Formulation of a Mathematical Process Model for the Foaming of a Mesophase Carbon Precursor

1992 ◽  
Vol 270 ◽  
Author(s):  
S. S. Sandhu ◽  
J. W. Hager
Keyword(s):  
Process Model ◽  
Analytical Description ◽  
Nucleation And Growth ◽  
Bubble Surface ◽  
Bubble Nucleation ◽  
Mesophase Pitch ◽  
Experimental Production ◽  
Mathematical Equations ◽  
Experimental Effort ◽  
Mathematical Process

ABSTRACTMathematical equations have been formulated to guide an experimental effort to produce an open-celled mesophase pitch foam. The formulation provides an analytical description of homogeneous bubble nucleation and growth, diffusion of the blowing gas through the liquid to the bubble surface, and the average material thickness between bubbles. Implications of the formulation for the experimental production of mesophase pitch foam are discussed.

Dynamic observations of vesiculation reveal the role of silicate crystals in bubble nucleation and growth in andesitic magmas

Lithos ◽  
2018 ◽  
Vol 296-299 ◽  
pp. 532-546 ◽  
Author(s):  
P. Pleše ◽  
M.D. Higgins ◽  
L. Mancini ◽  
G. Lanzafame ◽  
F. Brun ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Bubble Nucleation

scholarly journals Multi-Rate Data Fusion for State and Parameter Estimation in (Bio-)Chemical Process Engineering

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1990
Author(s):  
Robert Dürr ◽  
Stefanie Duvigneau ◽  
Carsten Seidel ◽  
Achim Kienle ◽  
Andreas Bück
Keyword(s):  
Process Model ◽  
Chemical Reactor ◽  
Process Engineering ◽  
Efficient Operation ◽  
Biochemical Processes ◽  
Promising Tool ◽  
Current State ◽  
Delayed Measurement ◽  
Advanced Model ◽  
Mathematical Process

For efficient operation, modern control approaches for biochemical process engineering require information on the states of the process such as temperature, humidity or chemical composition. Those measurement are gathered from a set of sensors which differ with respect to sampling rates and measurement quality. Furthermore, for biochemical processes in particular, analysis of physical samples is necessary, e.g., to infer cellular composition resulting in delayed information. As an alternative for the use of this delayed measurement for control, so-called soft-sensor approaches can be used to fuse delayed multirate measurements with the help of a mathematical process model and provide information on the current state of the process. In this manuscript we present a complete methodology based on cascaded unscented Kalman filters for state estimation from delayed and multi-rate measurements. The approach is demonstrated for two examples, an exothermic chemical reactor and a recently developed model for biopolymer production. The results indicate that the the current state of the systems can be accurately reconstructed and therefore represent a promising tool for further application in advanced model-based control not only of the considered processes but also of related processes.

scholarly journals Plasmonic Bubble Nucleation and Growth in Water: Effect of Dissolved Air

2019 ◽  
Vol 123 (38) ◽  
pp. 23586-23593 ◽  
Author(s):  
Xiaolai Li ◽  
Yuliang Wang ◽  
Mikhail E. Zaytsev ◽  
Guillaume Lajoinie ◽  
Hai Le The ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
Water Effect ◽  
Dissolved Air

scholarly journals A complete analytical solution of the Fokker–Planck and balance equations for nucleation and growth of crystals

2018 ◽  
Vol 376 (2113) ◽  
pp. 20170327 ◽  
Author(s):  
Eugenya V. Makoveeva ◽  
Dmitri V. Alexandrov
Keyword(s):  
Distribution Function ◽  
Analytical Description ◽  
Supercooled Liquid ◽  
Intermediate Stage ◽  
Nucleation And Growth ◽  
Time Dependent ◽  
Supersaturated Solution ◽  
Nucleation Kinetics ◽  
Type Integral ◽  
Laplace Type

This article is concerned with a new analytical description of nucleation and growth of crystals in a metastable mushy layer (supercooled liquid or supersaturated solution) at the intermediate stage of phase transition. The model under consideration consisting of the non-stationary integro-differential system of governing equations for the distribution function and metastability level is analytically solved by means of the saddle-point technique for the Laplace-type integral in the case of arbitrary nucleation kinetics and time-dependent heat or mass sources in the balance equation. We demonstrate that the time-dependent distribution function approaches the stationary profile in course of time. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’.

Nucleation and Growth of Bubble With the Effects of Solute Gas

Volume 3 ◽  
2004 ◽  
Author(s):  
Shin-Ichi Tsuda ◽  
Shu Takagi ◽  
Yoichiro Matsumoto
Keyword(s):  
Saturation Pressure ◽  
Pressure Change ◽  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
Dynamics Simulation ◽  
Pure Liquid ◽  
Dissolved Gas ◽  
High Concentration ◽  
Wrong Prediction ◽  
Solvent Molecules

Bubble nucleation and growth of formed nuclei are investigated by molecular dynamics simulation in Lennard-Jones liquid with gas impurities. For the onset of nucleation from bulk, it has been found that a dissolved gas whose interaction is very weak and whose diameter is larger than that of solvent molecules makes the action to cause composition fluctuation or local phase separation so strong that the nucleation probability predicted from pressure change becomes qualitatively wrong. It has been confirmed that this wrong prediction is generally explained by introducing the superheat ratio nondimensionalized by saturation pressure and spinodal pressure. For the growth stage of formed bubble nuclei, it is observed that the coalescence of nuclei occurs when a weak-interaction gas is dissolved at a high concentration while the competition between neighbor nuclei is dominant in the case of pure liquid.

Nanosecond Imaging of Bubble Nucleation on a Microheater

2006 ◽  
Vol 128 (8) ◽  
pp. 734-734 ◽  
Author(s):  
C. Thomas Avedisian ◽  
Richard E. Cavicchi ◽  
Michael J. Tarlov
Keyword(s):  
Thin Film ◽  
Nd:Yag Laser ◽  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
Frame Rate ◽  
Vapor Film ◽  
Platinum Surface ◽  
Local Reduction ◽  
Four Corners ◽  
Collapse Phase

These images show bubble nucleation and growth of a thin film heater (a platinum film 15 μm wide, 30 μm long and 0.2 μm thick) that is heated by an 11.8 volt pulse of 0.50 μs duration in subcooled water. Imaging is by illumination from a Nd:Yag laser (hence the green colored photographs) that produces an effective frame rate of 1.3×108 frames/s (the method is described in Avedisian et al. (2006) and Balss et al. (2005)). Time is relative to the first appearance of bubbles. In the early phase, bubbles are visible at the four corners of the platinum surface (58 ns) which grow laterally into a vapor film (142 ns) that covers the surface by 178 ns after which the bubble thickens and grows into the bulk (246 ns and beyond). The collapse phase (e.g., 3.5 μs to 3.8 μs) continues well after the heater pulse is turned off. Vapor completely disappears (3.65 μs) but then bubbles reappear (3.8 μs) well after the power-off phase. Reappearance of bubbles is speculated to be the result of a stagnation-like flow induced by the rapid collapse and inward motion of liquid that jets upward to cause a local reduction of pressure to cavitate a bubble at 3.8 μs. [Avedisian, C.T., Cavicchi, R.E., Tarlov, M.J., Rev. Sci. Instruments, 2006, in press; Balss, K.M., Avedisian, C.T., Cavicchi, R.E., Tarlov, M.J., Langmuir, 21, 10459–10467 (2005)]

Modeling of helium bubble nucleation and growth in neutron irradiated boron doped RAFM steels

2012 ◽  
Vol 426 (1-3) ◽  
pp. 287-297 ◽  
Author(s):  
Christian Dethloff ◽  
Ermile Gaganidze ◽  
Vyacheslav V. Svetukhin ◽  
Jarir Aktaa
Keyword(s):  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
Helium Bubble ◽  
Boron Doped

Bubble Nucleation and Growth in Open-Cycle OTEC Subsystems

1983 ◽  
Vol 105 (2) ◽  
pp. 119-125 ◽  
Author(s):  
D. C. Bugby ◽  
A. F. Mills ◽  
A. T. Wassel
Keyword(s):  
Bubble Size ◽  
Power Plants ◽  
Distribution Systems ◽  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
Warm Water ◽  
Water Feed ◽  
Open Cycle ◽  
Ocean Thermal Energy ◽  
Available Information

Bubble nucleation and growth in the evaporator, condenser, upcomers, and feedwater distribution systems of open-cycle ocean thermal energy conversion (OTEC) power plants are examined. The phenomenon that will probably have the most impact on system design is cavitation in the warm water feed near the entrance of the evaporator. The critical bubble size for cavitation is about 105 μm. Sources of bubbles in the warm water feed are those entering from the ocean, those nucleating on suspended particles, and those nucleating on the upcomer wall. Analyses of bubble growth induced by changes in hydrostatic pressure, mass transfer, and coalescence are presented. Using available information for bubble size distribution in seawater at California locations, it is shown that cavitation will probably have a significant impact on evaporator performance unless a debubbler is provided upstream of the evaporator entrance.

scholarly journals Bubble Nucleation and Growth of Dissolved Gas in Solution Flowing across a Cavitating Nozzle

2015 ◽  
Vol 773-774 ◽  
pp. 304-308 ◽  
Author(s):  
Zhen Hong Ban ◽  
Kok Keong Lau ◽  
Mohd Sharif Azmi
Keyword(s):  
Bubble Dynamics ◽  
Bubbly Flow ◽  
Bubble Formation ◽  
Computational Modelling ◽  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
Supersaturated Solution ◽  
Computational Domain ◽  
Dissolved Gas ◽  
Growth Phenomenon

Computational modelling of dissolved gas bubble formation and growth in supersaturated solution is essential for various engineering applications, including flash vaporisation of petroleum crude oil. The common mathematical modelling of bubbly flow only caters for single liquid and its vapour, which is known as cavitation. This work aims to simulate the bubble nucleation and growth of dissolved CO2 in water across a cavitating nozzle. The dynamics of bubble nucleation and growth phenomenon will be predicted based on the hydrodynamics in the computational domain. The complex interrelated bubble dynamics, mass transfer and hydrodynamics was coupled by using Computational Fluid Dynamics (CFD) and bubble nucleation and growth model. Generally, the bubbles nucleate at the throat of the nozzle and grow along with the flow. Therefore, only the region after the throat of the nozzle has bubbles. This approach is expected to be useful for various types of bubbly flow modelling in supersaturated condition.

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