An experimental investigation of constrained melting of a phase change material (PCM) in circular geometries, part I: Velocity characterization

Abstract

This study is focused on the detailed characterization of the transient velocity fields of a phase change material (PCM) enclosed in a geometry with a circular cross-section subjected to uniform external heating. Particle image velocimetry (PIV) was used to study the velocity behavior related to the buoyancy-driven convection. The PCM was initially subcooled, and the walls suddenly heated to exceed the melting temperature. Experiments were conducted using Rubitherm RT26 in a quasi-2D circular enclosure at three applied heating conditions. Detailed velocity fields show strong symmetric convective vortices at the sides of the PCM chamber, and a three-dimensional recirculation was detected near the bottom. These structures strongly influence the melting behavior. The results suggest self-similarity in flow behavior between heating conditions. Detailed transient temperature fields and an extended discussion of the associated heat transfer behavior are presented in the companion paper (Part II).