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THE TRANSITION FROM NATURAL-CONVECTION-CONTROLLED FREEZING TO CONDUCTION-CONTROLLED FREEZING.

Author(s) : SPARROW E. M., RAMSEY J. W., HARRIS J. S.

Type of article: Article

Summary

EXPERIMENTS WERE PERFORMED TO STUDY THE TRANSITION BETWEEN FREEZING CONTROLLED BY NATURAL CONVECTION IN THE LIQUID ADJACENT TO A FREEZING INTERFACE AND FREEZING CONTROLLED BY HEAT CONDUCTION IN THE SOLIDIFIED MATERIAL. THE FREEZING TOOK PLACE ON A COOLED VERTICAL TUBE IMMERSED IN AN INITIALLY SUPERHEATED LIQUID CONTAINED IN AN ADIABATIC-WALLED VESSEL. AT EARLY AND INTERMEDIATE TIMES, TEMPERATURE DIFFERENCES THROUGHOUT THE LIQUID INDUCE A VIGOROUS NATURAL CONVECTION MOTION WHICH RETARDS FREEZING, BUT THE TEMPERATURE DIFFERENCES DIMINISH WITH TIME AND NATURAL CONVECTION EBBS. AT LARGE TIMES, THE FREEZING RATE IS FULLY CONTROLLED BY HEAT CONDUCTION IN THE SOLIDIFIED MATERIAL. THE FROZEN SPECIMENS FOR SHORT AND INTERMEDIATE FREEZING TIMES ARE SMOOTH-SURFACED AND TAPERED, WHILE THOSE FOR LARGE TIMES ARE STRAIGHT-SIDED AND HAVE SURFACES THAT ARE OVERLAID WITH A THICKET OF LARGE DISCRETE CRYSTALS. THESE CHARACTERISTICS CORRESPOND RESPECTIVELY TO ZING AND CONDUCTION-CONTROLLED FREEZING. AT EARLY TIMES, THE MEASURED MASS OF THE FROZEN MATERIAL IS IDENTICAL TO THAT FOR NATURAL-CONVECTION-CONTROLLED FREEZING. AT LATER TIMES, THE FROZEN MASS TENDS TO APPROACHTHAT FOR CONDUCTION CONTROLLED FREEZING, BUT A RESIDUAL DEFICIT REMAINS.

Details

  • Original title: THE TRANSITION FROM NATURAL-CONVECTION-CONTROLLED FREEZING TO CONDUCTION-CONTROLLED FREEZING.
  • Record ID : 1982-0046
  • Languages: English
  • Source: J. Heat Transf. - vol. 103 - n. 1
  • Publication date: 1981/02
  • Document available for consultation in the library of the IIR headquarters only.

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