Inclination-Induced Direct-Contact Melting in a Circular Tube

Melting of a phase-change medium encapsulated in a circular tube was investigated experimentally at a succession of tube inclinations relative to the vertical. It was found that repeatable and continuous direct contact of the melting solid with the tube wall was established at an inclination of about 15 deg and that further increases in inclination had virtually no effect on the melting results. Direct contact gave rise to substantial enhancements (up to a factor of two) in the amount of melted mass and in the energy transfer, relative to those for natural-convection-dominated melting (e.g., for the vertical tube case). The energy transfer was subdivided into two components, the latent heat supplied to the melting interface and the sensible heat stored in the liquid melt, and a general correlation of the two components was achieved. With regard to the pattern of melting, it was observed that the continuous-contact mode was preceded by a period of partial contact. During that period, the solid was tipped toward the wall while pivoting about its lower edge.