A Mechanistic Slug Liquid Holdup Model for Wide Ranges of Liquid Viscosity and Pipe Inclination Angle

Rupture of a subcooled liquid film flowing over an inclined plate with a 150×150 mm heater is studied for a wide range of liquid viscosity (dynamic viscosity μ = (0.91–17.2)x10−3 Pa·s) and plate inclination angle with respect to the horizon (Θ = 3–90 deg). The main governing parameters of the experiment and their respective values are: Reynolds number Re = 0.15–54, heat flux q = 0–224 W/cm2. The effect of the heat flux on the film flow leads to the formation of periodically flowing rivulets and thin film between them. As the heat flux grows the film thickness between rivulets gradually decreases, and, upon reaching a certain threshold heat flux, qidp, the film ruptures in the area between the rivulets. The threshold heat flux increases with the flow rate of liquid and with the liquid viscosity, while the plate inclination angle has little effect on qidp. Criterion Kp, which is traditionally used in the literature to predict thermocapillary film rupture, was found to poorly generalize data for high viscous liquids (ethylene glycol, and aqueous solutions of glycerol) and also data for Θ≤45 deg. The criterion Kp was modified by taking into account characteristic critical film thickness for film rupture under isothermal conditions (no heating), deduced from existing theoretical models. The modified criterion has allowed to successfully generalize data for whole ranges of μ, Re, Θ and q, studied.

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Empirical Correlations for Prediction Slug Liquid Holdup on Slug-Pseudo-Slug and Slug-Churn Transitions in Vertical and Inclined Two-Phase Flow

SPE Production & Operations ◽

10.2118/205484-pa ◽

2021 ◽

pp. 1-13

Author(s):

Ghassan H. Abdul-Majeed ◽

Abderraouf Arabi ◽

Gabriel Soto-Cortes

Keyword(s):

Two Phase Flow ◽

Liquid Velocity ◽

Superior Performance ◽

Phase Flow ◽

Liquid Viscosity ◽

Empirical Correlations ◽

Liquid Holdup ◽

Two Phase ◽

Experimental Database ◽

Transition Models

Summary Most of the existing slug (SL) to churn (CH) or SL to pseudo-slug (PS) transition models (empirical and mechanistic) account for the effect of the SL liquid holdup (HLS). For simplicity, some of these models assume a constant value of HLS in SL/CH and SL/PS flow transitions, leading to a straightforward solution. Other models correlate HLS with different flow variables, resulting in an iterative solution for predicting these transitions. Using an experimental database collected from the open literature, two empirical correlations for prediction HLS at the SL/PS and SL/CH transitions (HLST) are proposed in this study. This database is composed of 1,029 data points collected in vertical, inclined, and horizontal configurations. The first correlation is developed for medium to high liquid viscosity two-phase flow (μL > 0.01 Pa·s), whereas the second one is developed for low liquid viscosity flow (μL ≤ 0.01 Pa·s). Both correlations are shown to be a function of superficial liquid velocity (VSL), liquid viscosity (μL), and pipe inclination angle (θ). The proposed correlations in a combination with the HLS model of Abdul-Majeed and Al-Mashat (2019) have been used to predict SL/PS and SL/CH transitions, and very satisfactory results were obtained. Furthermore, the SL/CH model of Brauner and Barnea (1986) is modified by using the proposed HLST correlations, instead of using a constant value. The modification results in a significant improvement in the prediction of SL/CH and SL/PS transitions and fixes the incorrect decrease of superficial gas velocity (VSG) with increasing VSL. The modified model follows the expected increase of VSG for high VSL, shown by the published observations. The proposed combinations are compared with the existing transition models and show superior performance among all models when tested against 357 measured data from independent studies.

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A unified correlation for predicting slug liquid holdup in viscous two-phase flow for pipe inclination from horizontal to vertical

SN Applied Sciences ◽

10.1007/s42452-018-0081-0 ◽

2018 ◽

Vol 1 (1) ◽

Cited By ~ 8

Author(s):

Ghassan H. Abdul-Majeed ◽

Ali M. Al-Mashat

Keyword(s):

Two Phase Flow ◽

Phase Flow ◽

Liquid Holdup ◽

Two Phase ◽

Pipe Inclination

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Effect of Pipe Inclination on Solids Distribution in Partially Stratified Slurry Flow

Volume 5: Multiphase Flow ◽

10.1115/ajkfluids2019-5397 ◽

2019 ◽

Author(s):

Václav Matoušek ◽

Jan Krupička ◽

Jiří Konfršt ◽

Pavel Vlasák

Keyword(s):

Uniform Distribution ◽

Cross Section ◽

Inclination Angle ◽

Concentration Profile ◽

Stratified Flow ◽

Concentration Profiles ◽

Horizontal Pipe ◽

Pipe Cross Section ◽

Test Loop ◽

Pipe Inclination

Abstract Partially stratified flows like flows of sand-water slurries exhibit non-uniform distribution of solids (expressed as a vertical profile of local volumetric concentration) in a pipe cross section. The solids distribution in such flows is sensitive to pipe inclination. The more stratified the flow is the more sensitive its concentration profile is to the pipe slope. In general, the distribution tends to become more uniform (less stratified) if the inclination angle increases from zero (horizontal pipe) to positive values (ascending pipe) up to 90 degree (vertical pipe). In a pipe inclined to negative angles (descending pipe) the development is different. The flow tends to stratify more if it changes from horizontal flow to descending flow down to the angle of about −35 degree. If the angle further decreases towards −90 degree, then the flow becomes less stratified reaching uniform distribution at the vertical position. This also means that the same flow exhibits a very different degree of stratification in ascending and descending pipes inclined to the same (mild) slope say between ±10 and ±40 degree. The rather complex development of the solids distribution with the variation of the inclination of pipe is insufficiently documented experimentally and described theoretically in predictive models for a concentration profile in partially stratified flow. In order to extend the existing limited data set with experimental data for partially stratified flow of medium sand slurry, we have carried out a laboratory experiment with the slurry of narrow graded fraction of sand with the mean grain size of 0.55 mm in our test loop with an invert U-tube inclinable to arbitrary angle between 0 and 90 degree. A pipe of the loop has an internal diameter of 100 mm. Both legs of the U-tube have a measuring section over which differential pressures are measured. Radiometric devices mounted to both measuring sections sense concentration profiles across a pipe cross section. Furthermore, the discharge of slurry is measured in the test loop. In the paper, experimental results are presented for various inclination angles with a small step between 0 and ±45 degree and a development in the shape of the concentration profiles with the changing inclination angle is analyzed. For the analysis, it is critical to distinguish between suspended load and contact load in the flow as the two loads tend to react differently to the flow inclination. The measured concentration profiles and pressure drops are compared with predictions by the layered model adapted for taking the flow inclination into account.

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Effect of Inclination Pipe Angle on Oil-Water Two Phase Flow Patterns and Pressure Loss

Volume 2: Dynamics, Vibration and Control; Energy; Fluids Engineering; Micro and Nano Manufacturing ◽

10.1115/esda2014-20083 ◽

2014 ◽

Cited By ~ 2

Author(s):

S. Alireza Hojati ◽

Pedram Hanafizadeh

Keyword(s):

Water Flow ◽

Inclination Angle ◽

Pressure Loss ◽

Two Phase Flow ◽

Flow Patterns ◽

Phase Flow ◽

Two Phase ◽

Inclination Angles ◽

Oil Water ◽

Pipe Inclination

The flow patterns in two phase and multi-phase flows is a significant factor which influences many other parameters such as drag force, drag coefficient and pressure drop in pipe lines. One of the major streams in the gas and oil industries is oil-water two phase flow. The main flow patterns in oil-water flows are bubbly, slug, dual continuous, stratified and annular. In the present work flow patterns in two phase oil-water flow were investigated in a 0.5in diameter pipe with length of 2m. 3D simulation was used for this pipe and six types of mesh grid were used to investigate mesh independency of the simulation. The proposed numerical analyses were performed by a CFD package which is based both on volume of fluid (VOF) and Eulerian-Eulerian methods. The results showed that some flow patterns can be simulated better with VOF method and some other maybe in Eulerian-Eulerian method, so these two methods were compared with together for all flow patterns. The flow patterns may be a function of many parameters in flow. One of the important parameter which may affect flow patterns in pipe line is pipe inclination angle; therefore flow patterns in the different pipe inclination angles were investigated in two phase oil-water flow. The range of inclinations has been varied between −45 to +45 degree about the horizon. In the presented simulation oil is mixed with water via a circular hole at center of the pipe, the ratio of oil surface to water surface at entrance is 2/3 so water phase was considered as the main phase. Flow patterns were investigated for every angle of pipe and numerical results were compared with available experimental data for verification. Also the flow patterns simulated by numerical approaches were compared with available flow regime maps in the previous literatures. Finally, effect of pipe inclination angle and flow patterns on the pressure loss were investigated comprehensively.

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Experimental investigation on the performance of CPU coolers: Effect of heat pipe inclination angle and the use of nanofluids

Microelectronics Reliability ◽

10.1016/j.microrel.2013.06.012 ◽

2013 ◽

Vol 53 (12) ◽

pp. 1954-1961 ◽

Cited By ~ 37

Author(s):

T. Yousefi ◽

S.A. Mousavi ◽

B. Farahbakhsh ◽

M.Z. Saghir

Keyword(s):

Experimental Investigation ◽

Heat Pipe ◽

Inclination Angle ◽

Pipe Inclination

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Concentration distribution and deposition limit of medium-coarse sand-water slurry in inclined pipe

Journal of Hydrology and Hydromechanics ◽

10.2478/johh-2019-0023 ◽

2020 ◽

Vol 68 (1) ◽

pp. 83-91

Author(s):

Pavel Vlasák ◽

Václav Matoušek ◽

Zdeněk Chára ◽

Jan Krupička ◽

Jiří Konfršt ◽

...

Keyword(s):

Inclination Angle ◽

Concentration Distribution ◽

Silica Sand ◽

Narrow Particle Size Distribution ◽

Mean Velocity ◽

Horizontal Pipe ◽

Slurry Concentration ◽

Limit Velocity ◽

Water Slurry ◽

Pipe Inclination

AbstractSand-water slurry was investigated on an experimental pipe loop of inner diameter D = 100 mm with the horizontal, inclined, and vertical smooth pipe sections. A narrow particle size distribution silica sand of mean diameter 0.87 mm was used. The experimental investigation focused on the effects of pipe inclination, overall slurry concentration, and mean velocity on concentration distribution and deposition limit velocity. The measured concentration profiles showed different degrees of stratification for the positive and negative pipe inclinations. The degree of stratification depended on the pipe inclination and on overall slurry concentration and velocity. The ascending flow was less stratified than the corresponding descending flow, the difference increasing from horizontal flow up to an inclination angle of about +30°. The deposition limit velocity was sensitive to the pipe inclination, reaching higher values in the ascending than in the horizontal pipe. The maximum deposition limit value was reached for an inclination angle of about +25°, and the limit remained practically constant in value, about 1.25 times higher than that in the horizontal pipe. Conversely, in the descending pipe, the deposition limit decreased significantly with the negative slopes and tended to be zero for an inclination angle of about −30°, where no stationary bed was observed.

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