Synthesis of supported nanoparticles in supercritical fluids by supercritical fluid reactive deposition: Current state, further perspectives and needs

2018 ◽  
Vol 134 ◽  
pp. 176-183 ◽  
Author(s):  
Michael Türk ◽  
Can Erkey
Keyword(s):  
Supercritical Fluid ◽  
Supercritical Fluids ◽  
Reactive Deposition ◽  
Supported Nanoparticles ◽  
Current State

Generation and Propagation of Thermally Induced Acoustic Waves in Supercritical Fluids: Numerical and Experimental Results

2010 ◽  
Author(s):  
Bakhtier Farouk ◽  
Zhieheng Lei
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Fluid ◽  
Supercritical Fluids ◽  
Acoustic Waves ◽  
Rapid Heating ◽  
Time Dependent ◽  
Cylindrical Chamber ◽  
Thermally Induced ◽  
Supercritical Carbon

The behavior of thermally induced acoustic waves generated by the rapid heating of a bounding solid wall in a closed cylindrical chamber filled with supercritical carbon dioxide is investigated numerically and experimentally. A time-dependent one-dimensional problem is considered for the numerical simulations where the supercritical fluid is contained between two parallel plates. The NIST Reference Database 12 is used to obtain the property relations for supercritical carbon dioxide. The thermally induced pressure (acoustic) waves undergo repeated reflections at the two confining walls and gradually dissipate. The numerically predicted temperature of the bulk supercritical fluid is found to increase homogeneously (the so called piston effect) within the domain. The details of generation, propagation and dissipation of thermally induced acoustic waves in supercritical fluids are presented under different heating rates. In the experiments, a resistance-capacitance circuit is used to generate a rapid temperature increase in a thin metal foil located at one end of a closed cylindrical chamber. The time-dependent pressure variation in the chamber and the temperature history at the foil are recorded by a fast response measurement system. Both the experimental and numerical studies predict similar pressure wave shapes and profiles due to rapid heating of a wall.

scholarly journals Creation of interfaces in composite/hybrid nanostructured materials using supercritical fluids

2015 ◽  
Vol 4 (6) ◽  
Author(s):  
Oana Pascu ◽  
Samuel Marre ◽  
Cyril Aymonier
Keyword(s):  
Surface Chemistry ◽  
Size Distribution ◽  
Nanostructured Materials ◽  
Supercritical Fluid ◽  
Supercritical Fluids ◽  
Chemical Deposition ◽  
Good Control ◽  
Present Review ◽  
Batch Mode ◽  
Distribution Composition

AbstractBy structuring matter at the nano level using highly versatile nanotechnology approaches and apparatus, multifunctionalities with manifestation of enhanced and/or novel useful properties could be attained. The challenges in nanoengineering are the ability to tune the nano-object characteristics (size, distribution, composition, and surface chemistry) and to have a good control on the possible synergy created at the interfaces, especially in the case of complex multifunctional materials. Surface nanoengineering goes hand in hand with the creation of interfaces between nano-objects – either inorganic or hybrid ones – and a closer look in this direction is essential. The present review aims at presenting the possibilities of surface nanoengineering by versatile approaches, namely supercritical fluids processes. Two main routes of nanostructuration, each containing three concepts, will be discussed: supercritical fluid chemical deposition performed in batch mode and continuous supercritical fluid synthesis. Both approaches can be used to access interesting materials with desired properties, with the choice of process depending on what the readers are pursuing.

Supercritical fluid infusion of silver into polyimide films of varying chemical composition

1997 ◽  
Vol 12 (11) ◽  
pp. 3127-3133 ◽  
Author(s):  
J. Rosolovsky ◽  
R. K. Boggess ◽  
A. F. Rubira ◽  
L. T. Taylor ◽  
D. M. Stoakley ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Supercritical Fluid ◽  
Supercritical Fluids ◽  
Strong Correlation ◽  
Strong Dependence ◽  
Silver Complexes ◽  
Polyimide Films ◽  
Time Intervals ◽  
Fluid Infusion ◽  
Ketonic Group

Polyimides can be infused with silver complexes by the use of supercritical fluids. Highly reflective polyimide films were formed by infusing (1,5-cyclooctadiene-1,1,1,5,5,5-hexafluoroacetylacetonato)silver(I) [Ag(COD) (HFA)] into a number of polyimides and then thermally curing those films at 300 °C for time intervals between 30 min and 3 h. Reflectivities of the films exhibited strong dependence on the infusion and cure conditions as well as on the type of polyimide used. The highest reflectivity of 67.1% was achieved with a silvered film prepared from 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride (BTDA) and oxydianiline (ODA) infused at 5000 psi, 100 °C, for 30 min and cured for 1 h at 300 °C. Reflectivities of silvered surfaces of other polyimides investigated varied from 39% to 61%. A strong correlation between the presence of a ketonic group in the polyimide structure and the formation of mirror surfaces was detected.

Effect of Natural Convection on Thermal Energy Storage in Supercritical Fluids

2013 ◽  
Author(s):  
Reza Baghaei Lakeh ◽  
Adrienne S. Lavine ◽  
H. Pirouz Kavehpour ◽  
Gani B. Ganapathi ◽  
Richard E. Wirz
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Natural Convection ◽  
Energy Storage ◽  
Supercritical Fluid ◽  
Supercritical Fluids ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Thermal Storage

Heat transfer to the storage fluid is a critical subject in thermal energy storage systems. The storage fluids that are proposed for supercritical thermal storage system are organic fluids that have poor thermal conductivity; therefore, pure conduction will not be an efficient heat transfer mechanism for the system. The current study concerns a supercritical thermal energy storage system consisting of horizontal tubes filled with a supercritical fluid. The results of this study show that the heat transfer to the supercritical fluid is highly dominated by natural convection. The buoyancy-driven flow inside the storage tubes dominates the flow field and enhances the heat transfer dramatically. Depending on the diameter of the storage tube, the buoyancy-driven flow may be laminar or turbulent. The natural convection has a significant effect on reducing the charge time compared to pure conduction. It was concluded that although the thermal conductivity of the organic supercritical fluids are relatively low, the effective laminar or turbulent natural convection compensates for this deficiency and enables the supercritical thermal storage to charge effectively.

Solvatochromic parameters and solubilities in supercritical fluid systems

1993 ◽  
Vol 71 (11) ◽  
pp. 1834-1840 ◽  
Author(s):  
Mark L. O'Neill ◽  
Peeter Kruus ◽  
Robert C. Burk
Keyword(s):  
Supercritical Fluid ◽  
Supercritical Fluids ◽  
Spectroscopic Studies ◽  
Solvatochromic Parameters ◽  
Solubility Prediction ◽  
Fluid Systems ◽  
Supercritical Fluid Solvents ◽  
Opposite Order ◽  
Solvent Systems ◽  
Solvent Power

Spectroscopic studies of the compound 2-nitroanisole in supercritical fluids CO2 and N2O show that π* values vary linearly with density. The solubility trends in these single component supercritical fluid solvents qualitatively followed the trends in solvent power predicted from π*. However, the relative solvent power predicted for CO2 and N2O based on π* resulted in an opposite order to what was determined experimentally through solubility measurements. The π* parameter may be of some use for solubility prediction if only a limited set of solute–solvent systems are considered. Measurements of π*, especially those in binary supercritical fluid solvents, suggest that π* could be a valuable tool for probing the solute-organized cybotactic region.

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