Mass Transfer in Single Bends Under Annular Two Phase Flow Conditions

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
H. Mazhar ◽  
D. Ewing ◽  
J. S. Cotton ◽  
C. Y. Ching
Keyword(s):  
Mass Transfer ◽  
Mass Transfer Rate ◽  
Local Maximum ◽  
Outer Wall ◽  
Water Velocity ◽  
Maximum Mass ◽  
Flow Conditions ◽  
Air Velocity ◽  
Two Phase ◽  
Transfer Rates

The distributions of the mass transfer coefficient in horizontal 90 deg bends were measured under a range of two phase annular flow conditions. A dissolving wall technique at a high Schmidt number (Sc = 1280) is used for the measurements. The maximum mass transfer occurred on the centerline of the bend outer wall at an angle of approximately 50 deg from the bend inlet under all tested conditions. The area of maximum mass transfer rate was found to span approximately 30 deg in the circumferential direction. A second region of enhanced mass transfer occurred on the latter part of the bend with a local maximum occurring slightly off the bend centerline in some cases. Changing the air and water superficial velocities (Jv = 22–30 m/s, JL = 0.17–0.41 m/s) showed that the air velocity had a larger effect on the mass transfer rates than the water velocity; however, the effect of the water velocity on the mass transfer was not insignificant.

Flow Accelerated Corrosion in Single Bends Under Annular Two Phase Flow Conditions

2012 ◽  
Author(s):  
H. Mazhar ◽  
D. Ewing ◽  
J. S. Cotton ◽  
C. Schefski ◽  
C. Y. Ching
Keyword(s):  
Mass Transfer ◽  
Local Maximum ◽  
Outer Wall ◽  
Water Velocity ◽  
Maximum Mass ◽  
Flow Conditions ◽  
Air Velocity ◽  
Two Phase ◽  
Accelerated Corrosion ◽  
Flow Accelerated Corrosion

The distributions of the mass transfer coefficient in horizontal 90 degree bends were measured under a range of two phase annular flow conditions. A dissolving wall technique at a high Schmidt number (Sc = 1280) is used for the measurements. The maximum mass transfer occurred on the centerline of the bend outer wall at an angle of approximately 50 degrees from the bend inlet under all tested conditions. The area of maximum mass transfer was found to span approximately 30 degrees in the circumferential direction. A second region of enhanced mass transfer occurred on the latter part of the bend with a local maximum occurring slightly off the bend centerline in some cases. Changing the air and water superficial velocities (Jν = 20 to 30 m/s, JL = 0.17 to 0.41 m/s) showed that the air velocity had a larger effect on the mass transfer than the water velocity; however the effect of the water velocity on the mass transfer was not insignificant.

scholarly journals Experimental investigation of hydrodynamic phenomena in vertical-upward adiabatic two-phase flow conditions

2021 ◽  
Vol 10 (3) ◽  
pp. 49-59
Author(s):  
Dinh Anh Tuan ◽  
Pham Tuan Nam ◽  
Nguyen Tu Oanh
Keyword(s):  
Experimental Investigation ◽  
Atmospheric Pressure ◽  
Two Phase Flow ◽  
Water Velocity ◽  
Phase Flow ◽  
Flow Conditions ◽  
Air Velocity ◽  
Two Phase ◽  
Single Flow ◽  
Flow Experiments

In order to investigate hydrodynamic phenomena in two-phase flow conditions in nuclear safety analysis, a series of two-phase flow experiments were conducted using a single flow channel in which air and water were simultaneously injected into the test section. The experiments under atmospheric pressure conditions were carried out with the water velocity and the air velocity covering the ranges from 0.2 to 1.5 m/s and 0.05 to 0.2 m/s, respectively. The technique of two-sensor conductivity probe was used for the measurement of bubble parameters. The experimental results presented and analyzed in this study are the local time-averaged void fraction and bubble velocities at three axial positions L/D = 14.4, 51.2 and 71.3.

scholarly journals ANALYSIS OF INTERFACIAL AND MASS TRANSFER EFFECTS ON FORCED CONVECTION IN GAS-LIQUID ANNULAR TWO-PHASE FLOW

2004 ◽  
Vol 3 (1) ◽  
pp. 45
Author(s):  
E. Nogueira ◽  
B. D. Dantas ◽  
R. M. Cotta
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Film Thickness ◽  
Liquid Film ◽  
Liquid Film Thickness ◽  
Phase Flow ◽  
Transfer Effects ◽  
Two Phase ◽  
Transfer Rates ◽  
Interface Waves

In a gas-liquid annular two-phase flow one of the main factors influencing the determination of heat transfer rates is the average thickness of the liquid film. A model to accurately represent the heat transfer in such situations has to be able of determining the average liquid film thickness to within a reasonable accuracy. A typical physical aspect in gas-liquid annular flows is the appearance of interface waves, which affect heat, mass and momentum transfers. Existing models implicitly consider the wave effects in the momentum transfer by an empirical correlation for the interfacial friction factor. However, this procedure does not point out the difference between interface waves and the natural turbulent effects of the system. In the present work, the wave and mass transfer effects in the theoretical estimation of average liquid film thickness are analyzed, in comparison to a model that does not explicitly include these effects, as applied to the prediction of heat transfer rates in a thermally developing flow situation.

Influence of Non-Newtonian Rheology on Mass Transfer From a Biofluid in Separated and Reattached Flows

2018 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Mass Transfer ◽  
Yield Stress ◽  
Mass Transfer Rate ◽  
Flow Region ◽  
Shear Thinning ◽  
Recirculation Region ◽  
Transfer Rates ◽  
Separated And Reattached Flow ◽  
The Impact ◽  
Wall Mass

Influence of the rheological model selection on the flow and mass transfer behavior of human blood in a separated and reattached flow region is investigated. Newtonian and non-Newtonian hemorheological models that account for the yield stress and shear-thinning characteristics of blood are used. The conservation of mass, momentum, and species equations as well as the Herschel-Bulkley constitutive equation are solved numerically using a finite-difference scheme. A parametric study is performed to reveal the impact of flow restriction and rheological modelling on blood-borne oxygen exchange with the confining walls. The wall mass transfer rates within the separated and reattached regions display a strong dependency on the used hemorheological model. Newtonian and non-Newtonian models result in a peak wall mass transfer rate within the recirculation region. However, non-Newtonian models that account for the yield stress and shear-thinning effects predict a substantial, highly localized, drop in the wall mass transfer rates of oxygen, at the reattachment point.

scholarly journals Analysis of Heat and Mass Transfer for Second-Order Slip Flow on a Thin Needle Using a Two-Phase Nanofluid Model

Symmetry ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1176
Author(s):  
Siti Nur Alwani Salleh ◽  
Norfifah Bachok ◽  
Fadzilah Md Ali ◽  
Norihan Md Arifin
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Slip Flow ◽  
Second Order ◽  
Two Phase ◽  
Specific Domain ◽  
Transfer Rates ◽  
Similarity Transformations ◽  
The Stability ◽  
Good Agreement

The present paper concentrates on the second-order slip flow over a moving thin needle in a nanofluid. The combined effects of thermophoresis and Brownian motion are considered to describe the heat and mass transfer performance of nanofluid. The resulting system of equations are obtained using similarity transformations and being executed in MATLAB software via bvp4c solver. The physical characteristics of embedded parameters on velocity, temperature, concentration, coefficient of skin friction, heat and mass transfer rates are demonstrated through a graphical approach and are discussed in detail. The obtained outcomes are validated with the existing works and are found to be in good agreement. It is shown that, for a specific domain of moving parameter, dual solutions are likely to exist. The stability analysis is performed to identify the stability of the solutions gained, and it is revealed that only one of them is numerically stable. The analysis indicated that the percentage of increment in the heat and mass transfer rates from no-slip to slip condition for both thin and thick surfaces of the needle ( a = 0.1 and a = 0.2 ) are 10.77 % and 12.56 % , respectively. Moreover, the symmetric behavior is noted for the graphs of reduced heat and mass transfer when the parameters N b and N t are the same.

scholarly journals Minimum Orbital Period of Cataclysmic Variables

1979 ◽  
Vol 53 ◽  
pp. 504-504
Author(s):  
B. Paczynski ◽  
W. Krzeminski
Keyword(s):  
Mass Transfer ◽  
Angular Momentum ◽  
Orbital Period ◽  
Time Scale ◽  
Transfer Rate ◽  
Main Sequence ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Transfer Rates ◽  
Angular Momentum Loss

The shortest known orbital period of a cataclysmic binary with a hydrogen dwarf secondary filling its Roche lobe is about 80 minutes. Theoretically the shortest possible orbital period for such a system is less than 60 minutes. We tried to explain why the periods shorter than 80 minutes are not observed. We estimated the time scale of angular momentum loss of a cataclysmic binary and the resulting mass transfer rate. The minimum orbital period for a given Ṁ is obtained during the transition of the secondary from the Main Sequence onto the Degenerate Dwarf Sequence. Pmin ∝ Ṁ½ Therefore, only those systems can reach low P for which Ṁ is small. This explains why among the shortest period cataclysmic variables there are no novae: presumably their mass transfer rates are too large. It also indicates that “polars” (AM Her-type stars) and SU UMa-type stars should have low Ṁ.

Effect of Mild Sway on the Interfacial Mass Transfer Rate of Stored Liquids

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Dibakar Rakshit ◽  
K. P. Thiagarajan ◽  
R. Narayanaswamy
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Degrees Of Freedom ◽  
Mass Transfer Rate ◽  
Constant Amplitude ◽  
Two Phase ◽  
Interfacial Mass Transfer ◽  
Different Temperatures ◽  
Slow Moving ◽  
Liquid Vapor

An exploratory study of two-phase physics was undertaken in a slow moving tank containing liquid. This study is under the regime of conjugate heat and mass transfer phenomena. An experiment was designed and performed to estimate the interfacial mass transfer characteristics of a slowly moving tank. The tank was swayed at varying frequencies and constant amplitude. The experiments were conducted for a range of liquid temperatures and filling levels. The experimental setup consisted of a tank partially filled with water at different temperatures, being swayed using a six degrees-of-freedom (DOF) motion actuator. The experiments were conducted for a frequency range of 0.7–1.6 Hz with constant amplitude of 0.025 m. The evaporation of liquid from the interface and the gaseous condensation was quantified by calculating the instantaneous interfacial mass transfer rate of the slow moving tank. The dependence of interfacial mass transfer rate on the liquid–vapor interfacial temperature, the fractional concentration of the evaporating liquid, the surface area of the liquid vapor interface and the filling level of the liquid was established. As sway frequency, filling levels, and liquid temperature increased, the interfacial mass transfer rate also increased. The interfacial mass transfer rate estimated for the swaying tank compared with the interfacial mass transfer rate of stationary tank shows that vibration increases the mass transfer.

scholarly journals An Experimental Study on the Mass Transfer Rate of Droplets in Annular Two-Phase Flow

2006 ◽  
Vol 49 (2) ◽  
pp. 271-278 ◽  
Author(s):  
Tomio OKAWA ◽  
Naoya SHIMADA ◽  
Akio KOTANI ◽  
Isao KATAOKA
Keyword(s):  
Mass Transfer ◽  
Experimental Study ◽  
Transfer Rate ◽  
Two Phase Flow ◽  
Mass Transfer Rate ◽  
Phase Flow ◽  
Two Phase

scholarly journals SWSex Stars, Old Novae, and the Evolution of Cataclysmic Variables

2015 ◽  
Vol 2 (1) ◽  
pp. 188-191 ◽  
Author(s):  
L. Schmidtobreick ◽  
C. Tappert
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
High Mass ◽  
Period Range ◽  
Transfer Rates ◽  
Low Mass ◽  
Orbital Periods ◽  
Nova Outburst

The population of cataclysmic variables with orbital periods right above the period gap are dominated by systems with extremely high mass transfer rates, the so-called SW Sextantis stars. On the other hand, some old novae in this period range which are expected to show high mass transfer rate instead show photometric and/or spectroscopic resemblance to low mass transfer systems like dwarf novae. We discuss them as candidates for so-called hibernating systems, CVs that changed their mass transfer behaviour due to a previously experienced nova outburst. This paper is designed to provide input for further research and discussion as the results as such are still very preliminary.

Three-compartmental analysis of effects of D-propranolol on thyroid hormone kinetics

1988 ◽  
Vol 255 (1) ◽  
pp. E80-E86 ◽  
Author(s):  
J. T. van der Heijden ◽  
E. P. Krenning ◽  
H. van Toor ◽  
G. Hennemann ◽  
R. Docter
Keyword(s):  
Mass Transfer ◽  
Thyroid Hormone ◽  
Mass Transfer Rate ◽  
Kinetic Studies ◽  
Compartmental Analysis ◽  
Metabolic Clearance ◽  
Free T4 ◽  
Transfer Rates ◽  
Plasma Pool ◽  
Low T3

Tracer thyroxine (T4), 3.3',5-triiodothyronine (T3), and 3,3',5'-triiodothyronine (rT3) kinetic studies were performed in normal T4 substituted subjects before and during oral D-propranolol treatment to determine whether changes in thyroid hormone metabolism in a propranolol-induced low-T3 syndrome result from inhibition of 5'-deiodination or inhibition of transport of iodothyronines into tissues. Data were analyzed according to a three-compartmental model of distribution and metabolism. T4 plasma appearance rate decreased by 16% (P less than 0.01), reflecting a decreased intestinal absorption of orally administered T4 during propranolol. Serum T4 and free T4 levels increased significantly by 14%, whereas T4 metabolic clearance rate (MCR) was lowered by 26% (P less than 0.001). No changes were observed in size of the three T4 compartments or in fractional and mass transfer rates of T4 from plasma to the rapidly (REP) and slowly (SEP) equilibrating pools. Serum T3, free T3, T3 plasma pool, T3 mass transfer rate to REP and SEP, and the T3 pool masses were all significantly decreased during propranolol to a similar extent as the T3 plasma production rate (PR). T3 MCR decreased by 14% (P less than 0.05). Serum total and free rT3 increased, whereas the rT3 MCR was substantially lowered during propranolol (P less than 0.001). The rT3 plasma pool, rT3 REP and SEP, and the mass transfer rates to REP and SEP increased, whereas no alterations were observed in rT3 PR and fractional transfer rates of rT3 to REP and SEP.(ABSTRACT TRUNCATED AT 250 WORDS)

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