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Experimental study of directional solidification of aqueous ammonium chloride solution

Published online by Cambridge University Press:  26 April 2006

C. F. Chen  and
Falin Chen
C. F. Chen
Affiliation:
Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721, USA
Falin Chen
Affiliation:
Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721, USA Present address: The Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan, 10764 ROC.
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Abstract

Directional solidification experiments have been carried out using the analogue casting system of NH4Cl-H2O solution by cooling it from below with a constant-temperature surface ranging from - 31.5°C to + 11.9 °C. The NH4Cl concentration was 26% in all solutions, with a liquidus temperature of 15 °C. It was found that finger convection occurred in the fluid region just above the mushy layer in all experiments. Plume convection with associated chimneys in the mush occurred in experiments with bottom temperatures as high as + 11.0 °C. However, when the bottom temperature was raised to + 11.9 °C, no plume convection was observed, although finger convection continued as usual. A method has been devised to determine the porosity of the mush by computed tomography. Using the mean value of the porosity across the mush layer and the permeability calculated by the Kozeny-Carman relationship, the critical solute Rayleigh number across the mush layer for onset of plume convection was estimated to be between 200 and 250.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 227 , June 1991 , pp. 567 - 586
Copyright
© 1991 Cambridge University Press

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References

Barrett, H. H. 1981 Radiological Imaging, pp. 334, 376. Academic.
Beckermann, C. & Viskanta, R. 1988 Double-diffusive convection during dendritic solidification of a binary mixture. Physico Chem. Hydrodyn. 10, 195–213.Google Scholar
Bennon, W. D. & Incropera, F. P. 1987 A continuum model for momentum, heat and species transport in binary solid—liquid phase change systems: II. Application to solidification in a rectangular boundary. Int. J. Heat Mass Transfer 30, 2171–2187.Google Scholar
Copley, S. M., Giamei, A. F., Johnson, S. M. & Hornbecker, M. F. 1970 The origin of freckles in unidirectionally solidified castings. Metall. Trans. 1, 2193–2204.Google Scholar
Fisher, K. M. 1981 The effects of fluid flow on the solidification of industrial castings and ingots. PhysicoChem. Hydrodyn. 2, 311–326.Google Scholar
Fowler, A. G. 1985 The formation of freckles in binary alloys. IMA J. Appl. Maths 35, 159–174.Google Scholar
Giamei, A. F. & Kear, B. H. 1970 On the nature of freckles in nickel-base superalloys. Metall. Trans. 1, 2185–2192.Google Scholar
Glicksman, M. E., Coriell, S. R. & McFadden, G. B. 1986 Interaction of flows with crystal—melt interface. Ann. Rev. Fluid Mech. 18, 307–335.Google Scholar
Heinrich, J. C. 1988 Numerical simulations of thermosolutal instability during directional solidification of a binary alloy. Comput. Meth. Appl. Mech. Engng 69, 65–88.Google Scholar
Hills, R. N., Loper, D. E. & Roberts, P. H. 1983 A thermodynamically consistent model of the mushy zone. Q. J. Mech. Appl. Maths 36, 505–539.Google Scholar
Huppert, H. E. & Worster, M. G. 1985 Dynamic solidification of a binary alloy. Nature 314, 703–707.Google Scholar
Jackson, K. A., Hunt, J. D., Uhlmann, D. R. & Seward, T. P. 1966 On the origin of the equiaxed zone in castings. Trans. Metall. Soc. AIME 236, 149–158.Google Scholar
Kear, B. H. 1986 Advanced metals. Sci. Am. 255, 159–167.Google Scholar
Mcdonald, R. J. & Hunt, J. D. 1969 Fluid motion through the partially solid regions of a casting and its importance in understanding A-type segregation. Trans. Metall. Soc. AIME 245, 1993–1996.Google Scholar
Mcdonald, R. J. & Hunt, J. D. 1970 Convective fluid motion within the interdendritic liquid of a casting. Metall. Trans. 1, 1787–1788.Google Scholar
Mclean, M. 1983 Directionally Solidified Materials for High Temperature Service. London: The Metals Society.
Mullins, W. W. & Sekerka, R. F. 1964 Stability of a planar interface during solidification of a dilute binary alloy. J. Appl. Phys. 35, 444–451.Google Scholar
Poirier, D. R. 1987 Permeability to flow of interdendritic liquid in columnar—dendritic alloys.. Metall. Trans. B 18, 245–255.Google Scholar
Roberts, P. H. & Loper, D. E. 1983 Toward a theory of the structure and evolution of a dendrite layer. In Stellar and Planetary Magnetism (ed. A. M. Soward), pp. 329–349. Gordon and Breach.
Sample, A. K. & Hellawell, A. 1984 The mechanism of formation and prevention of channel segregation during alloy solidification.. Metall. Trans. A 15, 2163–2173.Google Scholar
Sarazin, J. R. & Hellawell, A. 1988 Channel formation in Pb-Sn, Pb-Sb and Pb-Sn-Sb alloy ingots and comparison with the system NH4Cl-H2O.. Metall. Trans. A 19, 1861–1871.Google Scholar
Sprawls, P. 1987 Physical Principles of Medical Imaging. Frederick, MD: Aspen.
Stern, M. E. 1960 The ‘salt fountain’ and thermohaline convection. Tellus 12, 172–175.Google Scholar
Weast, R. C. 1974 Handbook of Chemistry and Physics, p. D-81. CRC Press.
Withjack, E. M. 1987 Computed tomography for work-property determination and fluid-flow visualization. SPE-16951. Soc. Petrol. Engrs.Google Scholar
Withjack, E. M. & Akervoll, A. 1988 Computer tomography studies of 3-D miscible displacement behavior in a laboratory five-spot model, SPE-18096, Soc. Petrol. Engrs.
Wooding, R. A. 1959 The stability of a viscous liquid in a vertical tube containing porous materials.. Proc. R. Soc. Lond. A 252, 120–134.Google Scholar
Worster, M. G. 1986 Solidification of an alloy from a cooled boundary. J. Fluid Mech. 167, 481–501.Google Scholar