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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 dimensionless film thickness, melting rate, dimensionless time to complete melting, and Nusselt number for the contact melting processes are derived, which can be used for the analysis of contact melting inside different geometric enclosures.
Abstract: The contact melting progress of phase-change material inside the symmetric enclosure with a continuous boundary is generally studied, and a unified treatment for the heat transfer is proposed. The mathematical expressions of the dimensionless film thickness, melting rate, dimensionless time to complete melting, and Nusselt number for the contact melting processes are derived generally, which can be used for the analysis of the contact melting inside different geometric enclosures. By applying the expressions to the analysis of contact melting inside the cylindrical and elliptical tubes, as well as the spherical capsule, the concrete methods and steps are given. It is found that some major results in the published literature are easily deduced and unified in this paper.
5 citations
TL;DR: In this article, phase change material (PCM) suspension was used to improve the heat transfer and energy storage capabilities of thermal systems, and the results showed that the use of a PCM suspension can effectively enhance heat transfer by natural convection.
Abstract: Research on using phase change material (PCM) suspension to improve the heat transfer and energy storage capabilities of thermal systems is booming; however, there are limited studies on the application of PCM suspension in transient natural convection. In this paper, the implicit finite difference method was used to numerically investigate the transient and steady-state natural convection heat transfer in a square enclosure containing a PCM suspension. The following parameters were included in the simulation: aspect ratio of the physical model = 1, ratio of the buoyancies caused by temperature and concentration gradients = 1, Raleigh number (RaT) = 103–105, Stefan number (Ste) = 0.005–0.1, subcooling factor (Sb) = 0–1.0, and initial mass fraction (or concentration) of PCM particles (ci) = 0–0.1. The results showed that the use of a PCM suspension can effectively enhance heat transfer by natural convection. For example, when RaT = 103, Ste = 0.01, ci = 0.1, and Sb = 1, the steady-state natural convection heat transfer rate inside the square enclosure can be improved by 70% compared with that of pure water. With increasing Sb, the Nusselt number can change nonlinearly, resulting in a local optimal value.
5 citations
TL;DR: In this article, a conduction based model for solving the phase change heat transfer problem around a vertical cylinder submersed in a phase change medium is presented. But, the model is based on the average control volume technique and the ADI approach and the results show the effects of the variation of the Biot number, Stefan number, inlet fluid temperature and the ratio of the outer to the inner tube radius on the solidified mass fraction, NTU, effectiveness and the time for complete solidification.
Abstract: This paper presents a conduction based model for solving the phase change heat transfer problem around a vertical cylinder submersed in the phase change medium. The energy equation is coupled to the flow problem by an energy balance. The system of equations is solved numerically by using the average control volume technique and the ADI approach. The results show the effects of the variation of the Biot number, Stefan number, the inlet fluid temperature and the ratio of the outer to the inner tube radius on the solidified mass fraction, NTU, effectiveness and the time for complete solidification.
5 citations
TL;DR: In this paper, an approximate eigenfunction-based solution for the temperature distribution and propagation of the phase change front with time is derived, which may be interpreted as a generalization of the classical quasistationary method.
5 citations
TL;DR: In this article, the process of freeze coating of a polymeric melt onto a two-dimensional flat plate moving continuously in the axial direction is simulated, taking into account the limited heat capacity of the plate, the spatial variation of plate temperature, and the heat convected from the melt to the freeze coat.
Abstract: The process of freeze coating of a polymeric melt onto a two-dimensional flat plate moving continuously in the axial direction is simulated, taking into account the limited heat capacity of the plate, the spatial variation of the plate temperature, and the heat convected from the melt to the freeze coat. To identify the controlling parameters in the process, the system of equations governing the plate temperature and the shape and the temperature of the freeze coat is transformed into dimensionless coordinates. Numerical methods have been used to solve the resulting mathematical model. The history of the spatial variation of the shape of the freeze coat is presented in graphs. The parameters controlling the shape of the freeze coat are identified, and it has been found that the plate-coat diffusivity ratio, a convective heat transfer parameter, Peclet number, Stefan number, and the fusion temperature of the molten fluid are the parameters that control the growth and decay of the freeze-coat layer. The effect of these parameters and the boundary conditions on the behavior of the freeze-coat process is discussed.
5 citations