First-Principles Informed Atomistic-Scale Calculations of Equilibrium Energy Accommodation Coefficients for Aluminum–Noble Gas Systems

2020 ◽  
Vol 124 (13) ◽  
pp. 7182-7195
Author(s):  
Pinki ◽  
Prasanna Kulkarni ◽  
Dilip Srinivas Sundaram
Keyword(s):  
First Principles ◽  
Noble Gas ◽  
Energy Accommodation ◽  
Accommodation Coefficients

Effect of Melting on Energy Accommodation Coefficients of Aluminum–Noble Gas Systems

2020 ◽  
Vol 124 (40) ◽  
pp. 22105-22116
Author(s):  
Jyotishraj Thoudam ◽  
Tejas Mane ◽  
Dilip Sundaram
Keyword(s):  
Noble Gas ◽  
Energy Accommodation ◽  
Accommodation Coefficients

First-principles study of noble gas stability in ThO 2

2017 ◽  
Vol 490 ◽  
pp. 181-187 ◽  
Author(s):  
Kuan Shao ◽  
Han Han ◽  
Wei Zhang ◽  
Hui Wang ◽  
Chang-Ying Wang ◽  
...  
Keyword(s):  
First Principles ◽  
Noble Gas ◽  
First Principles Study

scholarly journals Impact of Noble-Gas Filler Atoms on the Lattice Thermal Conductivity of CoSb3 Skutterudites: First-Principles Modelling

2020 ◽  
Author(s):  
Jianqin Tang ◽  
Jonathan Skelton
Keyword(s):  
Thermal Conductivity ◽  
First Principles ◽  
Thermal Transport ◽  
Noble Gas ◽  
Detailed Balance ◽  
Resonant Scattering ◽  
Acoustic Mode ◽  
Cage Compounds ◽  
Mode Dispersion ◽  
Group Velocities

We present a systematic first-principles modelling study of the structural dynamics and thermal transport in the CoSb<sub>3</sub> skutterudites with a series of noble-gas filler atoms. A range of analysis techniques are proposed to estimate the filler rattling frequencies, to quantify the separate impacts of filling on the phonon group velocities and lifetimes, and to show how changes to the phonon spectra and interaction strengths lead to suppressed lifetimes. The fillers are found to reduce the thermal conductivity of the CoSb<sub>3</sub> framework by up to 15 % primarily by suppressing the group velocities of low-lying optic modes. Calculations show that the filler rattling frequencies are determined by a detailed balance of increasing atomic mass and stronger interactions with the framework, and are a good predictor of their impact on the heat transport. Lowering the rattling frequency below ~1.5 THz by selecting heavy fillers that interact weakly with the framework is predicted to produce a much larger suppression of the thermal transport, by inducing avoided crossings in the acoustic-mode dispersion and facilitating resonant scattering with a consequent large reduction in the lifetimes. Approximate rattling frequencies determined from the harmonic force constants may therefore provide a useful metric for selecting filler atoms to optimise the thermal transport in skutterudites and other cage compounds such as clathrates.

scholarly journals Recombination and chemical energy accommodation coefficients from chemical dynamics simulations: O/O2 mixtures reacting over a β-cristobalite (001) surface

2011 ◽  
Vol 13 (39) ◽  
pp. 17494 ◽  
Author(s):  
Víctor Morón ◽  
Pablo Gamallo ◽  
Ludovic Martin-Gondre ◽  
Cédric Crespos ◽  
Pascal Larregaray ◽  
...  
Keyword(s):  
Chemical Energy ◽  
Chemical Dynamics ◽  
Energy Accommodation ◽  
Accommodation Coefficients ◽  
Dynamics Simulations

Energy accommodation coefficients of internally excited molecules

1981 ◽  
Vol 75 (9) ◽  
pp. 4621-4625 ◽  
Author(s):  
D. R. Anderson ◽  
E.‐H. Lee ◽  
R. H. Pildes ◽  
S. L. Bernasek
Keyword(s):  
Energy Accommodation ◽  
Accommodation Coefficients ◽  
Excited Molecules

scholarly journals Measurement of Heat Transfer from Anodic Oxide Film on Aluminum in High Knudsen Number Flows

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 234 ◽  
Author(s):  
Hiroki Yamaguchi ◽  
Kenji Kito
Keyword(s):  
Heat Transfer ◽  
Oxide Films ◽  
Sample Surface ◽  
Anodic Oxide ◽  
Heat Fluxes ◽  
Molecular Flow ◽  
Sem Images ◽  
Anodic Oxide Films ◽  
Energy Accommodation ◽  
Accommodation Coefficients

The heat transfer in vacuum depends on the gas–surface interaction. In this study, the heat flux from anodic oxide films on aluminum with different anodizing times through a gas confined between two surfaces with different temperatures was studied. We prepared a non-treated surface, a surface with a normal anodizing time of 30 min, and a surface with 90 min, where the formed film would partially dissolve by long time exposure to the solution. The formation of the films was checked by electrical resistance. Scanning electron microscope (SEM) images were obtained for the three sample surfaces. Even though it was difficult to observe the hexagonal cylindrical cell structures on anodic oxide films, the 30 min sample surface was shown to be rough, and it was relatively smooth and powdery for the 90 min sample surface. The heat fluxes from three sample surfaces were measured from the free-molecular to near free-molecular flow regimes, and analyzed to obtain the energy accommodation coefficients. The heat fluxes were well fitted by the fitting curves. The energy accommodation coefficients for both helium and argon increased by anodizing an aluminum sample surface, while they decreased with increasing the anodizing time up to 90 min indicating the dissolution of the film.

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