Experimental and Analytical Study of Contact Melting in a Rectangular Cavity

This paper reports on a detailed investigation of analytical and experimental findings for contact melting in a rectangular cavity with phase change materials (PCM) of n-heptadecane and n-eicosane (research grade purity). Specifically, consideration is given to the rectangular cavity with inside dimensions of 100 x 60 x 50 mm. The temperature of the two side walls and bottom surface of the cavity are maintained constant by circulating water through a highly sensitive thermostat. The other surfaces are subjected to adiabatic conditions. The time-dependent solid-liquid interface contour is measured photographically during the melting process. According to the shadowgraph technique, the maximum displacement on the screen represents the temperature gradient. This temperature gradient on the wall is measured by the shadowgraph method, which results in calculation of the local Nusselt number. This local Nusselt number is used to show the difference between contact melting and fixed melting in the rectangular cavity at the same boundary conditions. Based on observation of the melting phenomena and data obtained, a theoretical model is developed and its solution is derived analytically. For the purpose of data reduction, a scale analysis method is used to find the functional dependence of the dimensionless parameters. The theoretical prediction is compared with experimental data and an excellent agreement is obtained. It is concluded that heat conduction in the melting phase is the controlling effect in the rectangular cavity.