Showing papers on "Stefan number published in 1988"
TL;DR: In this paper, the authors identify the most basic scales and regimes of the phenomenon of melting with natural convection in an enclosure heated from the side and show that the phenomenon consists of a sequence of four regimes: pure conduction regime, mixed regime, convection regime and shrinking solid regime.
209 citations
TL;DR: In this article, a theoretical model to determine the thermal and fluid flow characteristics of a thermal energy storage system using a phase-change material has been developed, which can be used to predict the energy storage behavior of different phase change materials used with different heat transfer fluids, flow geometries, flow rates and temperatures.
Abstract: The concept of a phase-change material-based, thermal energy storage system is often used for different applications. A theoretical model to determine the thermal and fluid flow characteristics of a thermal energy storage system using a phase-change material has been developed. The model can be used to predict the energy storage behavior of different phase-change materials used with different heat transfer fluids, flow geometries, flow rates and temperatures. Results have been obtained for the case where the phase-change material is Na2SO4·10H2O (Glauber's salt) and the heat transfer fluid is water. The variation of the dimensionless temperatures of the fluid and the solid, and the molten fraction of the solid during the phase change process, with dimensionless time, for different values of Biot number, Stefan number, and the flow parameter have been determined. A discussion of the results obtained and the conclusions drawn from them are also given.
17 citations
TL;DR: In this paper, an anti-precipitation experiment was conducted to extend the life cycle of PCM by adding Celite, and also to determine melting heat transfer characteristics of the PCM in a cylindrical heat exchanger with six fins.
Abstract: This study is concerned with anti-precipitation experiments to extend the life cycle of PCM by adding Celite, and also to determine melting heat transfer characteristics experiment of PCM in a PCM cylindrical heat exchanger with six fins. Experimental results are compared with theory to investigate the appropriateness of the unsteadystate two-dimensional heat conduction equation, and the effects of fluid inlet temperature and flowrate on the total melting time of PCM are investigated. Experimental results show that the optimum PCM mixture is 70.5 weight percent of Glauber''s salt and 0.25 weight percent of Celite as thickener, and they are within 5 % agreement with the enthalpy model. It is confirmed that the heat transmission enthalpy model is appropriate for analysis of the melting heat transfer characteristics of PCM. The total melting Fourier number has the following relationships with respect to the Biot number and Stefan number. (NFo)m=0.0551(NBI)-0.343(NSTE)-0.733
4 citations
TL;DR: In this paper, the authors investigated the solidification heat transfer characteristics of phase change energy storage system and showed that the heat transmission enthalpy model is sufficient for the analysis of heat transfer properties of PCM and the total solidification Fourier number is correlated with Biot number and Stefan number.
Abstract: This study is concerned with the solidification heat transfer characteristics of phase change energy storage system. The heat transfer characteristics experiment for the solidification of PCM is performed on the PCM cylindrical heat exchanger with six fins. Experimental results are compared with the theory to investigate the appropriateness of heat conduction equation of PCM and the effect of coolant inlet temperature and flowrate on the total solidification time of PCM are investigated. Experimental results are in good accordance with the theory and they show that heat transmission enthalpy model is sufficient for the analysis of solidification heat transfer characteristics of PCM. The total solidification time of PCM in two dimensional finned PCM cylinder is shortened 5-6 times than that of PCM in one dimensional PCM cylinder. The total solidification Fourier number is correlated with Biot number and Stefan number as following.
3 citations
01 Jan 1988
TL;DR: In this article, numerical and experimental investigations of a capsule-type latent heat exchanger are considered, where the storage medium was a mixture of paraffin wax and aluminum shavings which occupied three percent of the mixture's volume.
Abstract: In this study, numerical and experimental investigations of a capsule-type latent heat exchanger are considered. The storage medium was a mixture of paraffin wax and aluminum shavings which occupied three percent of the mixture's volume. The improvement in the thermal conductivity of the mixture caused by the present of the aluminum shavings was examined experimentally. The thermal performance of a capsule-type latent heat exchanger was evaluated numerically. The results are presented in the form of NTU-effectiveness charts. The design parameters are presented in terms of the Biot number and the Stefan number.
TL;DR: In this article, the melting of ice around a horizontal cylinder of constant heat flux has been studied numerically and the results showed that due to the combined effect induced by the density anomaly of water and the temporal and circumferential variations of the cylinder surface temperature, several different flow structures and the resulting melting patterns were predicted to be quite different from those reported for isothermal boundary conditions.
Abstract: Melting of ice around a horizontal cylinder of constant heat flux has been studied numerically. Computations were performed for modified Stefan number Ste*=0.1, 0.3, 0.4, and 0.5 with modified Rayleigh number Ra* ranging from 104 to 107. Due to the combined effect induced by the density anomaly of water as well as the temporal and circumferential variations of the cylinder surface temperature, several different flow structures and the resulting melting patterns were predicted to be quite different from those reported for isothermal boundary conditions.