scholarly journals COMPARISON ANALYSIS OF CORRELATIONS FOR INTERFACIAL FRICTION FACTOR APPLIED IN GAS-LIQUID ANNULAR FLOW IN VERTICAL PIPES

2017 ◽  
Vol 16 (2) ◽  
pp. 54 ◽  
Author(s):  
C. F. de Paula Jr. ◽  
L. E. M. Lima
Keyword(s):  
Experimental Data ◽  
Friction Factor ◽  
Annular Flow ◽  
Interfacial Shear Stress ◽  
Interfacial Friction ◽  
Gas Flows ◽  
Steam Generation ◽  
Definition Of ◽  
Liquid Flows ◽  
Different Characteristics

Gas-liquid flows in pipes can occur in the form of an annular pattern in which the liquid flows as a thin film at pipe wall and the gas flows as a core in pipe center. This flow pattern is often encountered at boiling and condensation processes, for example, in industries of steam generation, cooling or petroleum. In annular flow, the interfacial friction factor is one of the important closing parameters for the definition of the interfacial shear stress and consequently the pressure gradient. In the literature, several correlations are found to estimate the interfacial friction factor. The main objective of this work is to carry out a comparative analysis of some these correlations against experimental data also obtained from the literature. The features and limitations of each correlation were observed, as well as the accuracy of each in relation to experimental data. The results obtained demonstrate that correlations analyzed, present relatively satisfactory results, despite the different characteristics of the correlations, however, it is necessary to carry out more extensive analyses involving others correlations and sets of experimental data.

scholarly journals Effects of Liquid Velocity on Pressure Gradient, Slip and Interfacial Friction Factor in Annular Flow in Horizontal Pipe

2018 ◽  
Vol 3 (8) ◽  
pp. 5
Author(s):  
Uche Osokogwu
Keyword(s):  
Pressure Gradient ◽  
Friction Factor ◽  
Annular Flow ◽  
Liquid Velocity ◽  
Interfacial Friction ◽  
Gas Velocity ◽  
Horizontal Pipe ◽  
Mixture Density ◽  
Superficial Gas Velocity ◽  
Superficial Liquid Velocity

Experimental investigations on annular flow behaviour in two-phase (air/water) flow in horizontal pipe were conducted using 2-inch (0.0504m) with a total length of 28.68m closed loop system. The emphasis from the experiments were on pressure gradient, slip and interfacial friction factor in annular flow. For interfacial friction factor, the entrainment, gas quality, the droplets and slip mixture density values were obtained through the experimental results which were substituted to determine it. In all, effects of liquid velocity were felt, as increase in superficial liquid velocity, increases the interfacial friction factor and pressure gradient in annular flow in horizontal pipes. More so, increase in superficial gas velocity, reduces the interfacial friction factor. Thus, interfacial friction factor decreases with increases in superficial gas velocity, while the pressure gradient increases with increase in superficial liquid velocity. The lower the superficial liquid velocity, the higher the slip but the lower the pressure gradient. Likewise, the lower the superficial liquid velocity, the more ripple waves obtained while the higher the superficial liquid velocity, the more disturbance waves in annular flow in horizontal pipe from the experiments.

scholarly journals Interfacial Friction Factor for Counter-Current Gas-Liquid Flows in Vertical Pipes

2017 ◽  
Vol 31 (1) ◽  
pp. 37-46 ◽  
Author(s):  
Takayoshi KUSUNOKI ◽  
Yasunori YAMAMOTO ◽  
Michio MURASE ◽  
Kosuke HAYASHI ◽  
Shigeo HOSOKAWA ◽  
...  
Keyword(s):  
Friction Factor ◽  
Interfacial Friction ◽  
Liquid Flows ◽  
Counter Current

scholarly journals A Comparison of Data Reduction Methods for Average Friction Factor Calculation of Adiabatic Gas Flows in Microchannels

Micromachines ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 171 ◽  
Author(s):  
Danish Rehman ◽  
Gian Morini ◽  
Chungpyo Hong
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Numerical Analysis ◽  
Friction Factor ◽  
Data Reduction ◽  
Hydraulic Diameter ◽  
Accurate Estimation ◽  
Gas Flows ◽  
Adiabatic Wall ◽  
Loss Coefficients

In this paper, a combined numerical and experimental approach for the estimation of the average friction factor along adiabatic microchannels with compressible gas flows is presented. Pressure-drop experiments are performed for a rectangular microchannel with a hydraulic diameter of 295 μ m by varying Reynolds number up to 17,000. In parallel, the calculation of friction factor has been repeated numerically and results are compared with the experimental work. The validated numerical model was also used to gain an insight of flow physics by varying the aspect ratio and hydraulic diameter of rectangular microchannels with respect to the channel tested experimentally. This was done with an aim of verifying the role of minor loss coefficients for the estimation of the average friction factor. To have laminar, transitional, and turbulent regimes captured, numerical analysis has been performed by varying Reynolds number from 200 to 20,000. Comparison of numerically and experimentally calculated gas flow characteristics has shown that adiabatic wall treatment (Fanno flow) results in better agreement of average friction factor values with conventional theory than the isothermal treatment of gas along the microchannel. The use of a constant value for minor loss coefficients available in the literature is not recommended for microflows as they change from one assembly to the other and their accurate estimation for compressible flows requires a coupling of numerical analysis with experimental data reduction. Results presented in this work demonstrate how an adiabatic wall treatment along the length of the channel coupled with the assumption of an isentropic flow from manifold to microchannel inlet results in a self-sustained experimental data reduction method for the accurate estimation of friction factor values even in presence of significant compressibility effects. Results also demonstrate that both the assumption of perfect expansion and consequently wrong estimation of average temperature between inlet and outlet of a microchannel can be responsible for an apparent increase in experimental average friction factor in choked flow regime.

scholarly journals Upward interfacial friction factor in gas and high-viscosity liquid flows in vertical pipes

2019 ◽  
Vol 207 (9) ◽  
pp. 1234-1263 ◽  
Author(s):  
Joseph Xavier Francisco Ribeiro ◽  
Ruiquan Liao ◽  
Aliyu Musa Aliyu ◽  
Zilong Liu
Keyword(s):  
Friction Factor ◽  
High Viscosity ◽  
Interfacial Friction ◽  
Liquid Flows

Interfacial Friction Factor Prediction in Vertical Annular Flow Based on the Interface Roughness

2018 ◽  
Vol 41 (9) ◽  
pp. 1833-1841 ◽  
Author(s):  
Baojiang Sun ◽  
Zhennan Zhang ◽  
Zhiyuan Wang ◽  
Hua Xiang
Keyword(s):  
Friction Factor ◽  
Annular Flow ◽  
Interface Roughness ◽  
Interfacial Friction

COMPARISON OF NUMERICAL SIMULATIONS WITH EXPERIMENTAL DATA FOR VERTICAL ANNULAR AND CHURN GAS-LIQUID FLOWS

2020 ◽  
Author(s):  
Larissa Steiger de Freitas ◽  
Marcus Vinícius Canhoto Alves ◽  
Rafael Rodrigues Francisco
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Liquid Flows

Simultaneous heat and mass transfer during evaporation from a film of liquid into the turbulent gas

1982 ◽  
Vol 47 (3) ◽  
pp. 766-775 ◽  
Author(s):  
Václav Kolář ◽  
Jan Červenka
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Liquid Film ◽  
Heat And Mass Transfer ◽  
Driving Forces ◽  
Proper Definition ◽  
Definition Of ◽  
Simultaneous Heat ◽  
Theory And Experiment

The paper presents results obtained by processing a series of published experimental data on heat and mass transfer during evaporation of pure liquids from the free board of a liquid film into the turbulent gas phone. The data has been processed on the basis of the earlier theory of mechanism of heat and mass transfer. In spite of the fact that this process exhibits a strong Stefan's flow, the results indicate that with a proper definition of the driving forces the agreement between theory and experiment is very good.

scholarly journals Reactivity in social scientific experiments: what is it and how is it different (and worse) than a Placebo effect?

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
María Jiménez-Buedo
Keyword(s):  
Experimental Data ◽  
Conceptual Framework ◽  
Placebo Effect ◽  
Placebo Effects ◽  
Causal Inferences ◽  
Scientific Experiments ◽  
Social Scientific ◽  
The Many ◽  
Definition Of ◽  
In Virtue Of

AbstractReactivity, or the phenomenon by which subjects tend to modify their behavior in virtue of their being studied upon, is often cited as one of the most important difficulties involved in social scientific experiments, and yet, there is to date a persistent conceptual muddle when dealing with the many dimensions of reactivity. This paper offers a conceptual framework for reactivity that draws on an interventionist approach to causality. The framework allows us to offer an unambiguous definition of reactivity and distinguishes it from placebo effects. Further, it allows us to distinguish between benign and malignant forms of the phenomenon, depending on whether reactivity constitutes a danger to the validity of the causal inferences drawn from experimental data.

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