Intensification of convective heat exchange in anomalously viscous media by the application of artificial periodic roughness

1979 ◽  
Vol 36 (1) ◽  
pp. 16-20
Author(s):  
Yu. G. Nazmeev
Keyword(s):  
Heat Exchange ◽  
Convective Heat ◽  
Convective Heat Exchange ◽  
Viscous Media

scholarly journals Hydrodynamics and heat exchange of crystal pulling from melts. Part I: Experimental studies of free convection mode

2019 ◽  
Vol 5 (3) ◽  
pp. 91-100
Author(s):  
Vladimir S. Berdnikov
Keyword(s):  
Heat Exchange ◽  
Convective Heat ◽  
Capillary Flow ◽  
Crystallization Front ◽  
Experimental Studies ◽  
Convective Heat Exchange ◽  
Czochralski Technique ◽  
Study Results ◽  
Front Shape ◽  
Prandtl Numbers

This work is a brief overview of experimental study results for hydrodynamics and convective heat exchange in thermal gravity capillary convection modes for the classic Czochralski technique setup obtained at the Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences. The experiments have been carried out at test benches which simulated the physics of the Czochralski technique for 80 and 295 mm diameter crucibles. Melt simulating fluids with Prandtl numbers Pr = 0.05, 16, 45.6 and 2700 have been used. Experiments with transparent fluids have been used for comparing the evolution of flow structure from laminar mode to well-developed turbulent mode. Advanced visualization and measurement methods have been used. The regularities of local and integral convective heat exchange in the crucible/melt/crystal system have been studied. The experiments have shown that there are threshold Grashof and Marangoni numbers at which the structure of the thermal gravity capillary flow undergoes qualitative changes and hence the regularities of heat exchange in the melt change. The effect of melt hydrodynamics on the crystallization front shape has been studied for Pr = 45.6. Crystallization front shapes have been determined for the 1 × 105 to 1.9 × 105 range of Grashof numbers. We show that the crystallization front shape depends largely on the spatial flow pattern and the temperature distribution in the melt.

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