Topic
Stefan number
About: Stefan number is a research topic. Over the lifetime, 482 publications have been published within this topic receiving 32056 citations.
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TL;DR: In this article, the assumptions used in the analytic solutions of unconstrained melting inside a spherical capsule are closely examined by comparing them with numerical solutions, and the restrictions on low Stefan number and low Rayleigh number of existing analytic solutions are addressed.
Abstract: Analytic solutions are very important for providing physical insight and a basis for the examination of numerical and experimental results. However, analytic approaches are subject to extensive assumptions, so they cannot explain the complex phenomena involved with unconstrained melting. On the discharging conditions in real Thermal energy storage (TES) systems, such as capsule size, wall temperature and capsule materials, the assumptions used in the analytic solutions of unconstrained melting inside a spherical capsule are closely examined by comparing them with numerical solutions. Numerical approaches are more practical to implement all these complex behaviors, thus are used as the basis in the comparison after thorough validation. The restrictions on low Stefan number and low Rayleigh number of existing analytic solutions are addressed.
9 citations
TL;DR: In this article, the authors explored the conditions for the onset of natural convection in subcooled phase change materials (PCMs) in a 2-dimensional experimental system and found that the melting volume at the onset was increased with the center-tube diameter, with shorter times and less liquid PCM required for the start of convection as the Δ T m -based Stefan number increased.
9 citations
01 Dec 1980
TL;DR: In this article, the heat balance integral technique applied to the cylinder gave excellent results when compared to published numerical solutions, and an approximate, general solution has been derived which is reasonably accurate and can be used for any values of the above-mentioned parameters.
Abstract: : No general, analytical solution exists for phase change around a cylinder, thus, approximate methods have been evaluated. The heat balance integral technique applied to the cylinder gave excellent results when compared to published numerical solutions. Graphical solutions are given for phase change about a cylinder for ranges of the Stefan number, superheat parameter, and property value ratios for typical soils. An approximate, general solution has been derived which is reasonably accurate and can be used for any values of the above-mentioned parameters. The effective thermal diffusivity method has been shown to be useful for practical problems of phase change. (Author)
9 citations
TL;DR: In this article, an enthalpy formulation is applied to the solidification process of an arbitrarily shaped casting in a mold-casting system, and the effect of thermal contact resistance existing at the mold casting interface is also studied.
9 citations
01 Jan 1998
TL;DR: In this article, the effect of vertical water movement on the rate of thaw and the thermal regime of the soil is quantified, and an exact similarity solution only occurs when the vertical water velocity is proportional to the rate for thaw, which indicates that seepage flows have little effect upon the thaw process.
Abstract: Most analyses of the thawing of frozen soil are based on purely conductive heat transfer, a very good assumption in most cases, but vertical and horizontal water flows occur frequently in permafrost regions. The effect of vertical water movement on the rate of thaw and the thermal regime of the soil is quantified. An exact similarity solution only occurs when the vertical water velocity is proportional to the rate of thaw. This solution indicates that seepage flows (the magnitude of the water velocity is near that of the rate of thaw) have little effect upon the thaw process. Approximate solutions are also given for the case of constant water velocity, using the heat balance integral and quasi-steady methods; they agree with the exact solution if the Stefan number is not too large. Thaw can be greatly accelerated or retarded if the water velocity (Peclet number) is large. The effect upon thawing for the case of horizontal water flow is less than that for the same magnitude of vertical flow.
9 citations