Showing papers on "Stefan number published in 1995"
TL;DR: In this paper, a detailed review of Joef Stefan's research on solid-liquid phase changes published in six treatises between the years 1889 and 1891 is presented, which are related to the broader context of his interest in transport phenomena, particularly liquid-gas phase changes and chemical reactions.
Abstract: This paper presents a detailed review of Jo~ef Stefan's research on solid-liquid phase changes published in six treatises between the years 1889 and 1891. His achievements on this subject are related to the broader context of his interest in transport phenomena, particularly liquid-gas phase changes and chemical reactions in the years 1873 and 1889 respectively. Stefan's eponymous work is placed in perspective between the present and the first experimental and analytical attempts to describe the solid-liquid phase change by the pioneers Blake in the 17th, and Lamt, Clapeyron and Neumann in the 18th century. In honour of Stefan's work involving moving and free boundaries, the concepts of the Stefan problem and the Stefan number are widely used nowadays. The primary intention of this paper is to attempt to complete and unify the information on the historical roots which led to these two terms.
88 citations
TL;DR: In this paper, a numerical solution using the BEM for freezing and melting problems involving multiple moving phase fronts was developed for a cylindrical problem with the inner surface subjected to a convective environment where the temperature changes between values above and below the freeze temperature of the phase change material.
Abstract: In this paper, multiple front phase change problems in one-dimensional cylindrical systems are investigated. The objective is to develop a numerical solution using the BEM for freezing and melting problems involving multiple moving fronts. Multiple moving phase fronts arise when the phase change material (PCM) is subjected to alternate driving temperatures that cause the surface temperature of the PCM to change back and forth across the phase change temperature. This kind of problem is highly nonlinear at the phase fronts that separate alternate liquid and solid layers with different properties. Fully implicit time discretization is applied to ensure numerically stable results. Numerical results are presented for a cylindrical problem with the inner surface subjected to a convective environment where the temperature changes between values above and below the freeze temperature of the PCM. This condition could occur in ice thermal storage systems. The numerical behaviour of the creation and collapse of the moving fronts is investigated by changing the Stefan number, Biot number, initial temperature, the cycling time length and the time step size.
11 citations
TL;DR: In this paper, the authors solved the two-dimensional Stefan problem of solidification in a half-space, where the heat flux at the wall is a slightly varying function of position along the wall, by means of a large Stefan number approximation (which turns out to be equivalent to a small time solution).
10 citations
TL;DR: In this paper, the cold energy release characteristics of a fine capsulated latent-heat storage material-water mixture as a latent heat storage material having a low melting point of the core material (pentadecane, C15H32, freezing point 283.1 K).
Abstract: This paper deals with cold energy release characteristics of a fine capsulated latent-heat storage material-water mixture as a latent-heat-storage material having a low melting point of the core material (pentadecane, C15H32, freezing point 283.1 K). A direct-contact heat exchange method for an air-fine capsulated latent heat storage material-water mixture was selected to investigate the cold energy release characteristics from the mixture layer including the solidified core latent-heat-storage materials. The temperature effectiveness, the sensible-heat release time and the latent-heat release time were measured as experimental parameters. Useful nondimensional correlation equations for those parameters were derived in terms of nondimensional level of the mixture layer dimension, Reynolds number for air flow, Stefan number and heat capacity ratio.
3 citations
TL;DR: In this article, solidification and flow characteristics of high-density polyethylene flowing in a rectangular cavity having a cooling wall are investigated experimentally, and the useful non-dimensional equations which predict the amount of polyethylenes and the time required for injecting the polymethylene into the cavity, are derived as a function of Reynolds number, cooling temperature ratio and Stefan number.
Abstract: Solidification and flow characteristics of molten high-density polyethylene flowing in a rectangular cavity having a cooling wall are investigated experimentally. Experiments are carried out under various parameters of molten polyethylene temperature, flow velocity of the polyethylene, cooling wall temperature and the thickness of the cavity. The obtained results reveal that the solidification layer formation of the polyethylene is affected by flow behavior, polyethylene temperature and cooling wall temperature. The useful non-dimensional equations, which predict the amount of polyethylene and the time required for injecting the polyethylene into the cavity, are derived as a function of Reynolds number, cooling temperature ratio and Stefan number.
2 citations
TL;DR: In this article, the problem of phase change material (PCM) melting using a heating plate made of porous medium is investigated theoretically, and the melting velocity under a critical condition is obtained analytically as a function of four dimensionless parameters.
Abstract: The problem of melting a phase-change material (PCM) using a heating plate made of porous medium is investigated theoretically. Fluid flowing through a plate made of porous medium is governed by Darcy's law. As PCM and the heating plate approach each other, under typical conditions, part of the melting liquid will be squeezed out, and the remaining part will flow out through the porous medium. However, under a critical condition, it is found that all the melting liquid flows out through the porous medium, and PCM is steadily melted by contact with the porous heating plate, which in turn is pushed by PCM under a given finite force. The melting velocity under this critical condition is obtained analytically as a function of four dimensionless parameters. It is possible for the melting velocity in the critical condition to be higher than that for the case of the nonporous heating plate. The critical condition above which the melting velocity is enhanced by using the porous heating plate is shown in the diagram composed of four dimensionless parameters : porosity, Stefan number, thermal conductivity of porous plate material and particle diameter of sphere model for the porous medium.
2 citations
31 Dec 1995
TL;DR: In this article, integral solutions are derived and analytically solved for ice formation and melting outward a pipe wall, with internal and external convection, showing that the ice or water layer thickness increases with the pipe radius but decreases with the convection heat transfer coefficients.
Abstract: Outward formation and melting of ice around the external wall of a coil-tubing is common in ice-storage tanks which use indirect brine solution (e.g. ethylene or propylene glycol water mixtures) to freeze the water and melt the ice around a build-in spiral coil-tubing heat-exchanger. In this paper, Integral Solutions are derived and analytically solved for ice formation and melting outward a pipe wall, with internal and external convection. Parametric analysis show the effect of the pipe radius, the Stefan number, and the convection heat transfer coefficients, on the ice formation and melting thickness layer. It was found that the ice or water layer thickness increases with the pipe radius but decreases with the convection heat transfer coefficients. The Stefan number has no significant effect. This model can be useful as a limiting case to validate freezing-melting problems outward tubing.
1 citations