Pressure Drop in Horizontal Two-Phase Flow (original) (raw)
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Determination of Pressure Drop in Horizontal Pipes for Air – Water Two Phase Flow
Mathematical Modelling in Civil Engineering, 2013
The gas-liquid two-phase flow is characterized by continuous and local change of surface separation of phases and by their mutual interactions. Due to the instability of the flow, heat transfer and mass, a precise analytical approach is difficult to achieve. Despite these difficulties, efforts are underway to progress from the more frequent empirical studies to reliable analytical models. This requires an accurate research of the processes involved in the two phase flow and how they interact with one another. This paper aims to determine the pressure drop for a two-phase flow in a horizontal pipe of a heating plant. The author compares the results obtained by numerical simulation with existing results in the domain. The mixture is air-water, at an environmental temperature of 25°C.
Study the Effect of Pipe Geometry on Pressure Drop for Air-Water Two-Phase Flow
Design Engineering, 2021
This plan aims to examine the pressure drop in flattened copper passageways. The fluid mechanics part of the project is the subject of this article review (pressure drop and void fraction). The aim of this research is to examine the benefits and drawbacks of Two-phase flow in copper passageways with a low channel height. These passageways' possible benefits include decreased refrigerant charge, and five various channel structures are being looked at. The tubes that have been utilized are smooth tubes. The tubes are then compressed to heights of 9.0 mm, 8.8 mm, 6.0 mm, and 5.0 mm, in that order. This calculation is taken from the inside of the vent. The pressure drop increased as the tube's height declined, and it also increased with rising total volume flow rate or raising water flow rate with a steady total volume flow rate, according to the findings. The findings were also compared to the Lockhart-Martinelli prediction correlation, which showed a strong agreement.
Investigation of pressure drop in horizontal pipes with different diameters
International Journal of Multiphase Flow
The pressure drop has a significant importance in multiphase flow systems. In this paper, the effect of the volumetric quality and mixture velocity on pressure drop of gas-liquid flow in horizontal pipes of different diameters are investigated experimentally and numerically. The experimental facility was designed and built to measure the pressure drop in three pipes of 12.70, 19.05 and 25.40 mm. The water and air flow rates can be adjusted to control the mixture velocity and void fraction. The measurements are performed under constant water flow rate (CWF) by adding air to the water and constant total flow rate (CTF) in which the flow rates for both phases are changed to give same CTF. The drift-flux model is also used to predict the pressure drop for same cases. The present data is also compared with a number of empirical models from the literature. The results show that: i) the pressure drop increases with higher volumetric qualities for the cases of constant water flow rate but decreases for higher volumetric qualities of constant total flow rate due to the change in flow pattern. ii) The drift-flux model and homogenous model are the most suitable models for pressure drop prediction. KEYWORDS: Air-water flow, pressure drop, horizontal pipes, experimental measurement, drift-flux model Highlights: 1. The pressure drop in three horizontal pipes of 12.70, 19.05 and 25.40 mm is studied. 2. The pressure drop increases with higher volumetric qualities for the cases of constant water flow rate but decreases for higher volumetric qualities of constant total flow rate due to the change in flow pattern 3. The drift-flux model and homogenous model are the most suitable models for pressure drop prediction.
Pressure Drop and Void Fraction of Two-Phase Flow (Air-Water) in Grooved Vertical Pipes
Mekanika, 2023
Two-phase flows consisting of liquids and gases are often found in everyday life and are used on an industrial scale. In an industrial environment, this flow has many weaknesses, including pressure drop and void fraction. One strategy to reduce losses that arise is to use passive methods. The passive method used is to utilize the shape of the grooves in the channel. In this study, the flow is used to determine its effect on the pressure drop and void fraction that appears in two-phase flow. The experimental method was used for this study. The test pipe is equipped with 16 grooves, while the smooth pipe (without grooves) is used as a comparison. The test pipe is made of acrylic material. The water fluid is circulated using a centrifugal water pump with a superficial speed of 0.33-0.42 m/s. Air fluid is supplied using a compressor with superficial speeds of 0.049, 0.066, and 0.082 m/s. Measurement of pressure drop was carried out using a pressure transmitter with an Arduino data logger. The void fraction is calculated by determining the ratio of the volume fraction of water and air in the test tube. The results of the study revealed that the use of 16 grooves in the pipe can reduce the pressure drop and cavity fraction that appears when compared to smooth pipes.
Experimental study on vertical downward air-water two-phase flow in a large diameter pipe
Downward two-phase flows in large diameter pipes are important in various industrial applications, especially for the safety analysis in nuclear reactors. To address the issue that few data of downward flow in large diameter pipes is available for model evaluation, experiments of air–water downward flow in a pipe with inner diameter of 203.2 mm have been performed. Area-averaged void fraction and pressure measurement, as well as flow visualization, have been conducted at several axial locations. The flow conditions for superficial gas velocity range from 0.05 m/s to 3.00 m/s and for superficial liquid velocity range from 0.1 m/s to 1.5 m/s, which cover cap-bubbly flow, churn-turbulent flow and annular/falling film flow. The flow structure at several axial locations and the transition from churn-turbulent flow to annular/falling film flow have been discussed. Current available drift-flux models developed for downward flow in regular pipes as well as for upward flow in large pipes are evaluated using newly collected data. For churn-turbulent flow, the data indicates a larger drift velocity than the model prediction. Corresponding drift-flux constitutive equations are suggested which can reduce the prediction error from 34.37% to 11.79%.
Two-Phase Flow Pressure Drop Modelling in Horizontal Pipes with Different Diameters
Social Science Research Network, 2022
The two-phase frictional pressure drop has a dominant effect in many industrial applications associated with the multiphase flow. This study investigated the accuracy of several available methods for predicting two-phase frictional pressure drop of different pipe diameters using 4124 experimental data points. It is observed that the performance of the existing methods is poor in a wide range of operating conditions. Then, several Artificial Neural Network models were proposed, including six multilayer perceptron (MLP) and one Radial Basis Function (RBF) using the same data sets. The weights and biases of the ANNs were optimized using Levenberg-Marquardt (LM), Bayesian Regularization (BR), Scaled Conjugate Gradient (SCG), Resilient Backpropagation (RB), Particle Swarm Optimization (PSO) and Genetic Algorithm (GA). Statistical error analysis indicates that neural network incorporated with the Genetic Algorithm (MLP-GA) predicts the entire data set with a Root Mean Square Error of 0.525 and an Average Absolute Relative Error percentage of 6.722. Finally, the sensitivity analysis was carried out, indicating that the mass flux (G) has the highest direct impact on the two-phase frictional pressure drop.
Frontiers and Progress in Multiphase Flow I, 2014
This chapter presents an insightful discussion on flow patterns, void fraction and phenomenon of two phase frictional pressure drop in gas-liquid two phase flow. The flow structure of different flow patterns observed in gas-liquid two phase flow at various pipe orientations are described with the aid of flow visualization. This chapter is helpful in understanding the impact of varying flow patterns, pipe diameter and pipe orientation on the void fraction and two phase pressure drop. Additionally, a brief overview of the void fraction, its dependency on the flow patterns and its influence on the hydrostatic pressure drop is presented. A brief synopsis of the two phase void fraction and frictional pressure drop correlations available in the literature is presented. The performance of these correlations is assessed against a comprehensive database for air-water and refrigerant two phase flow conditions. Based on this detailed analysis, the top performing void fraction and pressure drop correlations are identified and recommended for use for these fluid combinations in different two phase flow situations. Finally, application of the recommended correlations is presented in the form of solved problems. It is expected that these solved problems will give readers an idea of selection and implementation of appropriate correlations for different two phase flow conditions.
Archives of Thermodynamics, 2012
An experimental study was conducted in order to investigate two-phase flow regimes and fully developed pressure drop in a mini-size, horizontal rectangular channel. The test section was machined in the form of an impacting tee junction in an acrylic block (in order to facilitate visualization) with a rectangular cross-section of 1.87-mm height on 20-mm width on the inlet and outlet sides. Pressure drop measurement and flow regime identification were performed on all three sides of the junction. Air-water mixtures at 200 kPa (abs) and room temperature were used as the test fluids. Four flow regimes were identified visually: bubbly, plug, churn, and annular over the ranges of gas and liquid superficial velocities of 0.04 ≤ JG ≤ 10 m/s and 0.02 ≤ JL ≤ 0.7 m/s, respectively, and a flow regime map was developed. Accuracy of the pressure-measurement technique was validated with single-phase, laminar and turbulent, fully developed data. Two-phase experiments were conducted for eight differ...
Pressure drop in two-phase flow
A computer program was developed containing some of the methods for predicting pressure drop in two-phase flow. The program contains accurate methods for predicting phase behavior and physical properties and can be used to calculate pressure drops for horizontal, inclined and vertical phases. The program was used to solve test cases for many types of flow, varying the diameter, roughness, composition, overall heat transfer coefficient, angle of inclination, and length. The Lockhart-Martinelli correlation predicts the highest pressure drop while the Beggs and Brill method predicts the lowest. The American Gas Association-American Petroleum Institute method is consistent and proved to be reliable in vertical, horizontal and inclined flow. The roughness of the pipe diameter had great effect on pressure drop in two-phase flow, while the overall heat transfer coefficient had little effect.