Pressure Drop of Horizontal Air–Water Slug Flow in Different Configurations of Corrugated Pipes

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Ana Luiza B. Santana ◽  
Moisés A. Marcelino Neto ◽  
Rigoberto E. M. Morales

Abstract Corrugated pipes (CP) have regularly shaped and spaced cavities on their internal walls that can induce dynamic changes in the flow, such as increased pressure drops. Offshore petroleum production pipelines are an example of an industrial application of CPs, known as flexible lines. Slug flow is the most challenging flow pattern in those lines due to its complex hydrodynamics. A number of previous studies proposed correlations to predict the two-phase flow pressure drops in smooth pipes (SPs). However, limited researches have evaluated the pressure drops associated with liquid–gas slug flow in CPs. In this work, experiments to analyze the pressure drops in horizontal air–water slug flow under different configurations of CPs were carried out. The tests were performed in three different CP internal diameters (IDs) (26, 40, and 50 mm) with different cavity widths (1.2, 1.6, and 2.0 mm). The effects of the internal diameters and the cavity widths on the pressure drops associated with slug flow were analyzed. Results demonstrated that the pressure drops increase with increasing cavity widths. The experimental data were fitted and a pressure drop correlation using the concept of multiplier factor was proposed. Comparisons between predictions and the experimental data proved to be within ±10% accuracy.

2012 ◽  
Vol 29 (2) ◽  
pp. 115 ◽  
Author(s):  
N.Z Aung ◽  
T Yuwono

Nine existing mixture viscosity models were tested for predicting a two-phase pressure drop for oil-water flow and refrigerant (R.134a) flow. The predicted data calculated by using these mixture viscosity models were compared with experimental data. Predicted data from using one group of mixture viscosity models had a good agreement with the experimental data for oil-water two-phase flow. Another group of viscosity models was preferable for gas-liquid flow, but these models gave underestimated values with an error of about 50%. A new and more reliable mixture viscosity model was proposed for use in the prediction of pressure drop in gas-liquid two-phase flow.


Author(s):  
Mehdi Mortazavi ◽  
Kazuya Tajiri

Proton exchange membrane (PEM) fuel cells produce power with water and heat as inevitable byproducts. Accumulated liquid water within gas channel blocks the reactant flow and cause pressure drop along the gas channel. It is of extreme importance to accurately predict the liquid and gas two-phase flow pressure drop in PEM fuel cell flow channels. This pressure drop can be considered as an in-situ diagnostic tool that reveals information about the amount of liquid water accumulated within the flow channels. In this paper, the two-phase flow pressure drops are measured in ex-situ PEM fuel cell parallel flow channels. The pressure drops were measured for air mass fluxes of 2.4–6.3kg/m2s and water mass fluxes of 0.0071–1.28kg/m2s. These mass fluxes correspond to 2–5.33m/s and 7.14 × 10−6 – 0.0012m/s air and water superficial velocities, respectively. The measured two-phase flow pressure drops are then compared with different two-phase flow pressure drop models. Qualitative and quantitative comparison between the experimental results and existing models is provided in this work.


2019 ◽  
Vol 17 (72) ◽  
pp. 101-109
Author(s):  
Muhsen Koli Nahi

The aim of this study is to discover the deviation of two phase flow correlations. A comparsion was made between the expermital values of two-phase flow pressure drops data were obtained experimentally by Al-Jumaily (1999) by using air-water mixture in a horizontal tube of (132 mm) nominal diameter and a test section of (32 m) long at pressure and temperature close to atmospheric and those predicted by three correlations well-used in the literature, which show that the homogeneous model was the best


2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Ammar Zeghloul ◽  
Hiba Bouyahiaoui ◽  
Abdelwahid Azzi ◽  
Abbas H. Hasan ◽  
Abdelsalam Al-sarkhi

Abstract This paper presents an experimental investigation of the pressure drop (DP) through valves in vertical upward flows. Experiments were carried out using a 1¼″ (DN 32) ball and gate valve. Five opening areas have been investigated from fully open to the nearly fully closed valve, using air with a superficial velocity of 0–3.5 m/s and water 0.05–0.91 m/s. These ranges cover single-phase and the bubbly, slug and churn two-phase flow regimes. It was found that for the single-phase flow experiments, the valve coefficient increases with the valve opening and is the same, in both valves, for the openings smaller than 40%. The single-phase pressure drop increases with the liquid flowrate and decreases with the opening area. The two-phase flow pressure drop was found considerably increased by reducing the opening area for both valves. It reaches its maximum values at 20% opening for the ball valve and 19% opening for the gate valve. It was also inferred that at fully opening condition, the two-phase flow multiplier, for both valves, has been found close to unity for most of the tested flow conditions. For 40 and 20% valve openings the two-phase multiplier decreases in the power-law with liquid holdup for the studied flow conditions. Models proposed originally for evaluating the pressure drop through an orifice in single-phase and two-phase flows were also applied and assessed in the present experimental data.


Author(s):  
Hao Peng ◽  
Xiang Ling

Rigorous two-phase flow modeling is one of the great challenges in the thermal sciences. A two-dimensional computational fluid dynamics (CFD) simulation of air-water two-phase pressure drop characteristics in micro-channels by using volume of fluid (VOF) method was carried out in this paper. The simulations were performed in a horizontal micro-channel with a diameter of 1.1 mm and a length of 200 mm. Firstly, a variety of air-water two-phase flow patterns (including bubbly, slug, slug-annular and annular flow) were simulated in order to validate the feasibility and reliability of the VOF method. Next to that, the two-phase pressure drops in micro-channel were analyzed numerically by using the same CFD method. Also the comparison of pressure drop among the numerical simulations, experimental data and the results calculated by homogeneous equilibrium model was presented. The agreement between numerical results and the existing experimental data was found to be satisfactory. Based on this good agreement, it is finally found that the numerical analysis procedure proposed in this paper can be used to achieve a better prediction for micro-channel air-water flow characteristics.


Author(s):  
Bofeng Bai ◽  
Maolong Liu ◽  
Xiaofei Lv ◽  
Wang Su ◽  
Xiao Yan ◽  
...  

An experimental study was conducted on the pressure drop of single phase and air-water two-phase flow in the bed of rectangular cross sections filled with uniform spheres densely. In the present flow-regime model, the bed was subdivided into a near-wall region and a central region. And a new empirical correlation for the prediction of single-phase flow pressure drops was proposed based on the model. The correlation can be used to predict the single phase pressure drop for both great tube-to-particle diameter ratio packed beds and small tube-to-particle diameter ratio packed beds and for the pebble beds packing with spherical particles and non spherical particles. A new empirical correlation for the prediction of two-phase flow pressure drops was proposed based on the gas phase relative permeability as a function of the gas phase saturation and the void fraction. The correlation fit well also for both experimental data points of spherical particles and non spherical particles.


Author(s):  
Licheng Sun ◽  
Kaichiro Mishima

2092 data of two-phase flow pressure drop were collected from 18 published papers of which the working fluids include R123, R134a, R22, R236ea, R245fa, R404a, R407C, R410a, R507, CO2, water and air. The hydraulic diameter ranges from 0.506 to 12mm; Relo from 10 to 37000, and Rego from 3 to 4×105. 11 correlations and models for calculating the two-phase frictional pressure drop were evaluated based upon these data. The results show that the accuracy of the Lockhart-Martinelli method, Mishima and Hibiki correlation, Zhang and Mishima correlation and Lee and Mudawar correalion in the laminar region is very close to each other, while the Muller-Steinhagen and Heck correlation is the best among the evaluated correlations in the turbulent region. A modified Chisholm correlation was proposed, which is better than all of the evaluated correlations in the turbulent region and its mean relative error is about 29%. For refrigerants only, the new correlation and Muller-Steinhagen and Heck correlation are very close to each other and give better agreement than the other evaluated correlations.


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