Interdiffusion behavior under a temperature gradient field in a poly(ethylene-co-hexene)/poly(ethylene-co-butene) system

RSC Advances ◽  
2015 ◽  
Vol 5 (74) ◽  
pp. 60015-60023 ◽  
Author(s):  
Haifeng Shi ◽  
Hua Jiang ◽  
Guoqiang Fan ◽  
Zhaohui Yang ◽  
Xiaohua Zhang
Keyword(s):  
Temperature Gradient ◽  
Thermal Gradient ◽  
Gradient Field ◽  
Polymer Diffusion ◽  
System P ◽  
Poly Ethylene ◽  
Polymer Migration

The in-plane thermal gradient accelerates polymer migration through the enhancement in polymer diffusion along the direction of the temperature gradient.

Thermo-structural analysis of cryogenic tanks with common bulkhead configuration

2021 ◽  
pp. 095441002110247
Author(s):  
S Sumith ◽  
R Ramesh Kumar
Keyword(s):  
Structural Analysis ◽  
Temperature Gradient ◽  
Thermal Gradient ◽  
Load Transfer ◽  
Thermal Analyses ◽  
Positive Margin ◽  
Heat Transfer Analysis ◽  
Liquid Oxygen ◽  
Launch Vehicles ◽  
Element Analysis

In launch vehicles, cryogenic propulsion stages store liquid oxygen (LOX) at 76 K and liquid hydrogen (LH2) at 20 K, generally in two separate insulated tanks connected through tubular truss components. Consequently, load transfer from the LH2 tank to the LOX tank is very much localized, resulting in a nonoptimal design. This article presents an alternative single tankage design using a common bulkhead (CBH) to enhance the payload capability, which enables maintaining LH2 temperature within a specified temperature when exposed to a temperature gradient. A sandwich insulator using aramid honeycomb embedded with polyimide foam keeps the LH2 temperature within 20 ± 1 K is proposed, based on transient heat transfer analysis for 1000 s. The foam-filled honeycomb core is treated as equivalent foam in the analysis as the thermal conductivity of the core and the foam is quite close. The efficacy of the insulator is established by an experiment to measure the back wall temperature when liquid nitrogen is loaded on the top skin of the panel, and the insulator maintains a temperature gradient of 123 K for 1000 s. A good agreement is obtained between the transient finite element analysis results with experimental data. An externally insulated LOX tank configuration with an optimum length of the skirt–cylinder where the temperature reaches 80 K is arrived at based on slosh, buckling, and thermal analyses. No thermal gradient is found across the thickness of the skirt, while the thermal gradient is observed along the length of the skirt as anticipated. An integrated thermo-structural analysis of the cryo-system is carried out considering temperature-dependent material properties. A positive margin for the skirt is obtained. A payload gain of 366 kg is estimated based on the present study for the new design option with a CBH and skirt as compared to the traditional tubular truss arrangements.

A Theoretical Study of the Temperature Gradient Effect on the Soret Coefficient in n-Pentane/n-Decane Mixtures Using Non-Equilibrium Molecular Dynamics

2020 ◽  
Vol 45 (4) ◽  
pp. 319-332
Author(s):  
Xiaoyu Chen ◽  
Ruquan Liang ◽  
Yong Wang ◽  
Ziqi Xia ◽  
Lichun Wu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Temperature Gradient ◽  
Thermal Gradient ◽  
Linear Response ◽  
Theoretical Study ◽  
Soret Coefficient ◽  
Thermal Gradients ◽  
Gradient Effect ◽  
Non Equilibrium Molecular Dynamics ◽  
Non Equilibrium

AbstractThe effect of the temperature gradient on the Soret coefficient in n-pentane/n-decane (n-C5/n-C10) mixtures was investigated using non-equilibrium molecular dynamics (NEMD) with the heat exchange (eHEX) algorithm. n-Pentane/n-decane mixtures with three different compositions (0.25, 0.5, and 0.75 mole fractions, respectively) and the TraPPE-UA force field were used in computing the Soret coefficient ({S_{T}}) at 300 K and 1 atm. Added/removed heat quantities (ΔQ) of 0.002, 0.004, 0.006, 0.008, and 0.01 kcal/mol were employed in eHEX processes in order to study the effect of different thermal gradients on the Soret coefficient. Moreover, a phenomenological description was applied to discuss the mechanism of this effect. Present results show that the Soret coefficient values firstly fluctuate violently and then become increasingly stable with increasing ΔQ (especially in the mixture with a mole fraction of 0.75), which means that ΔQ has a smaller effect on the Soret coefficient when the temperature gradient is higher than a certain thermal gradient. Thus, a high temperature gradient is recommended for calculating the Soret coefficient under the conditions that a linear response and constant phase are ensured in the system. In addition, the simulated Soret coefficient obtained at the highest ΔQ within three different compositions is in great agreement with experimental data.

Effect of thermal gradient field with phase change on crystal morphologies of HDPE during GAIM process

2010 ◽  
Vol 39 (9) ◽  
pp. 385-391 ◽  
Author(s):  
L. Wang ◽  
W. Yang ◽  
L. Huang ◽  
B. Yang ◽  
N. Sun ◽  
...  
Keyword(s):  
Phase Change ◽  
Thermal Gradient ◽  
Gradient Field

Studying Binary Solvent Mixtures as Mobile Phase for Thermal Gradient Interactive Chromatography (TGIC) of Poly(ethylene-stat-1-octene)

2014 ◽  
Vol 53 (39) ◽  
pp. 15183-15191 ◽  
Author(s):  
Dibyaranjan Mekap ◽  
Tibor Macko ◽  
Robert Brüll ◽  
Rongjuan Cong ◽  
A. Willem deGroot ◽  
...  
Keyword(s):  
Thermal Gradient ◽  
Mobile Phase ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Binary Solvent Mixtures ◽  
Poly Ethylene

scholarly journals Влияние висмута на свойства упругонапряженных гетероструктур AlGaInAsP<Bi>/InP

2019 ◽  
Vol 53 (8) ◽  
pp. 1110
Author(s):  
М.Л. Лунина ◽  
Л.С. Лунин ◽  
Д.Л. Алфимова ◽  
А.С. Пащенко ◽  
Э.М. Данилина ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Quantum Yield ◽  
Temperature Gradient ◽  
Indium Phosphide ◽  
Luminescence Properties ◽  
Gradient Field ◽  
Epitaxial Layers ◽  
Structural Perfection ◽  
External Quantum Yield

AbstractThe results of growing elastically stressed AlGaInAsP〈Bi〉 thin epitaxial layers from the liquid phase on indium phosphide substrates in a temperature-gradient field are discussed. The effect of bismuth on the structural perfection, the luminescence properties, and the external quantum yield of AlGaInAsP〈Bi〉/InP heterostructures is investigated.

Experimental crystallization of volcanic glasses in a thermal gradient field

1979 ◽  
Vol 26 (1-2) ◽  
pp. 17-28 ◽  
Author(s):  
G.N. Kirov ◽  
V. Pechigargov ◽  
E. Landzheva
Keyword(s):  
Thermal Gradient ◽  
Gradient Field ◽  
Volcanic Glasses

Phase Field Modeling of Solidification in Single Component Systems

2017 ◽  
Author(s):  
Sepideh Kavousi ◽  
Dorel Moldovan
Keyword(s):  
Heat Flux ◽  
Temperature Gradient ◽  
Power Law ◽  
Phase Field ◽  
Thermal Gradient ◽  
Solidification Rate ◽  
Single Component ◽  
Effect Of Temperature ◽  
Phase Field Modeling ◽  
Field Modeling

Using phase field modeling simulation approach we investigate the effect of various parameters on the primary and secondary dendrite arm spacing during directional solidification in a single component system. In previous studies the effect of temperature gradient was assumed to be negligible in the transversal directions with a temperature rate equal to the product of thermal gradient and solidification rate. In our study the temperature field is obtained from energy conservation equation by considering the balance of latent heat released in the regions where solidification occurs and energy dissipation due to directional temperature gradient as boundary condition. In our simulations, we implemented a numerical method that enables the investigation of solidification in larger domains. Specifically, the temperature and the order parameter equations are solved only in the domains close to the solidification front; approach that reduces the computational costs significantly. We investigate the interplay and the effect of thermal gradient, solidification rate, undercooling temperature, and the cooling heat flux on arm spacing. By using a well-established power law relation the primary and secondary arm spacing are calculated for various solidification parameters. We also show that, for large heat fluxes, the secondary arm spacing is almost constant for different undercooling temperatures; behavior that demonstrates the need for correction of the power law relation by including the effect of heat flux.

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