liquid phase is inevitable within distillation columns, the microscopic liquid flow behavior could lead to the uncertainty of the separation efficiencies. This work mainly focuses on the investigation of the local flow behavior of a liquid phase flowing on an inclined steel plate at different situations. On one hand, a three-dimensional CFD model based on the VOF model is developed with the commercial CFD package, FLUENT 6.3. On the other hand, the results of the experimental study are adopted to validate partially the model. Within the developed model, the influences of the liquid and gas flow rates are studied with respect to the specific wetted area, the thickness profile of film and rivulet flows as well as the average velocity of the liquid phase.

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“…Many researchers [3,11,21] have studied their transition boundaries using Froude number as the ratio of inertia forces to gravitational forces. This dimensionless parameter which is based on gas superficial velocity is defined as follows:…”

Section: Inclined Sectionmentioning

confidence: 99%

An experimental investigation on the effect of middle length and inclination angle of S-shaped channel on two-phase flow patterns

Azadi

Gheisari

Ansari

2014

Experimental Thermal and Fluid Science

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An experimental investigation is conducted to study the effect of middle length and inclination angle of an S-shaped channel on adiabatic two-phase flow patterns. To study this effect, three channel lengths of 0.25, 0.50, and 1.00 m, and four bends at the angles of 22.5˚, 45˚, A dimensionless analysis of obtained flow pattern maps is also carried out. It is shown that effect of geometry changes along S-shaped pipeline on two-phase flow pattern transitions is determined by either inclination angle or elevation difference between two horizontal lines. The explained flow mechanisms, obtained flow pattern maps and the transition lines can be used to predict the particular flow pattern that will be established for a given mass flux, inclined length and angle along pipelines.

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Countercurrent gas–liquid flow in inclined and vertical ducts — I: Flow patterns, pressure drop characteristics and flooding

Cited by 92 publications

References 7 publications

Absolute and convective instabilities in counter-current gas–liquid film flows

Absolute and convective instabilities in counter-current gas–liquid film flows

CFD Study on Liquid Flow Behavior on Inclined Flat Plate Focusing on Effect of Flow Rate

An experimental investigation on the effect of middle length and inclination angle of S-shaped channel on two-phase flow patterns

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