On the Equilibrium of Cavitation Nuclei in Liquid-Gas Solutions

1981 ◽  
Vol 103 (3) ◽  
pp. 425-430 ◽  
Author(s):  
Y. S. Cha
Keyword(s):  
Stable Equilibrium ◽  
Thermodynamic Theory ◽  
Phase System ◽  
Saturated Liquid ◽  
Theoretical Justification ◽  
Two Phase ◽  
System Pressure ◽  
Two Component ◽  
Cavitation Nuclei ◽  
The Stability

The stability of a spherical bubble in a two-component two-phase system is examined by employing the thermodynamic theory of dilute solutions. It is shown that a bubble can remain in a state of stable equilibrium provided that the ratio of the total number of moles of the solute to the total number of moles of the solvent in the system is not extremely small and that the system pressure falls between an upper bound (dissolution limit) and a lower bound (cavitation limit). The results of the analysis provide a theoretical basis for the persistence of microbubbles in a saturated liquid-gas solution. Thus to a certain extent, the results also help to resolve the dilemma that exists in the field of cavitation due to (1) the necessity of postulating the existence of microbubbles; and (2) the lack of theoretical justification for the persistence of such bubbles in a liquid.

An Edge Dislocation in a Three-Phase Composite Cylinder Model

1991 ◽  
Vol 58 (1) ◽  
pp. 75-86 ◽  
Author(s):  
H. A. Luo ◽  
Y. Chen
Keyword(s):  
Edge Dislocation ◽  
Stable Equilibrium ◽  
Phase Model ◽  
Composite Cylinder ◽  
Two Phase ◽  
Trapping Mechanism ◽  
Three Phase ◽  
Cylinder Model ◽  
Stable Equilibrium Position ◽  
The Stability

An exact solution is given for the stress field due to an edge dislocation embedded in a three-phase composite cylinder. The force on the dislocation is then derived, from which a set of simple approximate formulae is also suggested. It is shown that, in comparison with the two-phase model adopted by Dundurs and Mura (1964), the three-phase model allows the dislocation to have a stable equilibrium position under much less stringent combinations of the material constants. As a result, the so-called trapping mechanism of dislocations is more likely to take place in the three-phase model. Also, the analysis and calculation show that in the three-phase model the orientation of Burgers vector has only limited influence on the stability of dislocation. This behavior is pronouncedly different from that predicted by the two-phase model.

scholarly journals An Experimental and Numerical Analysis on the Dynamical Behavior of a Safety Valve in the Case of Two-Phase Non-Flashing Flow

2020 ◽  
Author(s):  
Mhd Ghaith Burhani ◽  
Csaba Hős
Keyword(s):  
Mass Fraction ◽  
Dynamical Behavior ◽  
Valve Lift ◽  
Test Facility ◽  
Maximum Pressure ◽  
Two Phase ◽  
Mixture Flow ◽  
System Pressure ◽  
Wide Range ◽  
The Stability

Pressure Relief Valves (PRVs) are key elements of any hydraulic system in the process industry, especially in chemical plants or hydraulic power transmission systems. Their task is to maintain the system pressure beneath a prescribed maximum pressure and vent the excessive fluid in an emergency scenario. This paper addresses the static and dynamic behavior of a Direct Spring-Operated PRV of conical shape in the presence of two-phase non-flashing flow, that is, water-air mixture. First, experimental results on the force and discharge characteristics of such a valve in a wide range of the air-to-water mass fraction are presented. Our test facility includes a custom-designed PRV with 42.5 mm inlet pipe diameter, an inlet pressure up to 6.6 bar(g) and a maximum lift of 10 mm. Additionally, the empirical results on the static characteristics, notably fluid force on the valve disc and discharge coefficients are reported as a function of the liquid mass fraction and valve lift. In the second part of the paper, we present the development of a Matlab-based simulation tool that is capable of predicting the dynamics and stability of such a valve in the case of two-phase, non-flashing, frozen-mixture flow. Moreover, the effect of system parameters, such as spring stiffness and reservoir capacity are recorded. Finally, we also present results on the stability of the opening and closing the multi-phase flow influence on the stability of the blowdown process.

Extraction and stability of selected proteins in ionic liquid based aqueous two phase systems

2014 ◽  
Vol 16 (5) ◽  
pp. 2670-2679 ◽  
Author(s):  
Rupali K. Desai ◽  
Mathieu Streefland ◽  
Rene H. Wijffels ◽  
Michel H. M. Eppink
Keyword(s):  
Ionic Liquid ◽  
Aqueous Solutions ◽  
Phase System ◽  
Two Phase ◽  
Aqueous Two Phase System ◽  
Aqueous Two Phase Systems ◽  
Phase Systems ◽  
The Stability

This article discusses the extraction of Rubisco in an ionic liquid (IL) based aqueous two phase system and the stability of proteins in aqueous solutions of IL.

Two-Phase Vessel Blowdown of an Initially Saturated Liquid—Part 2: Analytical

1983 ◽  
Vol 105 (4) ◽  
pp. 694-699 ◽  
Author(s):  
M. N. Hutcherson ◽  
R. E. Henry ◽  
D. E. Wollersheim
Keyword(s):  
Bubble Growth ◽  
Growth Analysis ◽  
Initial Period ◽  
Saturation Pressure ◽  
Equilibrium Analysis ◽  
Analytical Models ◽  
Superheated Liquid ◽  
Saturated Liquid ◽  
Two Phase ◽  
System Pressure

Analytical models are presented to predict the internal vessel conditions during the decompression regimes of an initially saturated liquid. A subcooled blowdown analysis considers the elasticity of both the liquid and vessel. A bubble growth analysis for the intermediate period of blowdown is based on thermally dominated bubble growth from a solid surface into a superheated liquid. A dispersed analysis for the latter decompression period assumes the vapor bubbles have grown sufficiently so the liquid is uniformly distributed within the vapor phase. The sub-cooled analysis predicts the initial period of blowdown reasonably well. The bubble growth analysis predicts the rise in system pressure above that value to which it initially falls after the end of subcooled blowdown. It considers an initially “slow” depressurization rate (less than 400 MPa/s) where nucleation and bubble growth is the dominate volume producing, and thus pressure recovery, mechanism. It provides insight into why the system pressure initially drops below the saturation pressure, and it also offers an explanation for the subsequent recovery of the system pressure toward the saturation pressure. The thermodynamic equilibrium analysis provides a reasonable prediction of the latter stage of decompression. The combination of these three models predicts the overall two-phase decompression phenomenon reasonably well.

Extraction of Alkali Metal and Ammonium Dipicrylaminates into Nitrobenzene in the Presence of Some Acyclic Polyethers

1992 ◽  
Vol 57 (2) ◽  
pp. 276-288 ◽  
Author(s):  
Emanuel Makrlík ◽  
Jaroslava Hálová ◽  
Petr Vaňura
Keyword(s):  
Alkali Metal ◽  
Equilibrium Constants ◽  
Phase System ◽  
Two Phase ◽  
Nitrobenzene Phase ◽  
Chemical Equilibria ◽  
Peg 400 ◽  
Maximum Value ◽  
The Stability ◽  
Crystallographic Radius

The effect of the presence of six different acyclic polyethers (2-glym, 3-glym, 4-glym, PEG 200, PEG 300 and PEG 400), denoted by L, on the distribution of alkali metal dipicrylaminates and ammonium dipicrylaminate (MA) between the aqueous and nitrobenzene phases has been studied. The two-phase system can be quantitatively described by the following five chemical equilibria: Ma+ + Aa- + L0 ↔ MLa+ + Aa-,Ma+ + Aa- ↔ M0+ + A0-, MLA0 ↔ ML0+ + A0-, MA0 ↔ M0+ + A0-, La ↔ L0, for which the respective equilibrium constants Kex(ML+, A-), Kex(M+, A-), Kd0(MLA), Kd0(MA) and KD were determined. The values of Kex(ML+,A-) increase with the increasing crystallographic radius of the M+ ion and with the number of oxyethylene units in the molecule of the ligand, L, in the series 2-glym < 3-glym < 4-glym < PEG 200 < PEG 300 < PEG 400. In addition, it has been demonstrated that the stability of the ML0+ species in the nitrobenzene phase has a maximum value for M+ = Na+ for all the studied ligands. The presence of the polyethers is detrimental to the separation of Cs+ from the other cations, but improves the separation of Na+ from Li+. The extraction selectivities for the K+/NH4+, K+/Li+ and NH4+/Li+ pairs was not significantly affected by the presence of the ligands, except for 2-glym.

Propagation of Pressure and Density in Two-Component Two-Phase System

1973 ◽  
Vol 10 (4) ◽  
pp. 250-252
Author(s):  
Keiji MIYAZAKI ◽  
Yoichi FUJII-E ◽  
Tokuo SUITA
Keyword(s):  
Phase System ◽  
Two Phase ◽  
Two Component

Throttling Effect and Thermodynamic Characteristics of Supercritical CO2 Flowing Through Shut-Off Valve

2020 ◽  
Author(s):  
Xiaolu Guo ◽  
Peng Xu ◽  
Shuangqing Xu
Keyword(s):  
Gas Phase ◽  
Supercritical Co2 ◽  
Carbon Capture ◽  
Temperature Drop ◽  
Carbon Capture And Storage ◽  
Thermodynamic Characteristics ◽  
Large Temperature ◽  
Two Phase ◽  
System Pressure ◽  
The Stability

Abstract The supercritical flow of CO2 is widely applied in energy fields such as the carbon capture and storage technology and the Brayton cycle power generation technology. The shut-off valves are widely used in various systems of energy fields, and their use is related to the stability and safety of the system. Due to the throttling effect of supercritical CO2 flowing through the valve, the large temperature drop may cause the dry ice generation, the overpressure and the blockage, which have an important impact on the safety and stability of the whole system. At present, there are few researches on the throttling effect and thermodynamic characteristics of supercritical CO2 flowing through the shut-off valve. In this paper, the pressure and temperature changes before the valve inlet and after the valve outlet were studied, and the field of pressure, temperature and phase inside the valve were analyzed. It was found that the outlet pressure of the shut-off valve increased rapidly after the valve was opened, and the temperature decreased at the same time. With the decrease of system pressure, supercritical CO2 in front of the valve changed into gas-liquid two-phase and gas-phase successively, and CO2 after the valve changed into gas-phase, liquid-phase, gas-liquid two-phase and gas-phase successively. This study is of great significance to the stability and safe operation of energy systems.

Effect of Flow on Pressure Wave Propagation in Two-Component Two-Phase System

1973 ◽  
Vol 10 (2) ◽  
pp. 127-129 ◽  
Author(s):  
Keiji MIYAZAKI ◽  
Ichiro NAKAJIMA ◽  
Yoichi FUJII-E ◽  
Tokuo SUITA
Keyword(s):  
Wave Propagation ◽  
Pressure Wave ◽  
Phase System ◽  
Two Phase ◽  
Two Component

Preparation and Characterisation of Graphene Nanofluid: To Be Used As Coolant

2020 ◽  
Author(s):  
Senthil Kumar Velukkudi Santhanam ◽  
Dolly Austen Thomas ◽  
Mystica Augustine Michael Duke ◽  
Viswanathan Doraiswamy
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Base Fluid ◽  
Solid Phase ◽  
Nano Particles ◽  
Planar Geometry ◽  
Phase System ◽  
Transfer Coefficients ◽  
Two Phase ◽  
The Stability

Abstract In the recent years, nanofluids embarked as a new class of fluids with improved thermophysical properties such as thermal conductivity, thermal diffusivity, viscosity, and convective heat transfer coefficients thus promoting better heat transfer. Nanofluids consists of two-phase system where the nano sized solid phase (nanoparticles) is dispersed into a base fluid. Graphene is a material which has two-dimensional planar geometry with thermal conductivity of the order of 5000 W/mK. Nanoparticles in the form of thin flakes as small as 50 nm, 100 nm has been used in this study. Two step technique is the used method for preparing nanofluids. Inclusion of additives in small quantity, enhance the durability of the nano particles inside the conventional base fluids. The stability of the solid nano particles inside the conventional base fluid is increased by using surfactants. The heat transfer capacity and stability of the fluids are considered as the basic properties for investigation. The nanofluids characterization studies were drawn from the SEM, XRD and thermal conductivity results. Hot wire method was used to determine the thermal conductivity of the nanofluids. The preparation and properties of graphene based nanofluids which can be used as coolant are studied in this work.

An experimental investigation of stability and interfacial waves in co-current flow of two liquids

1965 ◽  
Vol 22 (2) ◽  
pp. 217-224 ◽  
Author(s):  
M. E. Charles ◽  
L. U. Lilleleht
Keyword(s):  
Reynolds Number ◽  
Water Layer ◽  
High Water ◽  
Water Phase ◽  
Transition To Turbulence ◽  
Phase System ◽  
Interfacial Waves ◽  
Mean Flow ◽  
Two Phase ◽  
The Stability

The stability of the co-current stratified flow of oil and water was investigated experimentally in a horizontal rectangular conduit. Laminar-turbulent transitions were determined for both phases. With the two-phase system the transition to turbulence in the water phase occurred at a higher Reynolds number in the presence of a laminar oil layer provided the input water-to-oil ratio was relatively high, while the transition in the oil phase took place at a lower Reynolds number in the presence of a turbulent water layer. The appearance of first interfacial waves coincided with the transition to turbulence of the less viscous or water phase. This suggests that in the system investigated the resonance mechanism as proposed by Phillips (1957) was responsible for the generation of these first waves. However, at relatively high water flow rates and water-to-oil ratios more pronounced waves were observed which appeared to be generated by an instability in the mean flow.

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