scholarly journals Melting behavior of pseudoknots containing adjacent GC and AT rich domains

2017 ◽  
Vol 5 (1) ◽  
pp. 4
Author(s):  
Calliste Reiling-Steffensmeier ◽  
Mikenzie Nordeen ◽  
Luis A Marky
Keyword(s):  
Melting Behavior

Modeling fine particles and alkali metal compound behavior in a kraft recovery boiler

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 9-14 ◽  
Author(s):  
AINO LEPPÄNEN ◽  
ERKKI VÄLIMÄKI ◽  
ANTTI OKSANEN
Keyword(s):  
Alkali Metal ◽  
Computational Models ◽  
Fine Particles ◽  
Black Liquor ◽  
Melting Behavior ◽  
Metal Compound ◽  
Effect Of Temperature ◽  
Particle Model ◽  
Boiler Furnace ◽  
Recovery Boiler

Under certain conditions, ash in black liquor forms a locally corrosive environment in a kraft recovery boiler. The ash also might cause efficiency losses and even boiler shutdown because of plugging of the flue gas passages. The most troublesome compounds in a fuel such as black liquor are potassium and chlorine because they change the melting behavior of the ash. Fouling and corrosion of the kraft recovery boiler have been researched extensively, but few computational models have been developed to deal with the subject. This report describes a computational fluid dynamics-based method for modeling the reactions between alkali metal compounds and for the formation of fine fume particles in a kraft recovery boiler furnace. The modeling method is developed from ANSYS/FLUENT software and its Fine Particle Model extension. We used the method to examine gaseous alkali metal compound and fine fume particle distributions in a kraft recovery boiler furnace. The effect of temperature and the boiler design on these variables, for example, can be predicted with the model. We also present some preliminary results obtained with the model. When the model is developed further, it can be extended to the superheater area of the kraft recovery boiler. This will give new insight into the variables that increase or decrease fouling and corrosion

scholarly journals Reproduction of melting behavior for vitrified hillforts based on amphibolite, granite, and basalt lithologies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
John S. McCloy ◽  
José Marcial ◽  
Jack S. Clarke ◽  
Mostafa Ahmadzadeh ◽  
John A. Wolff ◽  
...  
Keyword(s):  
Iron Age ◽  
Glass Production ◽  
Melting Behavior ◽  
Source Rocks ◽  
Ex Situ ◽  
Maximum Temperature ◽  
Heating And Cooling ◽  
Heat Treated ◽  
Granitoid Rocks ◽  
Dark Glass

AbstractEuropean Bronze and Iron Age vitrified hillforts have been known since the 1700s, but archaeological interpretations regarding their function and use are still debated. We carried out a series of experiments to constrain conditions that led to the vitrification of the inner wall rocks in the hillfort at Broborg, Sweden. Potential source rocks were collected locally and heat treated in the laboratory, varying maximum temperature, cooling rate, and starting particle size. Crystalline and amorphous phases were quantified using X-ray diffraction both in situ, during heating and cooling, and ex situ, after heating and quenching. Textures, phases, and glass compositions obtained were compared with those for rock samples from the vitrified part of the wall, as well as with equilibrium crystallization calculations. ‘Dark glass’ and its associated minerals formed from amphibolite or dolerite rocks melted at 1000–1200 °C under reducing atmosphere then slow cooled. ‘Clear glass’ formed from non-equilibrium partial melting of feldspar in granitoid rocks. This study aids archaeological forensic investigation of vitrified hillforts and interpretation of source rock material by mapping mineralogical changes and glass production under various heating conditions.

Individual and integrated assessment of topological parameters influencing the melting behavior of a triple concentric tube heat exchanger

2021 ◽  
Vol 40 ◽  
pp. 102708
Author(s):  
Seyed Keyvan Nateghi ◽  
Mohammad Amin Erfani Moghaddam ◽  
Mohammad Hossein Jahangir ◽  
Davoud Domiri Ganji
Keyword(s):  
Heat Exchanger ◽  
Integrated Assessment ◽  
Melting Behavior ◽  
Tube Heat Exchanger ◽  
Topological Parameters

scholarly journals Crystallization of Polymers under the Influence of an External Force Field

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2078
Author(s):  
Rajdeep Singh Payal ◽  
Jens-Uwe Sommer
Keyword(s):  
External Force ◽  
Melting Behavior ◽  
Mechanical Work ◽  
Stem Length ◽  
Heat Of Fusion ◽  
Strong Increase ◽  
Lamellar Thickness ◽  
Equilibrium System ◽  
External Force Field ◽  
Work Done

We simulated the crystallization and melting behavior of entangled polymer melts using molecular dynamics where each chain is subject to a force dipole acting on its ends. This mimics the deformation of chains in a flow field but represents a well-defined equilibrium system in the melt state. Under weak extension within the linear response of the chains, the mechanical work done on the system is about two orders of magnitude smaller as compared with the heat of fusion. As a consequence, thermodynamic and simple arguments following the secondary nucleation model predict only small changes of the crystalline phase. By contrast, an increase of the stem length up to a factor of two is observed in our simulations. On the other hand, the lamellar thickening induced by the external force is proportional to the increase of the entanglement length in the melt prior to crystallization as measured by the primitive path method. While the mechanical work done on the system is only a small perturbation for thermodynamics of polymer crystallization, the change of the primitive path is large. This suggests that a strong increase in the lamellar thickness induced, by external deformation, a topological rather than a thermodynamic origin.

Phase Separation of β-SN in Strained, Compositionally Metastable Ge1-xSnx Alloys

1995 ◽  
Vol 398 ◽  
Author(s):  
Joshua W. Kriesel ◽  
Susanne M. Lee
Keyword(s):  
Phase Separation ◽  
Electron Microprobe ◽  
Rf Sputtering ◽  
Melting Behavior ◽  
Solubility Limit ◽  
X Ray Diffraction ◽  
Solid Solubility Limit ◽  
Transformation Mechanisms ◽  
Subsequent Phase ◽  
Kinetics Of

ABSTRACTUsing rf sputtering and post-deposition annealing in a differential scanning calorimeter (DSC), we manufactured bulk (4000 nm) films of crystalline Ge0.83Sn0.17. This Sn concentration is much greater than the solid solubility limit of Sn in Ge (x ≤ 0.01). Continued annealing thermally induces Sn phase separation from the alloy, limiting the ultimate attainable grain size in the metastable crystals. We examine, here, the mechanisms and kinetics of the processes limiting the size of the Ge0.83Sn0.17 polycrystals. From a combination of DSC, electron microprobe, and x-ray diffraction (XRD) measurements, we propose phase transformation mechanisms corresponding to crystallization of amorphous Ge0.83Sn0.17, crystallization of an as-yet unidentified phase of Sn, and phase separation of Sn from the Ge1-xSnx crystals. We were unable to observe the unidentified phase of Sn in XRD, but the phase must be present in the material to account for the quantitative discrepancies (as much as 8 at.%) in Sn percentages determined from each of the DSC, XRD, and electron microprobe measurements. Our models for the various transformation kinetics were corroborated by the subsequent phase-separated Sn melting behavior observed in the DSC: two Sn melting endotherms, one of which was 20–100°C lower than the bulk melting temperature of Sn. This depressed temperature endotherm we speculate represents liquefaction of nanometer-sized (β–Sn clusters.

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