scholarly journals Numerical Investigation on the Evolution of Thin Liquid Layer and Dynamic Behavior of an Electro-Thermal Drilling Probe during Close-Contact Heat Transfer

2021 ◽  
Vol 11 (8) ◽  
pp. 3443
Author(s):  
Chan Ho Jeong ◽  
Kwangu Kang ◽  
Ui-Joon Park ◽  
Hyung Ju Lee ◽  
Hong Seok Kim ◽  
...  
Keyword(s):  
Liquid Layer ◽  
Close Contact ◽  
Melting Process ◽  
Transient Behavior ◽  
Liquid Films ◽  
Melting Rate ◽  
Contact Melting ◽  
Contact Heat ◽  
Navier Stokes Equation ◽  
Thermal Drilling

This study investigates the transient behavior of an electro-thermal drilling probe (ETDP) during a close-contact melting process within a glacier. In particular, the present work analyzes the effect of the tip temperature on the formation of molten thin liquid films and the subsequent rate of penetration (ROP) through numerical simulation. We used the commercial code of ANSYS Fluent (v.17.2) to solve the Reynolds-averaged Navier–Stokes equation, together with an energy equation considering the solidification and melting model. The ROP of the drilling probe is determined based on the energy balance between the heating power and melting rate of ice. As the results, the ETDP penetrates the ice through a close-contact melting process. The molten liquid layer with less than 1 mm of thickness forms near the heated probe tip. In addition, the ROP increases with the heated temperature of the probe tip.

Close-Contact Melting Inside an Elliptical Cylinder

2000 ◽  
Vol 122 (4) ◽  
pp. 192-195 ◽  
Author(s):  
Sergei A. Fomin ◽  
Alexander V. Wilchinsky ◽  
Takeo S. Saitoh
Keyword(s):  
Mathematical Model ◽  
Thermal Energy ◽  
Close Contact ◽  
Energy Systems ◽  
Elliptic Cylinder ◽  
Melting Process ◽  
Melting Rate ◽  
Contact Melting ◽  
Approximate Mathematical Model ◽  
Characteristic Scales

An approximate mathematical model of contact melting in a horizontal elliptic cylinder is developed. The main characteristic scales and nondimensional parameters that describe the principal features of the melting process are found. It is shown that melting rate depends on the shape of the capsule. This is especially important for the design of practical latent heat thermal energy systems. [S0199-6231(00)00504-9]

An Experimental and Analytical Study of Close-Contact Melting

1986 ◽  
Vol 108 (4) ◽  
pp. 894-899 ◽  
Author(s):  
M. K. Moallemi ◽  
B. W. Webb ◽  
R. Viskanta
Keyword(s):  
Approximate Solution ◽  
Surface Temperature ◽  
Cross Section ◽  
Analytical Study ◽  
Close Contact ◽  
Rectangular Cross Section ◽  
Melting Rate ◽  
Contact Melting ◽  
Series Of Experiments ◽  
Convection Dominated

Close-contact melting was investigated by performing a series of experiments in which blocks of solid n-octadecane (with circular or rectangular cross section) were melted by a horizontal planar heat source at constant surface temperature. Close contact between the source and the solid prevailed throughout the experiments by permitting the uncontained solid to descend under its own weight while squeezing the melt out of the gap separating it from the source. The velocity of the solid was measured and is reported as a function of the instantaneous weight of the solid. Effects of the surface temperature of the source and radius of the solid on its temporal velocity are also reported. A closed-form approximate solution is developed for the motion of solid and predictions are compared with the experimental data. The results for the solid velocity are correlated in terms of the governing parameters of the problem as revealed by the approximate solution. Compared with natural convection-dominated melting from below (solid confined and contained in a rectangular cavity) close contact gives rise to approximately a sevenfold increase in the melting rate of the solid.

scholarly journals Contact Melting of Metals Explained via the Theory of Quasi-Liquid Layer

2020 ◽  
Vol 11 (1) ◽  
pp. 51
Author(s):  
Alexey V. Melkikh
Keyword(s):  
Liquid Phase ◽  
Liquid Layer ◽  
Solid Phase ◽  
Melting Rate ◽  
Contact Melting ◽  
Melting Time ◽  
Metal Atoms ◽  
Quasi Liquid Layer

It has been shown that the contact melting rate for metals is determined by the fact that at least one of them has a quasi-liquid layer on the surface. As a result, the diffusion of metal atoms occurs in the liquid phase, and not in the solid phase, which determines the characteristic contact melting time (seconds and minutes).

The Influence of a Harmonic Motion on a Melting Process With Natural Convection

2013 ◽  
Author(s):  
Ruben Avila ◽  
Eduardo Ramos
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Transfer Rate ◽  
Liquid Layer ◽  
Transfer Rate ◽  
Fluid Layer ◽  
Melting Process ◽  
Spectral Element ◽  
Melting Rate ◽  
Liquid System

We study the heat transfer rate in an oscillatory, two dimensional solid-liquid system which is melted from below. As the phase change process takes place, the height of the fluid layer in the lower part of the cavity is continuously enlarged. The influence of the angular frequency of the motion (Taylor number) and the melting rate (Stefan number) on: (i) the heat transfer in the liquid (Nusselt number), (ii) the temperature field and (iii) the shape of the interface, is analyzed. The governing equations together with the Stefan condition at the interface are solved by using a spectral element method. It is observed that as the height of the liquid layer increases, a non-steady unicellular flow appears, and it leads to an oscillatory behaviour of the Nusselt number. As the height of the liquid layer increases further, the onset of the thermal convection and its instabilities modify the shape of the interface, and the heat transfer rate in the molten material. We find that (i) for large Stefan numbers, the heat is transported mostly along the inclined walls, while for low Stefan numbers, a Rayleigh-Bénard type convection is dominant, and (ii) for large Taylor numbers, the motion induced by the oscillation is small, resulting in a Nusselt number that decreases monotonously as a function of time, in contrast, for small Taylor numbers, an oscillatory Nusselt number is displayed.

Close-contact melting on an isothermal surface with the inclusion of non-Newtonian effects

2019 ◽  
Vol 865 ◽  
pp. 720-742 ◽  
Author(s):  
Y. Kozak ◽  
Yi Zeng ◽  
Rabih M. Al Ghossein ◽  
J. M. Khodadadi ◽  
G. Ziskind
Keyword(s):  
Yield Stress ◽  
Layer Thickness ◽  
Close Contact ◽  
Melting Rate ◽  
Analytical Approximation ◽  
Contact Melting ◽  
Viscoplastic Fluid ◽  
Molten Layer ◽  
Isothermal Surface ◽  
Dimensionless Groups

The present study deals with a theoretical investigation of a close-contact melting (CCM) process involving a vertical cylinder on a horizontal isothermal surface, where the liquid phase is a non-Newtonian viscoplastic fluid that behaves according to the Bingham model. Accordingly, a new approach is formulated based on the thin layer approximation and different quasi-steady process assumptions. By analytical derivation, an algebraic equation that relates the molten layer thickness and the solid bulk height is developed. The problem is then solved numerically, coupled with another equation for the melting rate. The new model shows that as the yield stress increases the melting rate decreases and the molten layer thickness increases. It is found that under certain conditions, the model can be reduced to a form that allows an analytical solution. The approximate model predicts an exponential dependence of both the melt fraction and the molten layer thickness. Comparison between the numerical and analytical solutions shows that the analytical approximation provides an excellent estimation for sufficiently large values of the yield stress. Dimensional analysis, which is supported by the analytical model results, reveals the dimensionless groups that govern the problem. For the general case, the melt fraction is a function of two dimensionless groups. For the analytical approximation, it is shown that the melt fraction is governed by a single dimensionless group and that the molten layer thickness is governed by two dimensionless groups.

Numerical analysis of the close-contact heat transfer of the electro-thermal drilling probes for glacier-ice exploration

2021 ◽  
Vol 35 (3) ◽  
pp. 1309-1317
Author(s):  
Ui-Joon Park ◽  
Kwangu Kang ◽  
Hyung Ju Lee ◽  
Chan Ho Jeong ◽  
Jin-Yeong Park ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Close Contact ◽  
Contact Heat ◽  
Contact Heat Transfer ◽  
Thermal Drilling ◽  
Glacier Ice

Experiments on Melting of Unfixed Ice in a Horizontal Cylindrical Capsule

1987 ◽  
Vol 109 (2) ◽  
pp. 454-459 ◽  
Author(s):  
B. W. Webb ◽  
M. K. Moallemi ◽  
R. Viskanta
Keyword(s):  
Natural Convection ◽  
Flow Structure ◽  
Close Contact ◽  
Flow Regimes ◽  
Melting Process ◽  
Contact Melting ◽  
Cylinder Wall ◽  
Liquid Region ◽  
Inversion Point ◽  
Heated Cylinder

Melting of unrestrained ice in a horizontal cylindrical capsule has been investigated experimentally to determine the interaction of fluid flow induced by motion of the solid and natural convection with density inversion of the water–ice system. During the melting process the ice is drawn by buoyancy to the top of the heated cylinder where close-contact melting occurs. Natural convection-dominated melting whose intensity depends on wall temperature prevails in the liquid region below. Three distinct flow regimes were identified for the cylinder wall temperatures of 3.5, 7, and 12° C studied. The flow structure for temperatures below the inversion point is similar to that for melting of unfixed n-heptadecane reported previously. Photographs of flow regimes are presented, and dependence of the solid–liquid interface morphology on the flow structure is discussed.

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