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Chi-chuan Wang - One of the best experts on this subject based on the ideXlab platform.
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two phase Frictional Pressure drop measurements in u type wavy tubes subject to horizontal and vertical arrangements
Applied Thermal Engineering, 2008Co-Authors: Ing Youn Chen, Jane Sunn Liaw, Chi-chuan WangAbstract:Two-phase Frictional Pressure Gradient is significantly affected by the flow patterns. Though most of the U-type wavy tubes are commonly vertically installed in the air-conditioning and refrigerating systems, yet none investigations had reported the two-phase Frictional Pressure loss in vertical U-type wavy tubes. This study presents the measurements of R-134a two-phase Frictional Pressure Gradient subject to vertical and horizontal arrangements of a U-type wavy tube with inner diameter of 5.07 mm and a curvature ratio of 5. The ratio between two-phase Pressure Gradients of U-bend and straight tube is about 2.5–3.5. For the straight tube, the Frictional two-phase Pressure Gradient ratio between the vertical and horizontal arrangements is marginally higher (1.0–1.2) for annular flow pattern at x > 0.5, and is 1.0–1.4 for the U-bend in the wavy tube. The higher resistance in the vertical arrangement is due to the buoyancy force against the flow inertia. However, for x < 0.5, this ratio is gradually increased due to the difference of flow pattern. The ratio is increased to 1.8 in the straight tube. For the U-bend, the ratio is 2.1 for flow entering the upper tube and is 1.5 for flow entering the lower tube at x = 0.1 and G = 200 kg/m2 s. For the vertical wavy tube, additional effects like the flow pattern transition, liquid flow reversal, and freezing slug may cause additional Pressure drops.
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Two-phase Frictional Pressure drop measurements in U-type wavy tubes subject to horizontal and vertical arrangements
Applied Thermal Engineering, 2007Co-Authors: Ing Youn Chen, Jane Sunn Liaw, Chi-chuan WangAbstract:Two-phase Frictional Pressure Gradient is significantly affected by the flow patterns. Though most of the U-type wavy tubes are commonly vertically installed in the air-conditioning and refrigerating systems, yet none investigations had reported the two-phase Frictional Pressure loss in vertical U-type wavy tubes. This study presents the measurements of R-134a two-phase Frictional Pressure Gradient subject to vertical and horizontal arrangements of a U-type wavy tube with inner diameter of 5.07 mm and a curvature ratio of 5. The ratio between two-phase Pressure Gradients of U-bend and straight tube is about 2.5–3.5. For the straight tube, the Frictional two-phase Pressure Gradient ratio between the vertical and horizontal arrangements is marginally higher (1.0–1.2) for annular flow pattern at x > 0.5, and is 1.0–1.4 for the U-bend in the wavy tube. The higher resistance in the vertical arrangement is due to the buoyancy force against the flow inertia. However, for x
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Evaporation of R-22 in a 7-mm microfin tube
Ashrae Transactions, 1995Co-Authors: C. S. Kuo, Chi-chuan Wang, W. Y. ChengAbstract:Experimental data on evaporation in a 7-mm-diameter microfin tube are presented. The data were taken at three different evaporation temperatures (2 C, 6 C, and 10 C, respectively). The mass flux was between 100 and 300 kg/m{sup 2}{center_dot}s and the heat flux between 7 and 12.4 kW/m{sup 2}. Data were presented in the form of local heat transfer and Frictional Pressure Gradient. The effect of heat flux, mass flux, and Pressure on the heat transfer coefficient are reported in the present investigation.
Ruud Henkes - One of the best experts on this subject based on the ideXlab platform.
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the effect of surfactants on air water annular and churn flow in vertical pipes part 2 liquid holdup and Pressure Gradient dynamics
International Journal of Multiphase Flow, 2015Co-Authors: A.t. Van Nimwegen, L.m. Portela, Ruud HenkesAbstract:Abstract In this paper, we study the effect of surfactants on both the liquid holdup and the dynamics of the Pressure Gradient in annular and churn flow in vertical pipes. This effect is linked to the influence of the surfactants on the morphology of the air–water interface, which is studied in a related paper (van Nimwegen et al., 2014). The experimental results, obtained using a vertical flow loop with a 5 cm internal diameter at ambient Pressure, show three different effects of the surfactants on the measured quantities, depending on the air and water flow rates. (i) At large air flow rates, in the annular flow regime for air–water flow, the surfactants increase the Pressure Gradient; this is solely due to the increase of the Frictional Pressure Gradient, caused by the larger interfacial stress between the foamy waves overlaying the foam substrate along the wall and the gas core. (ii) At low air flow rates and low water flow rates, in the churn flow regime for air–water flow, the surfactants decrease significantly both the average Pressure Gradient and the Pressure Gradient fluctuations. While the Frictional Pressure Gradient increases, the liquid holdup decreases by more than a factor of two; the foam suppresses the flooding waves, making the flow much more regular, leading to the small Pressure Gradient fluctuations. Furthermore, there exists an optimum surfactant concentration for decreasing the average Pressure Gradient and the Pressure Gradient fluctuations. (iii) At low air and high water flow rates, in the churn flow regime for air–water flow, the average Pressure Gradient and the Pressure Gradient fluctuations are both somewhat decreased by the surfactants.
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The effect of surfactants on air–water annular and churn flow in vertical pipes. Part 2: Liquid holdup and Pressure Gradient dynamics
International Journal of Multiphase Flow, 2015Co-Authors: A.t. Van Nimwegen, L.m. Portela, Ruud HenkesAbstract:Abstract In this paper, we study the effect of surfactants on both the liquid holdup and the dynamics of the Pressure Gradient in annular and churn flow in vertical pipes. This effect is linked to the influence of the surfactants on the morphology of the air–water interface, which is studied in a related paper (van Nimwegen et al., 2014). The experimental results, obtained using a vertical flow loop with a 5 cm internal diameter at ambient Pressure, show three different effects of the surfactants on the measured quantities, depending on the air and water flow rates. (i) At large air flow rates, in the annular flow regime for air–water flow, the surfactants increase the Pressure Gradient; this is solely due to the increase of the Frictional Pressure Gradient, caused by the larger interfacial stress between the foamy waves overlaying the foam substrate along the wall and the gas core. (ii) At low air flow rates and low water flow rates, in the churn flow regime for air–water flow, the surfactants decrease significantly both the average Pressure Gradient and the Pressure Gradient fluctuations. While the Frictional Pressure Gradient increases, the liquid holdup decreases by more than a factor of two; the foam suppresses the flooding waves, making the flow much more regular, leading to the small Pressure Gradient fluctuations. Furthermore, there exists an optimum surfactant concentration for decreasing the average Pressure Gradient and the Pressure Gradient fluctuations. (iii) At low air and high water flow rates, in the churn flow regime for air–water flow, the average Pressure Gradient and the Pressure Gradient fluctuations are both somewhat decreased by the surfactants.
Yuri S. Muzychka - One of the best experts on this subject based on the ideXlab platform.
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Modeling of Two-Phase Frictional Pressure Gradient in Circular Pipes
Volume 10: Petroleum Technology, 2015Co-Authors: M M Awad, Yuri S. MuzychkaAbstract:In this article, three different methods for modeling of twophase Frictional Pressure Gradient in circular pipes are presented. They are effective property models for homogeneous two-phase flows, an asymptotic modeling approach for separated two-phase flow, and bounds on two-phase Frictional Pressure Gradient. In the first method, new definitions for two-phase viscosity are proposed using a one-dimensional transport analogy between thermal conductivity of porous media and viscosity in two-phase flow. These new definitions can be used to compute the two-phase Frictional Pressure Gradient using the homogeneous modeling approach. In the second method, a simple semi-theoretical method for calculating two-phase Frictional Pressure Gradient using asymptotic analysis is presented. Two-phase Frictional Pressure Gradient is expressed in terms of the asymptotic single-phase Frictional Pressure Gradients for liquid and gas flowing alone. In the final method, simple rules are developed for obtaining rational bounds for two-phase Frictional Pressure Gradient in circular pipes. In all cases, the proposed modeling approaches are validated using the published experimental data.Copyright © 2015 by ASME
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Bounds on Two-Phase Frictional Pressure Gradient and Void Fraction in Circular Pipes
Advances in Mechanical Engineering, 2014Co-Authors: M M Awad, Yuri S. MuzychkaAbstract:Simple rules are developed for obtaining rational bounds for two-phase Frictional Pressure Gradient and void fraction in circular pipes. The bounds are based on turbulent-turbulent flow assumption. Both the lower and upper bounds for Frictional Pressure Gradient are based on the separate cylinders formulation. For Frictional Pressure Gradient, the lower bound is based on the separate cylinders formulation that uses the Blasius equation to represent the Fanning friction factor while the upper bound is based on the separate cylinders equation that represents well the Lockhart-Martinelli correlation for turbulent-turbulent flow. For void fraction, the lower bound is based on the separate cylinders formulation that uses the Blasius equation to predict the Fanning friction factor while the upper bound is based on the Butterworth relationship that represents well the Lockhart-Martinelli correlation. These two bounds are reversed in the case of liquid fraction (1-α). For Frictional Pressure Gradient, the model is verified using published experimental data of two-phase Frictional Pressure Gradient versus mass flux at constant mass quality. The published data include different working fluids such as R-12, R-22, and Argon at different mass qualities, different pipe diameters, and different saturation temperatures. The bounds models are also presented in a dimensionless form as two-phase Frictional multiplier (ϕ l and ϕ g) versus Lockhart-Martinelli parameter ( X) for different working fluids such as R-12, R-22, and air-water and steam mixtures. For void fraction, the bounds models are verified using published experimental data of void fraction versus mass quality at constant mass flow rate. The published data include different working fluids such as steam, R-12, R-22, and R-410A at different pipe diameters, different Pressures, and different mass flow rates. It is shown that the published data can be well bounded for a wide range of mass fluxes, mass qualities, pipe diameters, and saturation temperatures.
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Bounds on Two-Phase Frictional Pressure Gradient and Void Fraction in Circular Pipes
Advances in Mechanical Engineering, 2014Co-Authors: M M Awad, Yuri S. MuzychkaAbstract:Simple rules are developed for obtaining rational bounds for two-phase Frictional Pressure Gradient and void fraction in circular pipes. The bounds are based on turbulent-turbulent flow assumption....
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Modeling of Interfacial Component for Two-Phase Frictional Pressure Gradient at Microscales
Advances in Mechanical Engineering, 2014Co-Authors: M M Awad, Yuri S. MuzychkaAbstract:A simple approach for calculating the interfacial component of Frictional Pressure Gradient in two-phase flow at microscales is presented. This approach is developed using superposition of three Pressure Gradients: single-phase liquid, single-phase gas, and interfacial Pressure Gradient. The proposed model can be transformed in two different ways: first, two-phase interfacial multiplier for liquid flowing alone (ϕl,i2) as a function of two-phase Frictional multiplier for liquid flowing alone (ϕl2) and the Lockhart-Martinelli parameter, X, and, second, two-phase interfacial multiplier for gas flowing alone (ϕg,i2) as a function of two-phase Frictional multiplier for gas flowing alone (ϕg2) and the Lockhart-Martinelli parameter, X. This proposed model allows for the interfacial Pressure Gradient to be easily modeled. Comparisons of the proposed model with experimental data for microchannels and minichannels and existing correlations for both ϕl and ϕg versus X are presented.
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A Robust Asymptotically Based Modeling Approach for Two-Phase Flows
Advances in Mechanical Engineering, 2014Co-Authors: M M Awad, Yuri S. MuzychkaAbstract:A simple semitheoretical method for calculating two-phase Frictional Pressure Gradient in horizontal circular pipes using asymptotic analysis to develop a robust compact model is presented. Two-pha...
Ing Youn Chen - One of the best experts on this subject based on the ideXlab platform.
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two phase Frictional Pressure drop measurements in u type wavy tubes subject to horizontal and vertical arrangements
Applied Thermal Engineering, 2008Co-Authors: Ing Youn Chen, Jane Sunn Liaw, Chi-chuan WangAbstract:Two-phase Frictional Pressure Gradient is significantly affected by the flow patterns. Though most of the U-type wavy tubes are commonly vertically installed in the air-conditioning and refrigerating systems, yet none investigations had reported the two-phase Frictional Pressure loss in vertical U-type wavy tubes. This study presents the measurements of R-134a two-phase Frictional Pressure Gradient subject to vertical and horizontal arrangements of a U-type wavy tube with inner diameter of 5.07 mm and a curvature ratio of 5. The ratio between two-phase Pressure Gradients of U-bend and straight tube is about 2.5–3.5. For the straight tube, the Frictional two-phase Pressure Gradient ratio between the vertical and horizontal arrangements is marginally higher (1.0–1.2) for annular flow pattern at x > 0.5, and is 1.0–1.4 for the U-bend in the wavy tube. The higher resistance in the vertical arrangement is due to the buoyancy force against the flow inertia. However, for x < 0.5, this ratio is gradually increased due to the difference of flow pattern. The ratio is increased to 1.8 in the straight tube. For the U-bend, the ratio is 2.1 for flow entering the upper tube and is 1.5 for flow entering the lower tube at x = 0.1 and G = 200 kg/m2 s. For the vertical wavy tube, additional effects like the flow pattern transition, liquid flow reversal, and freezing slug may cause additional Pressure drops.
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Two-phase Frictional Pressure drop measurements in U-type wavy tubes subject to horizontal and vertical arrangements
Applied Thermal Engineering, 2007Co-Authors: Ing Youn Chen, Jane Sunn Liaw, Chi-chuan WangAbstract:Two-phase Frictional Pressure Gradient is significantly affected by the flow patterns. Though most of the U-type wavy tubes are commonly vertically installed in the air-conditioning and refrigerating systems, yet none investigations had reported the two-phase Frictional Pressure loss in vertical U-type wavy tubes. This study presents the measurements of R-134a two-phase Frictional Pressure Gradient subject to vertical and horizontal arrangements of a U-type wavy tube with inner diameter of 5.07 mm and a curvature ratio of 5. The ratio between two-phase Pressure Gradients of U-bend and straight tube is about 2.5–3.5. For the straight tube, the Frictional two-phase Pressure Gradient ratio between the vertical and horizontal arrangements is marginally higher (1.0–1.2) for annular flow pattern at x > 0.5, and is 1.0–1.4 for the U-bend in the wavy tube. The higher resistance in the vertical arrangement is due to the buoyancy force against the flow inertia. However, for x
M M Awad - One of the best experts on this subject based on the ideXlab platform.
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Modeling of Two-Phase Frictional Pressure Gradient in Circular Pipes
Volume 10: Petroleum Technology, 2015Co-Authors: M M Awad, Yuri S. MuzychkaAbstract:In this article, three different methods for modeling of twophase Frictional Pressure Gradient in circular pipes are presented. They are effective property models for homogeneous two-phase flows, an asymptotic modeling approach for separated two-phase flow, and bounds on two-phase Frictional Pressure Gradient. In the first method, new definitions for two-phase viscosity are proposed using a one-dimensional transport analogy between thermal conductivity of porous media and viscosity in two-phase flow. These new definitions can be used to compute the two-phase Frictional Pressure Gradient using the homogeneous modeling approach. In the second method, a simple semi-theoretical method for calculating two-phase Frictional Pressure Gradient using asymptotic analysis is presented. Two-phase Frictional Pressure Gradient is expressed in terms of the asymptotic single-phase Frictional Pressure Gradients for liquid and gas flowing alone. In the final method, simple rules are developed for obtaining rational bounds for two-phase Frictional Pressure Gradient in circular pipes. In all cases, the proposed modeling approaches are validated using the published experimental data.Copyright © 2015 by ASME
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A Note on Mixture Density Using the Shannak Definition
Journal of Nuclear Engineering and Radiation Science, 2015Co-Authors: M M AwadAbstract:In this study, a note on mixture density using the Shannak definition of the Froude number is presented (Shannak, B., 2009, “Dimensionless Numbers for Two-Phase and Multiphase Flow,” Proceedings of the International Conference on Applications and Design in Mechanical Engineering (ICADME), Penang, Malaysia, Oct. 11–13, 2009). From the definition of the two-phase Froude number, an expression of the two-phase density is obtained. The definition of the two-phase density can be used to compute the two-phase Frictional Pressure Gradient using the homogeneous modeling approach in circular pipes, minichannels, and microchannels. We cannot have gas density≤two-phase density≤liquid density for 0≤mass quality≤1. Therefore, attention must be paid when using the obtained expression of the two-phase density in this note at any x value.
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Bounds on Two-Phase Frictional Pressure Gradient and Void Fraction in Circular Pipes
Advances in Mechanical Engineering, 2014Co-Authors: M M Awad, Yuri S. MuzychkaAbstract:Simple rules are developed for obtaining rational bounds for two-phase Frictional Pressure Gradient and void fraction in circular pipes. The bounds are based on turbulent-turbulent flow assumption. Both the lower and upper bounds for Frictional Pressure Gradient are based on the separate cylinders formulation. For Frictional Pressure Gradient, the lower bound is based on the separate cylinders formulation that uses the Blasius equation to represent the Fanning friction factor while the upper bound is based on the separate cylinders equation that represents well the Lockhart-Martinelli correlation for turbulent-turbulent flow. For void fraction, the lower bound is based on the separate cylinders formulation that uses the Blasius equation to predict the Fanning friction factor while the upper bound is based on the Butterworth relationship that represents well the Lockhart-Martinelli correlation. These two bounds are reversed in the case of liquid fraction (1-α). For Frictional Pressure Gradient, the model is verified using published experimental data of two-phase Frictional Pressure Gradient versus mass flux at constant mass quality. The published data include different working fluids such as R-12, R-22, and Argon at different mass qualities, different pipe diameters, and different saturation temperatures. The bounds models are also presented in a dimensionless form as two-phase Frictional multiplier (ϕ l and ϕ g) versus Lockhart-Martinelli parameter ( X) for different working fluids such as R-12, R-22, and air-water and steam mixtures. For void fraction, the bounds models are verified using published experimental data of void fraction versus mass quality at constant mass flow rate. The published data include different working fluids such as steam, R-12, R-22, and R-410A at different pipe diameters, different Pressures, and different mass flow rates. It is shown that the published data can be well bounded for a wide range of mass fluxes, mass qualities, pipe diameters, and saturation temperatures.
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Bounds on Two-Phase Frictional Pressure Gradient and Void Fraction in Circular Pipes
Advances in Mechanical Engineering, 2014Co-Authors: M M Awad, Yuri S. MuzychkaAbstract:Simple rules are developed for obtaining rational bounds for two-phase Frictional Pressure Gradient and void fraction in circular pipes. The bounds are based on turbulent-turbulent flow assumption....
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Modeling of Interfacial Component for Two-Phase Frictional Pressure Gradient at Microscales
Advances in Mechanical Engineering, 2014Co-Authors: M M Awad, Yuri S. MuzychkaAbstract:A simple approach for calculating the interfacial component of Frictional Pressure Gradient in two-phase flow at microscales is presented. This approach is developed using superposition of three Pressure Gradients: single-phase liquid, single-phase gas, and interfacial Pressure Gradient. The proposed model can be transformed in two different ways: first, two-phase interfacial multiplier for liquid flowing alone (ϕl,i2) as a function of two-phase Frictional multiplier for liquid flowing alone (ϕl2) and the Lockhart-Martinelli parameter, X, and, second, two-phase interfacial multiplier for gas flowing alone (ϕg,i2) as a function of two-phase Frictional multiplier for gas flowing alone (ϕg2) and the Lockhart-Martinelli parameter, X. This proposed model allows for the interfacial Pressure Gradient to be easily modeled. Comparisons of the proposed model with experimental data for microchannels and minichannels and existing correlations for both ϕl and ϕg versus X are presented.
