Journal of the Korean Crystal Growth and Crystal Technology (한국결정성장학회지)

The Korea Association of Crystal Growth (한국결정성장학회)
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Effect of accelerational perturbations on physical vapor transport crystal growth under microgravity environments

  • Choi, Jeong-Gil (Department of Nano-Bio Chemical Engineering, Hannam University) ;
  • Lee, Kyong-Hwan (Energy Conversion Research Department, Korea Institute of Energy Research) ;
  • Kwon, Moo-Hyun (Department of Chemistry, Woosuk University) ;
  • Kim, Geug-Tae (Department of Nano-Bio Chemical Engineering, Hannam University)
  • Published : 2006.10.31
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Abstract

For $P_B=50,\;{\Delta}T=10K$, Ar=5, Pr=2.36, Le=0.015, Pe=1.26, Cv=1.11, the intensity of solutal convection (solutal Grashof number $Grs=3.44x10^4$) is greater than that of thermal convection (thermal Grashof number $Grt=1.81x10^3$) by one order of magnitude, which is based on the solutally buoyancy-driven convection due to the disparity in the molecular weights of the component A($Hg_2Cl_2$) and B(He). With increasing the partial pressure of component B from 10 up to 200 Torr, the rate is decreased exponentially. The convective transport decreases with lower g level and is changed to the diffusive mode at 0.1 $g_0$. In other words, for regions in which the g level is 0.1 $g_0$ or less, the diffusion-driven convection results in a parabolic velocity profile and a recirculating cell is not likely to occur. Therefore a gravitational acceleration level of less than 0.1 $g_0$ can be adequate to ensure purely diffusive transport.

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References

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