Experimental estimate of energy accommodation coefficient at high temperatures

Altman, Igor; Lee, D.; Song, Junesol; Choi, Mansoo

doi:10.1103/physreve.64.052202

Cited by 22 publications

(4 citation statements)

References 18 publications

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“…The authors were able to solve this puzzle using the small energy accommodation coefficient (EAC) in their heat balance model. Note that this small EAC was theoretically predicted and experimentally demonstrated in previous work [5,6], and it was successfully utilized for the modeling of the nanoparticle growth in different systems [7,8,9].…”

Section: Introductionmentioning

confidence: 59%

“…The asymptotically vanishing value of EAC at high temperatures was derived from the rigorous quantum mechanics model [5] describing energy transfer to the phonon system which distribution does define the temperature of not only solids, but that of liquids as well [16]. The small EAC value (<0.005) was demonstrated in the experiment [6]. At the same time, there is a belief that the EAC of the order of 0.1–1 claimed to be measured by the laser-induced incandescence (LII) technique [17,18] should be used instead.…”

Section: Remarks On Eacmentioning

confidence: 99%

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Burn Time of Metal Nanoparticles

Altman

2019

Materials

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This article will discuss the combustion of metal nanoparticles and explain the burn time dependence on particle size. In contrary to common belief in the power law (tb~d0.3), which, in our knowledge, is simply an experimental fit to data, we propose the logarithmic law (tb~ln(d)) that describes well the known results on nano-aluminum combustion. We derived the logarithmic dependence from a simple model taking into account the energy balance on the surface of a burning metal nanoparticle. The model in question is based on the small energy accommodation coefficient (EAC), which was recently utilized to solve experimental puzzles such as the significant temperature gap between the burning nanoparticle and the environment. A discussion on EAC, which value is important for the correct modeling of nanoparticle combustion, is also included. A way to generalize the considered combustion model is suggested.

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Section: Introductionmentioning

confidence: 59%

Section: Remarks On Eacmentioning

confidence: 99%

Burn Time of Metal Nanoparticles

Altman

2019

Materials

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“…where E is the total energy transferred to the wall and ∆h f the dissociation energy of the recombined molecule. Models of the accommodation coefficient can be found in literature [23][24][25]. On the other hand, the roughness of the surface increases the wet area on which the atomic species can collide and recombine.…”

Section: The Macroscopic Descriptionmentioning

confidence: 99%

Assessment of gas-surface interaction modelling for lifting body re-entry flight design

Farran¹

2018

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My wish is that the reader enjoys this dissertation and that it brings him/her a better understanding on Gas-Surface Interaction (GSI) phenomena. Nonetheless, this journey through the VKI doctoral program has been long, and I wouldn't be able to address this topic without acknowledging people that were by my side during this research, because without them this thesis would not have been possible: A big thank to Olivier Chazot for giving me the opportunity to develop my thesis in the Plasmatron facility. His office was always open and ready for discussion. A special mention to his telephone, most of the time ringing during each one of our conversations. Also to Roberto Flores, director of this thesis in UPC, who allowed me to keep in contact with my university. Following the experimental nature of this dissertation, I would like to mention also the contribution made by Pascal Collin. He did an excelent job running the Plasmatron and installing the probes. I will always remember his desperation when water leaks appear when making the vacuum in the chamber. I thank also the rest of the Plasmatron team: Bernd Helber and Damien Le Quang as radiation experts, and Işil Şakraker as advisor for calorimetric measurements. Many CFD simulations appear in this dissertaion. For that, the advice of Vincent Van Der Haegen, my office mate, has been extremely useful to achieve a converged solution. Also, the flight extrapolation technique developed here deserves my gratitude to Fabio Pinna, whose expertise in CFD helped me to improve my IXV simulations and achieve the "Pinna Certification". I really enjoyed working with them. Other VKI colleagues I want to mention are Alessandro Turchi, who helped me understand many aspects of GSI phenomena, Francesco Panerai who set the basis to develop this dissertation, and Georgios Bellas-Chatzigeordis to whom I encourage to continue with the catalytic model development and implementation in VKI numerical tools. Last but not least, special thanks to my family. They encouraged me to pursue a doctorate degree and supported me in the most difficult moments.

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“…To the best of our knowledge, there are no studies available in the literature on thermal accommodation of oxygen and nitrogen on metal oxide surfaces at elevated temperatures. Probably, the only exception is the work of Altman et al 47 who studied the silica nanoparticles at conditions close to those existing in combustion (temperatures around 2000 K) and found that the accommodation coefficient does not exceed the value of 0.005.…”

Section: -9mentioning

confidence: 99%

Thermal theory of aluminum particle ignition in continuum, free-molecular, and transition heat transfer regimes

Ermoline

2018

Journal of Applied Physics

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Most studies on nano-and micro-sized aluminum particle ignition have been focused on the processes occurring inside particles. In the current paper, thermal ignition of an aluminum particle in the air is simulated with different heat transfer models: continuum, free-molecular, and Fuchs model. A single parabolic oxidation law is assumed in the particle size range from nano-to millimeter diameters. A particle is considered ignited when it reaches the oxide melting point. The criterion defining the limits of validity for each model is the ratio of continuum and free-molecular heat transfer rates. The dependence of ignition temperature T i on the particle size is in qualitative agreement with the experimental trends: T i can have values in the range of 700-1500 K for nanoparticles due to the dominating contribution of a free-molecular heat transfer, and sharp growth of T i with the particle size in the range of 1-100 lm diameter is due to the transitional character of heat transfer. For small values of the accommodation coefficient, ignition may occur in the critical ignition mode with the thermal runaway. The results suggest the importance of non-continuous heat transfer and, in particular, energy accommodation in ignition of nano-and micro-sized particles. Published by AIP Publishing. https://doi.

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Experimental estimate of energy accommodation coefficient at high temperatures

Cited by 22 publications

References 18 publications

Burn Time of Metal Nanoparticles

Burn Time of Metal Nanoparticles

Assessment of gas-surface interaction modelling for lifting body re-entry flight design

Thermal theory of aluminum particle ignition in continuum, free-molecular, and transition heat transfer regimes

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