Convective Instability of Water-ice Layers

Convective Instability of Water-ice Layers PDF Author: Shun Kwei Fung
Publisher:
ISBN:
Category :
Languages : en
Pages : 90

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Convective Instability of Water-ice Layers

Convective Instability of Water-ice Layers PDF Author: Shun Kwei Fung
Publisher:
ISBN:
Category :
Languages : en
Pages : 90

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Thermal Instability and Heat Transfer Characteristics in Water/ice Systems

Thermal Instability and Heat Transfer Characteristics in Water/ice Systems PDF Author: Yin-Chao Yen
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 48

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Book Description
This review discusses problems associated with the anomalous temperature-density relations of water. It covers a) onset of convection, b) temperature structure and natural convective heat transfer, and c) laminar forced convective heat transfer in the water/ice system. The onset of convection in a water/ice system was found to dependent on thermal boundary conditions, not a constant value as in the classical fluids that have a monotonic temperature-density relationship. The water/ice system also exhibits a unique temperature distribution in the melt layer immediately after the critical Rayleigh number is exceeded and soon after it establishes a more or less constant temperature region progressively deepening as the melt layer grows. The constant temperature is approximately 3.2 C for water layers formed from above but varies for melt layers from below. The heat flux across the water/ice interface was found to be a weak power function and to increase linearly with temperature for melted layers from above and below, respectively. Keywords: Density inversion, Heat transfer, Ice, Natural convection, Thermal instability, Water.

Thermal Instability in a Layer of Water Formed by Melting Ice from Below

Thermal Instability in a Layer of Water Formed by Melting Ice from Below PDF Author: Yin-Chao Yen
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 19

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The transition in the mode of heat transfer from conduction to convection in a layer of water formed continuously by melting ice from below has been determined experimentally. This was accomplished by locating the inflection point on the curve relating the water-ice interface (or melting front) and time. Thus, the critical Rayleigh number, Rac, at which convective heat transfer started can be correlated empirically as a function of warm plate temperature. Homogeneous, bubble-free ice was prepared and used in all the experiments. (Author).

Understanding the Growth and Convective Instability of Mushy Layers, with Application to Young Sea Ice

Understanding the Growth and Convective Instability of Mushy Layers, with Application to Young Sea Ice PDF Author: Joseph Hitchen
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The Role of Ice in the Conditional Instability of the Tropical Atmosphere

The Role of Ice in the Conditional Instability of the Tropical Atmosphere PDF Author: Earle Rolfe Williams
Publisher:
ISBN:
Category : Atmospheric thermodynamics
Languages : en
Pages : 60

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Experimental Determination of Heat Transfer Coefficients in Water Flowing Over a Horizontal Ice Sheet

Experimental Determination of Heat Transfer Coefficients in Water Flowing Over a Horizontal Ice Sheet PDF Author: Virgil J. Lunardini
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 98

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Book Description
Experiments to study the melting of a horizontal ice sheet with a flow of water above it were conducted in a 35 m long refrigerated flume with a cross section of 1.2x1.2 m. Water depth, temperature, and velocity were varied as well as the temperature and initial surface profile of the ice sheet. The heat transfer regimes were found to consist of forced turbulent flow at high Reynolds numbers with a transition to free convection heat transfer. There was no convincing evidence of a forced laminar regime. The data were correlated for each of the regimes, with the Reynolds number, Re, or the Grashof number combined with the Reynolds number as Gr/Re to the 2.5 power used to characterize the different kinds of heat transfer. For water flowing over a horizontal ice sheet, the melting heat flux, for low flow velocities, was not found to drop below the value for the free convection case-488.5 W/sq m-as long as the water temperature exceeds 3.4 C. This is significant since the free convection melt values far exceed those for laminar forced convection. At the low flow velocities, the melting flux was not dependent upon the fluid temperature until the water temperature dropped below 3.4 C, when q sub c = 135.7 (Delta T). In general, the heat transfer was found to significantly exceed that of non-melting systems for the same regimes. This was attributed to increased free stream turbulence, thermal instability due to the density maximum of water near 4 C, and the turbulent eddies associated with the generation of a wavy ice surface during the melting.

Interactive Dynamics of Convection and Solidification

Interactive Dynamics of Convection and Solidification PDF Author: S.H. Davis
Publisher: Springer Science & Business Media
ISBN: 940112809X
Category : Science
Languages : en
Pages : 262

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Book Description
The phase transformation from liquid to solid is a phenomenon central to a wide range of manufacturing and natural processes. The presence of phase transformation can drive convection in the melt through the liberation of latent heat, the rejection of solute, and the change of density upon freezing. The fluid mechanics itself can playa central role; the phase transformation can be strongly altered by convective transport in the liquid through the modification of the thermal and solutal environment of the solid-liquid interface; these local fields control the freezing characteristics at the interface. The convection can be generated naturally by buoyancy forces arising from gradients of temperature and concentration in the liquid, by density changes upon freezing, and by thermocapillary and solutocapillary forces on liquid-solid interfaces. The interactive coupling between solidification and convection forms the subject of this volume. Such coupled processes are significant on a large range of scales. Among the applications of interest are the manufacture of single crystals, the processing of surfaces using laser or molecular beams, and the processes of soldering and welding. One wants to understand and predict macrosegregation in castings, transport and fractionation in geological and geophysical systems, and heat accumulation in energy redistribution and storage systems. This volume contains papers presented at the NATO Advanced Research Workshop on "Interactive Dynamics of Convection and Solidification" held in Chamonix, France, March 8-13, 1992.

CRREL Report

CRREL Report PDF Author:
Publisher:
ISBN:
Category : Cold regions
Languages : en
Pages : 550

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Freezing And Melting Heat Transfer In Engineering

Freezing And Melting Heat Transfer In Engineering PDF Author: K. C. Cheng
Publisher: CRC Press
ISBN: 9780891169857
Category : Technology & Engineering
Languages : en
Pages : 824

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Book Description
This volume of papers has been produced in memory of Professor R.R. Gilpin, who was a pioneer in the field of freezing phenomena in ice-water systems. The subject has applications in ice formation in industrial plants, technologies for manufacturing crystals in space for semiconductors and computer chips and atmospheric physics and geophysics.

The Energy Method, Stability, and Nonlinear Convection

The Energy Method, Stability, and Nonlinear Convection PDF Author: Brian Straughan
Publisher: Springer Science & Business Media
ISBN: 0387217401
Category : Mathematics
Languages : en
Pages : 461

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Book Description
Six new chapters (14-19) deal with topics of current interest: multi-component convection diffusion, convection in a compressible fluid, convenction with temperature dependent viscosity and thermal conductivity, penetrative convection, nonlinear stability in ocean circulation models, and numerical solution of eigenvalue problems.