scholarly journals Boiling in volume of low temperature droplets of dispersed phase of liquid emulsions

2017 ◽  
Vol 21 (6 Part B) ◽  
pp. 2981-2992 ◽  
Author(s):  
Alexander Rozentsvaig ◽  
Cheslav Strashinskii
Keyword(s):  
Low Temperature ◽  
Solid Wall ◽  
Experimental Studies ◽  
Nucleate Boiling ◽  
Similarity Criteria ◽  
Dispersed Phase ◽  
Homogeneous Fluid ◽  
Liquid Systems ◽  
Physical Phenomena ◽  
Good Agreement

Mechanisms of droplets boiling in dispersed liquid-liquid systems differ significantly from more commonly studied and better understood mechanisms of vaporization in homogeneous fluids. For the analysis of boiling of liquid emulsions with low-temperature dispersed phase the theory of Labuntsov has been used, which was developed for boiling of homogeneous fluid near a solid wall. Model representations of more complex physical phenomena were substantiated using the similarity criteria, corresponding to the character of the heat exchange mechanisms with the dispersed droplets in the analogous conditions. A modified calculated dependence has been obtained for liquid emulsions with the low boiling dispersed phase. The results of the calculations are compared with the data of visual observations and experimental studies from the literature. It turned out that depending on the concentration of dis-persed phase heat transfer in emulsions is characterized by two regimes with different nucleate boiling mechanisms. Good agreement was indicated with measured data of heat flux at boiling of emulsions of water-in-oil type.

scholarly journals Dispersed phase hold-up and characteristic velocity in a pulsed packed extraction column

2012 ◽  
Vol 18 (2) ◽  
pp. 255-262 ◽  
Author(s):  
Mehdi Asadollahzadeh ◽  
Jaber Safdari ◽  
Ali Haghighi-Asl ◽  
Meisam Torab-Mostaedi
Keyword(s):  
Physical Properties ◽  
Packed Column ◽  
Operating Conditions ◽  
Empirical Correlation ◽  
Extraction Column ◽  
Dispersed Phase ◽  
Characteristic Velocity ◽  
Operating Variables ◽  
Liquid Systems ◽  
Good Agreement

Dispersed phase hold-up has been measured in a 76.2 mm diameter pulsed packed column for four different liquid-liquid systems. The effects of pulsation intensity, phase ratio, and packing characteristic on the hold-up have been investigated under a variety of operating conditions. The dispersed phase axial hold-up shows a strong non-uniformity, depending on the operating conditions. The results indicated that the characteristic velocity approach is applicable to this type of extraction column for analysis of hold-up. An empirical correlation is derived for prediction of the hold-up in terms of operating variables, physical properties of the systems, and packing geometry. Good agreement between prediction and experiments was observed for all investigated operating conditions.

Phase Inversion in Two-Phase Liquid Systems

1992 ◽  
Vol 57 (7) ◽  
pp. 1419-1423
Author(s):  
Jindřich Weiss
Keyword(s):  
Interfacial Tension ◽  
Phase Inversion ◽  
Continuous Phase ◽  
Considerable Effect ◽  
Weak Dependence ◽  
Dispersed Phase ◽  
Two Phase ◽  
Liquid Systems ◽  
Phase Liquid

New data on critical holdups of dispersed phase were measured at which the phase inversion took place. The systems studied differed in the ratio of phase viscosities and interfacial tension. A weak dependence was found of critical holdups on the impeller revolutions and on the material contactor; on the contrary, a considerable effect of viscosity was found out as far as the viscosity of continuous phase exceeded that of dispersed phase.

Experimental Studies of New GaAs Metal/Insulator/p-n+Switches Using Low Temperature Oxide

2002 ◽  
Vol 25 (3) ◽  
pp. 233-237
Author(s):  
K. F. Yarn
Keyword(s):  
Low Temperature ◽  
Negative Differential Resistance ◽  
Doping Concentration ◽  
Experimental Studies ◽  
Differential Resistance ◽  
Switching Behavior ◽  
Metal Insulator ◽  
Turn On ◽  
Temperature Oxide ◽  
Phase Chemical

First observation of switching behavior is reported in GaAs metal-insulator-p-n+structure, where the thin insulator is grown at low temperature by a liquid phase chemical-enhanced oxide (LPECO) with a thickness of 100 Å. A significant S-shaped negative differential resistance (NDR) is shown to occur that originates from the regenerative feedback in a tunnel metal/insulator/semiconductor (MIS) interface andp-n+junction. The influence of epitaxial doping concentration on the switching and holding voltages is investigated. The switching voltages are found to be decreased when increasing the epitaxial doping concentration, while the holding voltages are almost kept constant. A high turn-off/turn-on resistance ratio up to105has been obtained.

scholarly journals Experimental studies on the transformation from firn to ice in the wet-snow zone of temperate glaciers

1997 ◽  
Vol 24 ◽  
pp. 181-185 ◽  
Author(s):  
Katsuhisa Kawashima ◽  
Tomomi Yamada
Keyword(s):  
Experimental Studies ◽  
Ice Formation ◽  
Compression Tests ◽  
Densification Rate ◽  
Overburden Pressure ◽  
Proportionality Constant ◽  
Wet Snow ◽  
Water Saturated ◽  
The Relationship ◽  
Good Agreement

The densification of water-saturated firn, which had formed just above the firn-ice transition in the wet-snow zone of temperate glaciers, was investigated by compression tests under pressures ranging from 0.036 to 0.173 MPa, with special reference to the relationship between densification rate, time and pressure. At each test, the logarithm of the densification rate was proportional to the logarithm of the time, and its proportionality constant increased exponentially with increasing pressure. The time necessary for ice formation in the firn aquifer was calculated using the empirical formula obtained from the tests. Consequently, the necessary time decreased exponentially as the pressure increased, which shows that the transformation from firn in ice can be completed within the period when the firn aquifer exists, if the overburden pressure acting on the water-saturated firn is above 0.12–0.14 MPa. This critical value of pressure was in good agreement with the overburden pressure obtained from depth–density curves of temperate glaciers. It was concluded that the depth of firn–ice transition was self-balanced by the overburden pressure to result in the concentration between 20 and 30 m.

Upward Vertical Two-Phase Flow Through an Annulus—Part II: Modeling Bubble, Slug, and Annular Flow

1992 ◽  
Vol 114 (1) ◽  
pp. 14-30 ◽  
Author(s):  
E. F. Caetano ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Physical Phenomena ◽  
Good Agreement

Mechanistic models have been developed for each of the existing two-phase flow patterns in an annulus, namely bubble flow, dispersed bubble flow, slug flow, and annular flow. These models are based on two-phase flow physical phenomena and incorporate annulus characteristics such as casing and tubing diameters and degree of eccentricity. The models also apply the new predictive means for friction factor and Taylor bubble rise velocity presented in Part I. Given a set of flow conditions, the existing flow pattern in the system can be predicted. The developed models are applied next for predicting the flow behavior, including the average volumetric liquid holdup and the average total pressure gradient for the existing flow pattern. In general, good agreement was observed between the experimental data and model predictions.

Effect of Boundary Layer Suction on Aerodynamic Performance of High-Turning Compressor Cascade

2013 ◽  
Author(s):  
Longxin Zhang ◽  
Shaowen Chen ◽  
Hao Xu ◽  
Jun Ding ◽  
Songtao Wang
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Experimental Studies ◽  
Aerodynamic Performance ◽  
Parameter Distribution ◽  
Compressor Cascade ◽  
Boundary Layer Suction ◽  
End Wall ◽  
Low Speed Wind Tunnel ◽  
Good Agreement

Compared with suction slots, suction holes are (1) flexible in distribution; (2) alterable in size; (3) easy to fabricate and (4) high in strength. In this paper, the numerical and experimental studies for a high turning compressor cascade with suction air removed by using suction holes in the end-wall at a low Mach numbers are carried out. The main objective of the investigation is to study the influence of different suction distributions on the aerodynamic performance of the compressor cascade and to find a better compound suction scheme. A numerical model was first made and validated by comparing with the experimental results. The computed flow visualization and exit parameter distribution showed a good agreement with experimental data. Second, the model was then used to simulate the influence of different suction distributions on the aerodynamic performance of the compressor cascade. A better compound suction scheme was obtained by summarizing numerical results and tested in a low speed wind tunnel. As a result, the compound suction scheme can be used to significantly improve the performance of the compressor cascade because the corner separation gets further suppressed.

Call for Nominations – The Nusselt–Reynolds Prize Sponsored by Assembly of World Conferences on Experimental Heat Transfer, Fluid Mechanics, and Thermodynamics

2000 ◽  
Vol 402 ◽  
pp. 382-382
Author(s):  
Nobuhide Kasagi
Keyword(s):  
Heat Transfer ◽  
Fluid Mechanics ◽  
Design Theory ◽  
Experimental Studies ◽  
Heat Transfer Fluid ◽  
World Conference ◽  
Experimental Heat ◽  
Technological Advances ◽  
Visualization Techniques ◽  
Physical Phenomena

The Nusselt–Reynolds Prize has been established by the Assembly of World Conferences to commemorate outstanding contributions by Wilhelm Nusselt and Osborne Reynolds as experimentalists, researchers, educators, and authors. As many as three prizes may be bestowed at every World Conference, one in each of the areas of heat transfer, fluid mechanics, thermodynamics, or any combination of these.The prize will be bestowed for outstanding scientific and engineering contributions and eminent achievements in the fields of heat transfer, fluid mechanics, and thermodynamics through (1) experimental studies and analytical/numerical extension of the measurements, (2) development of experimental techniques, visualization techniques, and/or instrumentation, and/or (3) development of design theory (that needs experimental data) and theory-based experimental correlations. These contributions should yield a deeper insight into physical phenomena involved or should yield significant technological advances. In addition to research, the awardee(s) should have made outstanding contributions to the field through teaching, design, or a combination of such activities. The prize is based on achievement through publications or through the application of the science or art. Nationality, age, sex, and society membership will not be considered when evaluating qualifications of candidates. A candidate must be living at the time of designation as a recipient of the prize.The prize consists of a bronze plaque, and engrossed certificate, and an honorarium. The prize is administered by the Prize Board. The deadline for accepting nominations for the Prize is February 2, 2000. The prize will be awarded at the Fifth World Conference during September 24–28, 2001 in Thessaloniki, Greece where the prize winners will also present plenary lectures on their subjects.Nominators can obtain further information and download the nomination form from a webpage at http://www.thtlab.t.u-tokyo.ac.jp/N-Rprize.html/.

Calculation of tunnel wall interference from wall-pressure measurements

1988 ◽  
Vol 92 (911) ◽  
pp. 36-53 ◽  
Author(s):  
P. R. Ashill ◽  
R. F. A. Keating
Keyword(s):  
Experimental Evaluation ◽  
Solid Wall ◽  
Wall Pressure ◽  
Wind Tunnels ◽  
Pressure Measurements ◽  
Complex Flows ◽  
Tunnel Wall ◽  
Model Flow ◽  
Good Agreement

Summary A method is described for calculating wall interference in solid-wall wind tunnels from measurements of static pressures at the walls. Since it does not require a simulation of the model flow, the technique is particularly suited to determining wall interference for complex flows such as those over VSTOL aircraft, helicopters and bluff shapes (e.g. cars and trucks). An experimental evaluation shows that the method gives wall-induced velocities which are in good agreement with those of existing methods in cases where these techniques are valid, and illustrates its effectiveness for inclined jets which are not readily modelled.

NMR Technique for Multiphase Fluid Study Involving Melting Phenomena

1999 ◽  
Author(s):  
Q. Ni ◽  
J. D. King ◽  
Y.-X. Tao
Keyword(s):  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Melting Rate ◽  
Analysis Method ◽  
Image Analysis Method ◽  
Equilibrium Conditions ◽  
Multiphase Fluid ◽  
Physical Phenomena ◽  
Non Destructive ◽  
Good Agreement

Abstract Nuclear magnetic resonance (NMR) sensors are used to determine the time variation of solid mass for a packed ice bed in an experiment of convective melting under non-thermal equilibrium conditions. The paper describes the basic experimental technique for NAFTM apparatus and feasibility for determining the solid volume fraction and ultimately the melting rate. The NMR technique provides an effective, non-destructive method for multiphase fluid study where phase change is one of the important physical phenomena. The results show a good agreement of data obtained by the NMR method with those from image-analysis method.

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