Investigation in Gas-Oil Two-Phase Flow using a Differential Pressure Transducer and Wire Mesh Sensor in Vertical Pipes

The current study is performed to identify the flow regimes of oil-gas two-phase flow experimentally in a vertical pipe has an internal diameter of 6.7 cm. It also aims to provide more details about the possibility of using Differential Pressure Transducers (DPT) for indicating flow patterns. A flow development of oil and gas has been investigated in a vertical pipe of 6 m in length and operated at atmospheric pressure. A series of experiments have been run to cover a range of inlet oil superficial velocities from 0.262 to 0.419 m/s, and inlet gas superficial velocities from 0.05 to 4.7 m/s. Wire Mesh Sensors (WMS) have been used to collect the obtained void fraction values of the flow. The Differential Pressure Transducer (DPT) is utilized to measure the pressure drop values of a one-meter along the pipe. The flow patterns are classified according to the analysis of void fractions, pressure gradients regarding time series, tomographic images, probability density functions of the void fractions, and pressure gradients. A bubbly flow is observed at low superficial velocities of gas and liquid, slug flow is observed at the lower flow rate of liquid and moderate flow rates of gas, while the churn flow pattern is recognized at the higher rates of liquid and gas. Also, the result has revealed the possibility of using Differential Pressure Transducers (DPT) to classify the gas-oil flow patterns in vertical pipes

Experimental Investigation of Two-Phase Flow Patterns in a Vertical to Horizontal Bend Pipe Using Wire-Mesh Sensor

The air-water two-phase flow plays an important role in many applications of industry fields. Usually, a 90-degree bend is used to connect pipes for changing the direction of flow which influences the two-phase flow pattern. In this paper, the effect of 90-degree bend under different ranges of gas and liquid superficial velocities on the two-phase flow patterns in the horizontal pipe located after the bend was experimentally investigated, and then results were presented and compared in a two-phase flow pattern map. Also, tomographic images and probability density functions were used to capture the cross- section void fraction and its distribution for the two-phase flow patterns. The results revealed that at low liquid and gas flow rates, a stratified-wavy flow pattern was observed as a dominant flow pattern. While the wavy-annular and semiannular flow patterns were observed at a high range of gas flow rates in the horizontal pipe. The results also showed that at the high range of liquid flow rate, bubbly, plug, slug, stratified-wavy, and wavy-annular flow patterns were observed in the horizontal pipe when the gas flow increased. The tomographic images and probability density functions gave good agreement with the experimental observations and results

CFD Simulations and Experimental Observation for Air-Water Two-phase Flow in a Vertical Pipe

Air-water two-phase flow development in a vertical pipe has been investigated through service of experiments and simulations in this research. Differential Pressure Transducers (DPTs) and Wire Mesh sensors (WMSs) are used to monitor the two-phase flow in a vertical pipe of 67 mm inlet diameter and 7000 mm length. Computational Fluid Dynamic (CFD) is used to evaluate the experiments of the air-water flow in the vertical pipe using a volume of fluid (VOF) model. The operating conditions cover a range of inlet air superficial velocities from 0.05 to 5 m/s. The inlet water superficial velocity remains constant at 0.2m/s and 0.4 m/s for all experiments. The results show that the bubbly flow is noted at low superficial velocities of gas, slug flow is observed at the moderate flow rates of gas, while the churn flow pattern is observed at high rates of gas. There is no significant effect when the Usl changed from 0.2 m/s to 0.4 m/s on the vertical flow lines. Pressure drop is recorded and compared with the CFD simulations. The CFD results are over estimation compared with the experimental pressured drop with maximum absolute error of 21% at Usl of 0.2 m/s and 25% at Usl 0.4 m/s

Flow Patterns of Oil-Gas and Pressure Gradients in Near-Horizontal Flow Pipeline: Experimental Investigation Using Differential Pressure Transducers

The current investigation aimed to identify pressure gradients and to study the fully developed flow patterns of oil-gas as a blend in a pipe of internal diameter 50 mm and 6 m length with different orientations of 0, 30, and 45-degree. The study was performed at constant values of liquid superficial velocities 0.052, 0.157, 0.262, 0.314, 0.419, and 0.524 m/s, and inlet superficial velocities of gas were ranged from 0.05 to 4.7 m/s at atmospheric pressure. Two pressure transducers located up and downstream were used to measure pressure drops inside the tested pipe. Flow patterns were derived by using the correlation between pressure gradients and time series, the Probability Density Function of differential pressures, pressure gradients with gas superficial velocities, and total pressure losses with mean void fractions. The flow patterns of oil-gas were observed as a uniform stratified flow in the pipe on a 0-degree orientation at various superficial velocities. Stratified, wavy, and slug flow patterns were observed at 30-degree orientation, whereas, bubbly, slug, and churn flow patterns were observed in the pipe of 45-degree orientation. The experiment also showed that pressure drop gradients decreased with increased void fractions, gas superficial velocities, and degree rotations of the flow lines. Finally, the validation of using pressure transducers as a technique for estimating the flow patterns of two-phase flow showed acceptable results with some kind of patterns

Two-Phase Flow Development of R134a in a Horizontal Pipe: Computational Investigation

To improve the performance of vapor compression refrigeration systems that use vertical gravitational flash tank separators, the liquid separation efficiency of the vertical gravitational flash tank separator requires to be approved. To approach this improvement, the two-phase flow development and its behavior after the expansion device need to be investigated and predicted. For thus, this paper presents a three-dimensional computational investigation of the two-phase flow development of R134a after the expansion device in a horizontal pipe. Computational Fluid Dynamic (CFD) was used to predict the two-phase development and its behavior in the horizontal pipe. ANSYS 16.2 program was used to generates the geometry of the three-dimensional horizontal pipe of 2 meters long and 25 mm inner diameter. The hexahedral mesh was generated and it is assessed to obtain the optimum mesh size and number. Eulerian-Eulerian two-phase model was used with k-epsilon turbulence model. R134a was used as a working fluid in the horizontal pipe utilizing four different inlet diameters: 12, 12.5, 25, and 50.0 mm. Mass flux and vapor quality have been changed from 288 to 447 kg/m(2) .s and from 10 to 20% respectively. Results were validated against experimental results from the literature and revealed that the separation region length is affected by the initial phase velocities, inlet vapor quality, and inlet tube diameter. An empirical correlation to predict the expansion region length is proposed as a function of Froude, Webber, and Lockhart-Martinelli numbers