Studies on Heat Transfer From a Vertical Cylinder, With or Without Fins, Embedded in a Solid Phase Change Medium

Abstract

An experimental investigation of melting and cyclic melting and freezing around a vertical cylinder is reported. The studies encompass two cases: a plain vertical cylinder, and a vertical cylinder with fins. In the melting studies, the total heat transfer from the cylinder was measured as a function of time. In addition, measurements have been made of the solid-liquid interface shape after various melting times. In these studies, the solid phase was initially isothermal and either at its fusion temperature or subcooled below the fusion point. The experiments reveal the important influence of natural convection in the liquid phase in both unfinned and finned situations. Subcooling of the solid phase is observed to strongly inhibit heat transfer in the unfinned situation. In the experiment on cyclic melting and freezing, subcooling of the solid phase is once again found to have an important effect on the unfinned situation. Heat transfer from the finned cylinder is much less affected by solid-phase subcooling. All the experiments were performed with 99 percent pure n-eicosane paraffin.

CFD Modeling of the Charging and Discharging of a Shell-and-Tube Latent Heat Storage System for High-Temperature Applications

“…Attempts have been made by various researchers [14,15,18,20,25,26] to develop correlations for the heat transfer coefficient during the quasi-stationary melting regime that can be used in the design of phase-change storage systems. Most of these studies try to represent the Nusselt number (i.e., the dimensionless heat-transfer coefficient) as a function of other dimensionless parameters such as the Rayleigh number, Stephan number, Prandtl number, and the geometrical configuration of the system.…”

The periodic steady state for cyclic energy storage in paraffin wax

“…The agreement between the model and the data is satisfactory both above and below the point where interference occurs. Also plotted in this figure is the data point for the single periodic steady state investigated by Kalhori and Ramadhyani (1985). Their experiment, which involved freezing and melting external to a vertical cylinder, was freezingcontrolled.…”

“…The wall temperature variation was neither a sine wave nor a square wave. Kalhori and Ramadhyani (1985) measured the energy stored and the temperature profiles within a PCM for the periodic steady state established in an annular storage unit with heat transfer to and from the inner cylinder. The freezing period lasted for 15.25 hours with a minimum temperature 13°C below the fusion temperature while the melting period lasted for 7.25 hours with a maximum temperature 11°C above the fusion temperature.…”

Experimental validation of the exact analytical solution to the steady periodic heat transfer problem in a PCM layer

“…The main researches concern the thermal behavior of plates and hollow cylinders in contact with a fluid [2][3][4], phase change storage system of solar energy [5][6][7] and multilayer building walls containing a PCM layer [8]. In the latter case, many studies regard the evaluation of the influence of PCM thermophysical properties and of the PCM thickness on the dynamic thermal characteristics [9][10][11][12][13][14] for different locations.…”