In horizontal configuration, the gas-liquid intermittent flow can be plug or slug flows. Differen... more In horizontal configuration, the gas-liquid intermittent flow can be plug or slug flows. Different works have demonstrated that the two-phase flow pattern, despite their similarity, are different. Thus, it is important to differentiate between them in order to develop more robust predictive models. The limit of the existing model to predict the plug-to-slug flows transition were demonstrated firstly. After that, eleven existing slug liquid holdup (HLS) models were used in order to test their potential utilization for predicting the plug-to-slug flows transition. Using HLS = 0.9 as the criterion to distinguish between the two regimes, the relationship between the superficial velocities of the two phases was generated. The obtained transition lines were compared with visual observations collected from several published works in order to test the predictions of each model, and for different operating conditions. It was concluded in this paper that the slug liquid holdup models can be e...
Summary The intermittent gas-liquid flow can be seen in both vertical upward and horizontal pipes... more Summary The intermittent gas-liquid flow can be seen in both vertical upward and horizontal pipes. In a vertical pipe, the gas pockets of intermittent flow can be present as cap bubbles (cap bubble flow) or Taylor bubbles (slug flow), while in a horizontal configuration, the intermittent flow can be as plug or slug flows. Extensive literature survey has shown a lack of deep understanding of the difference between the vertical upward cap bubble and horizontal plug flow regimes. This paper explains the hydrodynamic similarities between vertical cap bubble flow and horizontal plug flow regimes. Moreover, the differences between the cap bubble and slug flow in vertical pipes are explained in detail. The study was carried out using a collected database from the open literature of different flow parameters. A comparison between the behavior of the void fraction, bubble structure velocity, slippage number, slug frequency, and slug length demonstrated the similarity between cap bubble and p...
Two-phase Gas-liquid flows have many industrial uses, such as hydrocarbon transportation and ener... more Two-phase Gas-liquid flows have many industrial uses, such as hydrocarbon transportation and energy production. The knowledge and an accurate determination of the gas phase's proportion rate in the two-phase mixture known as the gas void fraction is necessary for optimal and secure sizing of the installations where this kind of flow takes place. This paper focuses on the possibility of using a cost-effective differential pressure transmitter to measure the void fraction parameter. It is obtained using a mathematical model derived from the energy balance equation and the measured pressure drop from the vertical upward gas-liquid flow. Results on flow void fraction obtained through the use of the conductance probe method, are used to validate those derived from the pressure drop that is evaluated by employing the differential pressure transmitter. The measurement accuracy of the void fraction measured using the pressure drop technique, is found to be principally affected by the fl...
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2020
An accurate two-phase flow rate measurement is essential in many applications and industries such... more An accurate two-phase flow rate measurement is essential in many applications and industries such as; oil/gas, chemical, pipeline transportation and nuclear industry. This paper presents the findings obtained from two-phase flow rate measurements using Venturi meters coupled with conductance probe sensors. The measurement system and presented methodology can be used to directly and continuously measure the mass flow rate of gas-liquid flows without any need for using a separator. Most of the available data in literature on mass flow rate using Venturis in gas-liquid two phase flows are limited/valid to a certain flow regime. However, the experimental data presented in this paper covered a wide range of flows (i.e. bubbly, slug and churn flows). Three Venturis with different diameter ratios, β = 0.40, β = 0.55 and β = 0.75 have been employed using an air-water vertical test section. The effect of the Venturi’s geometry on the flow behaviour was also evaluated. The average void fracti...
L'effet de la non uniformite thermique dans le sens transversal sur la conversion d'energ... more L'effet de la non uniformite thermique dans le sens transversal sur la conversion d'energie est l'un des aspects traites dans la thermoacoustique. Cette non uniformite est constatee experimentalement dans les dispositifs thermoacoustiques en particulier l'echangeur de chaleur et le stack. Dans ce travail, la propagation acoustique dans un fluide confine entre deux plaques planes est etudiee avec prise en compte du gradient transverse de temperature. Un modele asymptotique est developpe afin de quantifier l'effet de ce gradient transverse sur les differentes variables acoustiques. L'approche suivie est une extension de la theorie lineaire standard qui ne s'applique que dans le cas d'un gradient transverse nul de temperature. Dans ce cadre, une expression analytique du gradient critique de temperature deduite dans ce travail, montre les consequences eventuelles du gradient transverse de temperature sur le fonctionnement des machines thermoacoustiques. E...
Pressure drop has been measured for upward single- and two-phase gas–liquid flow across an orific... more Pressure drop has been measured for upward single- and two-phase gas–liquid flow across an orifice in a vertical pipe. A conductance probe provided average void fraction upstream of the orifice. Six orifices with different apertures/thickness were mounted in turn in a 34 mm diameter transparent acrylic resin pipe. Gas and liquid superficial velocities of 0–4 m/s and 0.3–0.91 m/s, respectively, were studied. For single-phase flow, pressure drop, expressed as an Euler number, was seen to be independent of Reynolds number in turbulent region. The Euler number increased with decreasing the open area ratio/orifice thickness and increasing velocity. The pressure drop was well predicted by the correlation of Idel'chik et al. (1994, Handbook of Hydraulic Resistances, 3rd ed., CRC Press, Boca, Raton, FL.), which uses a form of Euler number. The corresponding two-phase flow pressure drop depends on the flow pattern. Decreasing open area ratio/orifice thickness increased the pressure drop....
Bubble columns are widely used as gas/liquid contactor. Their Applications affect the chemical, p... more Bubble columns are widely used as gas/liquid contactor. Their Applications affect the chemical, petrochemical and organic industry. They provide several advantages during operation and maintenance such as high heat and mass transfer rates, compactness and low operating and maintenance costs. In this work, an experimental study was carried out in a bubble column with an internal diameter of 144mm for an air-water two-phase combination. In order to study the two-phase pressure drop in the bubble column three absolute pressure transdicers were used for different gas superficial velocities. Tests were run with the gas superficial velocities ranged from 0.022 to 3.5 m/s. The pressure drop analysis was conducted. It showed that for the two-phase flow the pressure drop depends on the flow configuration. The two-phase pressure drop measurement technique was used to calculate the void fraction. Examination of the pressure signal time series as well as the visual analysis made it possible to ...
Experiments are reported on an air˗water mixture flowing through an orifice in a vertical pipe. T... more Experiments are reported on an air˗water mixture flowing through an orifice in a vertical pipe. Time series of cross˗sectionally averaged void fractions have been measured at nine axial positions by using a conductance probe technique. A series of six orifices with different thicknesses and apertures were employed. The Probability Density Function, the Power Spectral Density of the time series of cross sectionally averaged void fractions and the cross-correlation of time series from adjacent probes have been obtained to determine the effect of the orifice on the flow characteristics. The diameter area ratio and the thickness of the orifice have a higher influence on bubbly than on slug and churn flows. The recovery length is about 20, 10 and 7 pipe diameter downstream the orifice for these three flow patterns respectively. Homogenization effect needs a minimum liquid superficial velocity. Its position occurs depends on the value of this velocity and on the orifice fractional open area.
In horizontal configuration, the gas-liquid intermittent flow can be plug or slug flows. Differen... more In horizontal configuration, the gas-liquid intermittent flow can be plug or slug flows. Different works have demonstrated that the two-phase flow pattern, despite their similarity, are different. Thus, it is important to differentiate between them in order to develop more robust predictive models. The limit of the existing model to predict the plug-to-slug flows transition were demonstrated firstly. After that, eleven existing slug liquid holdup (HLS) models were used in order to test their potential utilization for predicting the plug-to-slug flows transition. Using HLS = 0.9 as the criterion to distinguish between the two regimes, the relationship between the superficial velocities of the two phases was generated. The obtained transition lines were compared with visual observations collected from several published works in order to test the predictions of each model, and for different operating conditions. It was concluded in this paper that the slug liquid holdup models can be e...
Summary The intermittent gas-liquid flow can be seen in both vertical upward and horizontal pipes... more Summary The intermittent gas-liquid flow can be seen in both vertical upward and horizontal pipes. In a vertical pipe, the gas pockets of intermittent flow can be present as cap bubbles (cap bubble flow) or Taylor bubbles (slug flow), while in a horizontal configuration, the intermittent flow can be as plug or slug flows. Extensive literature survey has shown a lack of deep understanding of the difference between the vertical upward cap bubble and horizontal plug flow regimes. This paper explains the hydrodynamic similarities between vertical cap bubble flow and horizontal plug flow regimes. Moreover, the differences between the cap bubble and slug flow in vertical pipes are explained in detail. The study was carried out using a collected database from the open literature of different flow parameters. A comparison between the behavior of the void fraction, bubble structure velocity, slippage number, slug frequency, and slug length demonstrated the similarity between cap bubble and p...
Two-phase Gas-liquid flows have many industrial uses, such as hydrocarbon transportation and ener... more Two-phase Gas-liquid flows have many industrial uses, such as hydrocarbon transportation and energy production. The knowledge and an accurate determination of the gas phase's proportion rate in the two-phase mixture known as the gas void fraction is necessary for optimal and secure sizing of the installations where this kind of flow takes place. This paper focuses on the possibility of using a cost-effective differential pressure transmitter to measure the void fraction parameter. It is obtained using a mathematical model derived from the energy balance equation and the measured pressure drop from the vertical upward gas-liquid flow. Results on flow void fraction obtained through the use of the conductance probe method, are used to validate those derived from the pressure drop that is evaluated by employing the differential pressure transmitter. The measurement accuracy of the void fraction measured using the pressure drop technique, is found to be principally affected by the fl...
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2020
An accurate two-phase flow rate measurement is essential in many applications and industries such... more An accurate two-phase flow rate measurement is essential in many applications and industries such as; oil/gas, chemical, pipeline transportation and nuclear industry. This paper presents the findings obtained from two-phase flow rate measurements using Venturi meters coupled with conductance probe sensors. The measurement system and presented methodology can be used to directly and continuously measure the mass flow rate of gas-liquid flows without any need for using a separator. Most of the available data in literature on mass flow rate using Venturis in gas-liquid two phase flows are limited/valid to a certain flow regime. However, the experimental data presented in this paper covered a wide range of flows (i.e. bubbly, slug and churn flows). Three Venturis with different diameter ratios, β = 0.40, β = 0.55 and β = 0.75 have been employed using an air-water vertical test section. The effect of the Venturi’s geometry on the flow behaviour was also evaluated. The average void fracti...
L'effet de la non uniformite thermique dans le sens transversal sur la conversion d'energ... more L'effet de la non uniformite thermique dans le sens transversal sur la conversion d'energie est l'un des aspects traites dans la thermoacoustique. Cette non uniformite est constatee experimentalement dans les dispositifs thermoacoustiques en particulier l'echangeur de chaleur et le stack. Dans ce travail, la propagation acoustique dans un fluide confine entre deux plaques planes est etudiee avec prise en compte du gradient transverse de temperature. Un modele asymptotique est developpe afin de quantifier l'effet de ce gradient transverse sur les differentes variables acoustiques. L'approche suivie est une extension de la theorie lineaire standard qui ne s'applique que dans le cas d'un gradient transverse nul de temperature. Dans ce cadre, une expression analytique du gradient critique de temperature deduite dans ce travail, montre les consequences eventuelles du gradient transverse de temperature sur le fonctionnement des machines thermoacoustiques. E...
Pressure drop has been measured for upward single- and two-phase gas–liquid flow across an orific... more Pressure drop has been measured for upward single- and two-phase gas–liquid flow across an orifice in a vertical pipe. A conductance probe provided average void fraction upstream of the orifice. Six orifices with different apertures/thickness were mounted in turn in a 34 mm diameter transparent acrylic resin pipe. Gas and liquid superficial velocities of 0–4 m/s and 0.3–0.91 m/s, respectively, were studied. For single-phase flow, pressure drop, expressed as an Euler number, was seen to be independent of Reynolds number in turbulent region. The Euler number increased with decreasing the open area ratio/orifice thickness and increasing velocity. The pressure drop was well predicted by the correlation of Idel'chik et al. (1994, Handbook of Hydraulic Resistances, 3rd ed., CRC Press, Boca, Raton, FL.), which uses a form of Euler number. The corresponding two-phase flow pressure drop depends on the flow pattern. Decreasing open area ratio/orifice thickness increased the pressure drop....
Bubble columns are widely used as gas/liquid contactor. Their Applications affect the chemical, p... more Bubble columns are widely used as gas/liquid contactor. Their Applications affect the chemical, petrochemical and organic industry. They provide several advantages during operation and maintenance such as high heat and mass transfer rates, compactness and low operating and maintenance costs. In this work, an experimental study was carried out in a bubble column with an internal diameter of 144mm for an air-water two-phase combination. In order to study the two-phase pressure drop in the bubble column three absolute pressure transdicers were used for different gas superficial velocities. Tests were run with the gas superficial velocities ranged from 0.022 to 3.5 m/s. The pressure drop analysis was conducted. It showed that for the two-phase flow the pressure drop depends on the flow configuration. The two-phase pressure drop measurement technique was used to calculate the void fraction. Examination of the pressure signal time series as well as the visual analysis made it possible to ...
Experiments are reported on an air˗water mixture flowing through an orifice in a vertical pipe. T... more Experiments are reported on an air˗water mixture flowing through an orifice in a vertical pipe. Time series of cross˗sectionally averaged void fractions have been measured at nine axial positions by using a conductance probe technique. A series of six orifices with different thicknesses and apertures were employed. The Probability Density Function, the Power Spectral Density of the time series of cross sectionally averaged void fractions and the cross-correlation of time series from adjacent probes have been obtained to determine the effect of the orifice on the flow characteristics. The diameter area ratio and the thickness of the orifice have a higher influence on bubbly than on slug and churn flows. The recovery length is about 20, 10 and 7 pipe diameter downstream the orifice for these three flow patterns respectively. Homogenization effect needs a minimum liquid superficial velocity. Its position occurs depends on the value of this velocity and on the orifice fractional open area.
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