scholarly journals Gas bubble evolution on microstructured silicon substrates

2018 ◽  
Vol 11 (12) ◽  
pp. 3452-3462 ◽  
Author(s):  
Peter van der Linde ◽  
Pablo Peñas-López ◽  
Álvaro Moreno Soto ◽  
Devaraj van der Meer ◽  
Detlef Lohse ◽  
...  
Keyword(s):  
Gas Bubbles ◽  
Chemical Processes ◽  
Silicon Substrates ◽  
Gas Bubble ◽  
Bubble Evolution

The formation, growth and detachment of gas bubbles on electrodes and gas-producing chemical processes can be controlled with novel microfabricated structures.

Mathematical Model of Gas Bubble Evolution in a Straight Tube

1999 ◽  
Vol 121 (5) ◽  
pp. 505-513 ◽  
Author(s):  
D. Halpern ◽  
Y. Jiang ◽  
J. F. Himm
Keyword(s):  
Decompression Sickness ◽  
Ambient Pressure ◽  
Fluid Motion ◽  
Gas Bubbles ◽  
Coupled System ◽  
Bubble Surface ◽  
Inert Gas ◽  
Straight Tube ◽  
Gas Bubble ◽  
Bubble Evolution

Deep sea divers suffer from decompression sickness (DCS) when their rate of ascent to the surface is too rapid. When the ambient pressure drops, inert gas bubbles may form in blood vessels and tissues. The evolution of a gas bubble in a rigid tube filled with slowly moving fluid, intended to simulate a bubble in a blood vessel, is studied by solving a coupled system of fluid-flow and gas transport equations. The governing equations for the fluid motion are solved using two techniques: an analytical method appropriate for small nondeformable spherical bubbles, and the boundary element method for deformable bubbles of arbitrary size, given an applied steady flow rate. A steady convection-diffusion equation is then solved numerically to determine the concentration of gas. The bubble volume, or equivalently the gas mass inside the bubble for a constant bubble pressure, is adjusted over time according to the mass flux at the bubble surface. Using a quasi-steady approximation, the evolution of a gas bubble in a tube is obtained. Results show that convection increases the gas pressure gradient at the bubble surface, hence increasing the rate of bubble evolution. Comparing with the result for a single gas bubble in an infinite tissue, the rate of evolution in a tube is approximately twice as fast. Surface tension is also shown to have a significant effect. These findings may have important implications for our understanding of the mechanisms of inert gas bubbles in the circulation underlying decompression sickness.

Gas bubble induced scalings in geothermal systems

2021 ◽  
Author(s):  
Lilly Zacherl ◽  
Thomas Baumann
Keyword(s):  
Ph Value ◽  
Saturation Index ◽  
Gas Bubbles ◽  
Gas Bubble ◽  
Geothermal Systems ◽  
Injection Wells ◽  
Term Operation ◽  
Maintenance Schedule ◽  
Local Experience ◽  
Maintenance Schedules

<p>Scalings in geothermal systems are affecting the efficiency and safety of geothermal systems. An operate-until-fail maintenance scheme might seem appropriate for subsurface installations where the replacement of pumps and production pipes is costly and regular maintenance comprises a complete overhaul of the installations. The situation is different for surface level installations and injection wells. Here, monitoring of the thickness of precipitates is the key to optimized maintenance schedules and long-term operation.</p><p>A questionnaire revealed that operators of geothermal facilities start with a standardized maintenance schedule which is adjusted based on local experience. Sensor networks, numerical modelling and predictive maintenance are not yet applied. In this project we are aiming to close this gap with the development of a non-invasive sensor system coupled to innovative data acquisition and evaluation and an expert system to quantitatively predict the development of precipitations in geothermal systems and open cooling towers.</p><p>Previous investigations of scalings in the lower part of production pipes of a geothermal facility suggest that the disruption of the carbonate equilibrium is triggered by the formation of gas bubbles in the pump and subsequent stripping of CO<sub>2</sub>. Although small in it's overall effect on pH-value and saturation index, significant amounts of precipitates are forming at high volumetric flow rates. To assess the kinetics of gas bubble induced precipitations laboratory experiments were run. The experiment addresses precipitations at surfaces and at the gas bubbles themselves.</p>

Nuclei and Cavitation

1970 ◽  
Vol 92 (4) ◽  
pp. 681-688 ◽  
Author(s):  
J. William Holl
Keyword(s):  
Bubble Growth ◽  
Scale Effects ◽  
Gas Bubbles ◽  
Gas Content ◽  
Gas Bubble ◽  
Cavitation Nuclei ◽  
The Stability

This paper is a review of existing knowledge on cavitation nuclei. The lack of significant tensions in ordinary liquids is due to so-called weak spots or cavitation nuclei. The various forms which have been proposed for nuclei are gas bubbles, gas in a crevice, gas bubble with organic skin, and a hydrophobic solid. The stability argument leading to the postulation of the Harvey model is reviewed. Aspects of bubble growth are considered and it is shown that bubbles having different initial sizes will undergo vaporous cavitation at different liquid tensions. The three modes of growth, namely vaporous, pseudo, and gaseous are presented and implications concerning the interpretation of data are considered. The question of the source of nuclei and implications concerning scale effects are made. The measurement of nuclei is considered together with experiments on the effect of gas content on incipient cavitation.

Behavior of Inert Gas Bubbles in Forced Convective Liquid Metal Circuits

1976 ◽  
Vol 98 (1) ◽  
pp. 5-11 ◽  
Author(s):  
W. J. Minkowycz ◽  
D. M. France ◽  
R. M. Singer
Keyword(s):  
Liquid Metal ◽  
Bubble Dynamics ◽  
Bubble Radius ◽  
Gas Bubbles ◽  
Inert Gas ◽  
Liquid Sodium ◽  
Gas Bubble ◽  
Flowing Liquid ◽  
Argon Gas ◽  
The Core

Conservation equations are derived for the motion of a small inert gas bubble in a large flowing liquid-gas solution subjected to large thermal gradients. Terms which are of the second order of magnitude under less severe and steady-state conditions are retained, thus resulting in an expanded form of the Rayleigh equation. The bubble dynamics is a function of opposing mechanisms tending to increase or decrease bubble volume while being transported with the solution. Diffusion of inert gas between the bubble and the solution is one of the most important of these mechanisms included in the analysis. The analytical model is applied to an argon gas bubble flowing in a weak solution of argon gas in liquid sodium. Calculations are performed for these fluids under conditions typical of normal and abnormal operation of a liquid metal fast breeder reactor (LMFBR) core and the resulting bubble radius, internal gas pressure, and mass of inert gas are presented in each case. An important result obtained indicates that inert gas bubbles reaching the core inlet of an LMFBR will always grow as they traverse the core under normal and extreme abnormal conditions and that the rate of growth is quite small in all cases.

scholarly journals Bubble parameters and efficiency of gas bubble evolution for a chlorine-, a hydrogen- and an oxygen-evolving wire electrode

1988 ◽  
Vol 33 (6) ◽  
pp. 769-779 ◽  
Author(s):  
J.M. Chin Kwie Joe ◽  
L.J.J. Janssen ◽  
S.J.D. van Strelen ◽  
J.H.G. Verbunt ◽  
W.M. Sluyter
Keyword(s):  
Gas Bubble ◽  
Wire Electrode ◽  
Bubble Evolution ◽  
Oxygen Evolving

On the origin of the driving force in the Marangoni propelled gas bubble trapping mechanism

2017 ◽  
Vol 19 (28) ◽  
pp. 18695-18703 ◽  
Author(s):  
A. Miniewicz ◽  
C. Quintard ◽  
H. Orlikowska ◽  
S. Bartkiewicz
Keyword(s):  
Driving Force ◽  
Gas Bubbles ◽  
Gas Bubble ◽  
Particle Trajectories ◽  
Trapping Mechanism ◽  
Bubble Trapping

Particle trajectories around gas bubbles due to Marangoni induced flows of liquid.

scholarly journals A quantitative phase-field model of gas bubble evolution in UO2

2020 ◽  
Vol 184 ◽  
pp. 109867
Author(s):  
Zhihua Xiao ◽  
Yafeng Wang ◽  
Shenyang Hu ◽  
Yulan Li ◽  
San-Qiang Shi
Keyword(s):  
Phase Field ◽  
Field Model ◽  
Phase Field Model ◽  
Gas Bubble ◽  
Quantitative Phase ◽  
Bubble Evolution

Low Level Iodine Detection by TXRF in a Reactor Safety Simulation Experiment

1986 ◽  
Vol 30 ◽  
pp. 85-88 ◽  
Author(s):  
F. Hegedüs ◽  
P. Winkler ◽  
P. Wobrauschek ◽  
Christina Streli
Keyword(s):  
Simulation Experiment ◽  
Fission Products ◽  
Gas Bubbles ◽  
Vapor Concentration ◽  
Gas Bubble ◽  
Iodine Vapor ◽  
Reactor Safety ◽  
Water Pool ◽  
Federal Institute ◽  
Water Moderator

In the event of an accident in a light water moderated nuclear plant, the fission products escape from the water moderator in form of gas bubbles. One of the most important fission products is Iodine. Presently there are only rough estimations of the escape of Iodine. The aim of the experiment planned at the Swiss Federal Institute for Reactor Research (EIR) is to simulate the conditions of an accident and to measure the amount of Iodine which escapes from the moderator water into the space inside the reactor containment.It is supposed that at 5 m depth in a water pool, the canning of the fuel element explodes releasing 1-3 liter large gas bubbles containing the volatile fission products. The Iodine vapor concentration, saturated in the gas bubble, will be about 3 mg/l. It is expected that the water strongly absorbs the Iodine vapor and the I concentration in the gas bubble arriving at the water surface will be strongly reduced to a few ug/l.

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