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International Heat Transfer Conference 15

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

MD Simulation on Cryogenic Sublimation Dynamics of Dry Ice Nanoparticles

Yi-Min Chen
Beijing Key Laboratory for Solid Waste Utilization and Management, Dept. of Energy and Resources Engineering, College of Engineering, Peking University

Lin Chen
Department of Aerospace Engineering, Tohoku University, 6-6-01, Aramaki-aza Aoba, Aoba-ku, Sendai 980-8579, Japan

DOI: 10.1615/IHTC15.nmm.009418
pages 5599-5612

KEY WORDS: Nano/Micro scale measurement and simulation, Two-phase/Multiphase flow, Numerical simulation, Refrigeration, cryogenics


Nanoscale particles may play an important role in the property of solid-gas two-phase flow, as their sublimation, collision and other physical behaviors usually differ from macroscopic ones. In this paper, the sublimation and collision of carbon dioxide nanoscale particles are investigated by means of molecular dynamics simulation method basing on the EPM2 model. In the case of sublimation, nanoscale carbon dioxide particles of different size (side lengths ranging from 1.126nm-3.378nm) and a nanoscale dry ice film (thickness 5.6nm) are heated by constant heat fluxes. For smaller particles, the solid-gas interface of nanoscale particles is ambiguous, and the sublimation can be rapid and isotropic. For larger particles, the thermodynamics behaviors are closer to the macroscopic ones. During the sublimation of the nanoscale dry ice film, the energy of the interface is at the same level as the interior under lower temperature. Under a high enough temperature, the energy of the interface rapidly increases, and the crystal sublimates rapidly. In the case of collision, particles of different sizes (side lengths ranging from 0.84nm-5.35nm) and collision velocities (ranging from 100 m/s-1000 m/s) are investigated. The bullet particle is given an initial velocity and shot into a targeted particle which has identical temperature and geometry. Under low velocity, collided particles will adhere to each other. Larger Initial velocity results in instant sublimation of the surface layer of the particles after the collision. Further increase/decrease of the collision velocity can lead to other interesting consequences that result in either deformation or combination of both particles.

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