scholarly journals Numerical Simulation of Melting Kinetics of Metal Particles during Tapping with Argon-Bottom Stirring

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 901
Author(s):  
Kinnor Chattopadhyay ◽  
Rodolfo Morales-Davila ◽  
Alfonso Nájera-Bastida ◽  
Jafeth Rodríguez-Ávila ◽  
Carlos Rodrigo Muñiz-Valdés
Keyword(s):  
Room Temperature ◽  
Melting Furnace ◽  
Melting Process ◽  
Melting Rate ◽  
Metal Particles ◽  
Melting Kinetics ◽  
Nickel Particles ◽  
Filling Time ◽  
The Impact ◽  
Kinetics Of

Molten steel is alloyed during tapping from the melting furnace to the argon-bottom stirred ladle. The metallic additions thrown to the ladle during the ladle filling time are at room temperature. The melting rates or kinetics of sinking-metals, like nickel, are simulated through a multiphase Euler–Lagrangian mathematical model during this operation. The melting rate of a metallic particle depends on its trajectory within regions of the melt with high or low turbulence levels, delaying or speeding up their melting process. At low steel levels in the ladle, the melting rates are higher on the opposite side of the plume zone induced by the bottom gas stirring. This effect is due to its deviation after the impact of the impinging jet on the ladle bottom. The higher melting kinetics are located on both sides at high steel levels due to the more extensive recirculation flows formed in taller baths. Making the additions above the eye of the argon plume spout increases the melting rate of nickel particles. The increase of the superheat makes the heat flux more significant from the melt to the particle, increasing its melting rate. At higher superheats, the melting kinetics become less dependent on the fluid dynamics of the melt.

Experimental and Theoretical Study on Melting Kinetics of Spherical Aluminum Particles in Liquid Aluminum

2015 ◽  
Vol 1765 ◽  
pp. 139-144
Author(s):  
Marco Ramírez-Argáez ◽  
Enrique Jardón ◽  
Carlos González-Rivera
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Heat Transfer Coefficient ◽  
Process Analysis ◽  
Convective Heat Transfer Coefficient ◽  
Melting Process ◽  
Solid Particles ◽  
Melting Time ◽  
Melting Kinetics ◽  
Kinetics Of

ABSTRACTIn this study a process analysis of the melting process of solid particles in a bath of same composition is performed using both experimental information and theoretical computations. An experimental setup was used to measure the thermal histories and to follow the evolution with time of the size of solid metallic spherical particles being melted in a metallic bath of same composition. For such a purpose, pure aluminum was used during the experiments for both solid particles and liquid bath. A mathematical model was also developed based on first principles of heat transfer to simulate the melting kinetics of a cold metallic spherical particle immersed in a hot liquid bath of same composition. The mathematical model was reasonably validated when compared against the experimental results obtained in this work. A process analysis of the melting process was performed to determine the effect of the initial temperature and size of the solid particle, the bath temperature and the convective heat transfer coefficient on the melting time and on the energy consumption.The analysis showed that the variable presenting the most significant effect on both the melting time and the energy consumption is the convective heat transfer coefficient between the particle and the bath, since an increment in such a parameter accelerates the melting process and saves energy. Therefore, proper stirring of the bath is highly recommended to enhance the melting of metallic alloying additions in the metallic baths.

Coarse-grained molecular simulations of the melting kinetics of small unilamellar vesicles

Soft Matter ◽  
2016 ◽  
Vol 12 (6) ◽  
pp. 1765-1777 ◽  
Author(s):  
Lara A. Patel ◽  
James T. Kindt
Keyword(s):  
Dominant Role ◽  
Molecular Simulations ◽  
Lipid Vesicles ◽  
Melting Rate ◽  
Coarse Grained ◽  
Unilamellar Vesicles ◽  
Melting Kinetics ◽  
Temperature Jumps ◽  
Small Unilamellar Vesicles ◽  
Kinetics Of

Frozen lipid vesicles simulated using a coarse-grained potential and subject to temperature jumps respond by melting on timescales similar to those observed experimentally; changes in curvature stress appear to play a dominant role in controlling the melting rate.

scholarly journals A Study of Electric Field Effect on Melting of Octadecane

2016 ◽  
Vol 17 (2) ◽  
pp. 256-261
Author(s):  
S.G. Orlovskaya ◽  
F.F. Karimova ◽  
M.S. Shkoropado
Keyword(s):  
Electric Field ◽  
Melting Rate ◽  
Melting Time ◽  
Electric Field Effect ◽  
Shape Evolution ◽  
Solid Core ◽  
Droplet Shape ◽  
Melting Kinetics ◽  
Calculation Results ◽  
Kinetics Of

A new approach is developed to study melting kinetics of n-Octadecane. Modelling of heat transfer during the melting of solid particle is described. The calculation results are in good agreement with experimental data on melting duration. The effect of applied electric field on melting kinetics is studied. Almost twofold increase of melting time is found in an electric field of strength E = 82 kv/m. In addition a rotation of a solid core inside a melt is observed, which is a manifestation of Quinke effect. A droplet shape evolution during phase transition is described. It is shown that initially elongated particle is almost spherical near the melting point and elongates again with the temperature rise. This shape evolution is explained by non-monotonous change of surface tension and is connected with rotational phase. Thus a possibility is shown to control a melting rate of normal alkanes using electric field.

The Impact of the Graphite Nanofiber Structure on the Behavior of Supported Nickel

1997 ◽  
Vol 497 ◽  
Author(s):  
C. Park ◽  
R. T. K. Baker
Keyword(s):  
Metal Particles ◽  
Unsaturated Aldehyde ◽  
Catalytic Behavior ◽  
Support Materials ◽  
Crotyl Alcohol ◽  
Nickel Particles ◽  
Different Types ◽  
Hydrogenation Reactions ◽  
The Impact ◽  
Hydrogenation Of Ethylene

ABSTRACTIn the current investigation we have used the hydrogenation of ethylene and crotonaldehyde as probe reactions in an attempt to follow any changes in catalytic behavior induced by supporting nickel on different types of graphite nanofiber support materials. The hydrogenation of the α,β-unsaturated aldehyde to the desired product, crotyl alcohol, is a particularly difficult task since there is a strong tendency to hydrogenate both the C=C and C=O in the reactant molecule. This study is designed to compare the catalytic behavior of the metal particles when dispersed on three types of nanofibers, where the orientation of the graphite platelets within the structures is significantly different in each case. The metal crystallites are located in such a manner that the majority of particles are in direct contact with graphite edge regions. For comparison purposes, the same set of hydrogenation reactions were carried out under similar conditions over γ-Al2O3 supported nickel particles.

Oxidation kinetics of large nickel particles

1999 ◽  
Vol 14 (7) ◽  
pp. 3051-3058 ◽  
Author(s):  
Richard Karmhag ◽  
Gunnar A. Niklasson ◽  
Mats Nygren
Keyword(s):  
Boundary Diffusion ◽  
Metal Particles ◽  
Particle Sizes ◽  
Median Particle Size ◽  
Polycrystalline Nickel ◽  
Thermally Activated ◽  
Nickel Particles ◽  
Median Diameter ◽  
Median Particle ◽  
Kinetics Of

Oxidation of polycrystalline nickel particles with an approximate median diameter of 158 μm has been studied by thermogravimetric measurements in the temperature range 773–1473 K. The oxidation was found to be thermally activated with an apparent activation energy of about 1.9 eV at temperatures below 1073 K and 1.2 eV at higher temperatures. Our data showed the qualitative features expected for oxidation of spherical metal particles. The kinetics was compared with a homogenous field coupled-currents theory for oxidation of spherical metal particles. Calculations using a median particle size or a distribution of particle sizes could only give a satisfactory fit to part of the experimental data. Possible explanations for the deviations in terms of space charge, grain boundary diffusion, grain growth, and sintering are discussed in this paper. Scanning electron microscopy studies of the particles after oxidation showed that a large difference exists in the surface structure and the degree of sintering between the particles oxidized at low and high temperatures.

Investigation of irradiation-induced nucleation processes in silicon and germanium

1995 ◽  
Vol 53 ◽  
pp. 224-225
Author(s):  
Harry A. Atwater ◽  
C.M. Yang ◽  
K.V. Shcheglov
Keyword(s):  
Room Temperature ◽  
Crystal Size ◽  
Initial Distribution ◽  
Engineering Control ◽  
Size Evolution ◽  
Silicon And Germanium ◽  
Ge Quantum Dot ◽  
And Control ◽  
Germanium Quantum Dots ◽  
Kinetics Of

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Solving the Problem of Silicon Dioxide Melting Based on Deviation Model

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Yuhan Sun
Keyword(s):  
Silicon Dioxide ◽  
Blast Furnace Slag ◽  
Melting Process ◽  
Melting Rate ◽  
Dissolution Behavior ◽  
Characteristic Parameters ◽  
Contour Feature ◽  
Time Periods ◽  
Main Component ◽  
Furnace Slag

Abstract: In order to reveal the dissolution behavior of iron tailings in blast furnace slag, we studied the main component of silica in iron tailings. First, edge contour features need to be established to represent the melting process of silica. We choose shape, perimeter, area and generalized radius as objects. By independently analyzing the influence of these four indexes on the melting rate, the area and shape were selected as the characteristic parameters of the edge contour of the silica particles. Then, the actual melting rate of the silica is estimated by the edge contour feature index. Finally, we can calculate the melting rate of the first second of three time periods of 0.00010312mm3/s，0.0002399mm3/s，0.0000538mm3/s.

Kinetics of the Thermal Disappearance of Radicals Formed During the Radiolysis of Aspartic Acid

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihai Contineanu ◽  
iulia Contineanu ◽  
Ana Neacsu ◽  
Stefan Perisanu
Keyword(s):  
Thermal Resistance ◽  
Aspartic Acid ◽  
Room Temperature ◽  
Esr Spectra ◽  
Complex Mechanism ◽  
Radical Species ◽  
Mechanisms Of Formation ◽  
Kinetics Of

The radiolysis of the isomers L-, D- and DL- of the aspartic acid, in solid polycrystalline state, was investigated at room temperature. The analysis of their ESR spectra indicated the formation of at least two radicalic entities. The radical, identified as R3, resulting from the deamination of the acid, exhibits the highest concentration and thermal resistance. Possible mechanisms of formation of three radical species are suggested, based also on literature data. The kinetics of the disappearance of radical R3 indicated a complex mechanism. Three possible variants were suggested for this mechanism.

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