Flow and morphological conditions associated with unidirectional solidification of aqueous ammonium chloride

Journal Article · Mon Nov 01 04:00:00 EST 1993 · Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States)

DOI:https://doi.org/10.1115/1.2911358· OSTI ID:5677192

Magirl, C S; Incropera, F P ^[1]

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1. Purdue Univ., West Lafayette, IN (United States)

Using a 27 percent aqueous ammonium chloride solution as a transparent analog, shadowgraph and dye injection techniques have been employed to observe flow and morphological conditions associated with unidirectional solidification (UDS) from below. Dendritic crystals, which initially form at the cold surface, reject lighter, solute deficient fluid, and the attendant instability is manifested by finger-type double-diffusive convection phenomena. As a two-phase (solid/liquid), or mushy, region grows from the bottom surface, vertical channels develop in the mushy region, and solutal plumes that emanate from the channels are characterized primarily by an ascending, oscillatory motion and secondarily by wisps of fluid, which detach and descend from bends in the plumes. In time, double-diffusive convection layers also form in the melt. From a numerical simulation of the process, it is concluded that the channels originate from perturbations at the liquid interface, which cause localized remelting and create conditions conducive to development of the channels. 30 refs., 9 figs.

• DOE Contract Number: FG02-87ER13759
• OSTI ID: 5677192
• Journal Information: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States), Journal Name: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States) Vol. 115:4; ISSN 0022-1481; ISSN JHTRAO
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
AMMONIUM CHLORIDES
AMMONIUM COMPOUNDS
AMMONIUM HALIDES
CHLORIDES
CHLORINE COMPOUNDS
CONVECTION
CRYSTALLIZATION
CRYSTALS
DENDRITES
DISPERSIONS
DYES
ENERGY TRANSFER
HALIDES
HALOGEN COMPOUNDS
HEAT TRANSFER
HYDROGEN COMPOUNDS
MASS TRANSFER
MATHEMATICAL MODELS
MIXTURES
MORPHOLOGY
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
SOLIDIFICATION
SOLUTIONS
WATER