Contact melting of a phase change material inside a heated parallelepedic capsule

A mathematical model is presented for the contact melting of a subcooled phase change material (PCM) inside a heated parallelepipedic capsule. Results indicate that the melted fraction from close contact melting at the bottom of the capsule is larger, by an order of magnitude, than that from the conduction dominated melting at the top. The melting process is chiefly governed by the magnitude of the Stefan number Ste. It is also strongly influenced by the side dimensions of the capsule L-x and L-z. The total melting time increases linearly with the degree of subcooling R, but its effect is marginal for low and moderate subcooling (R less than or equal to 1.5) and for Ste less than or equal to 0.1, Finally, an analytical expression is determined for the duration of close contact melting of a parallelepipedic PCM block at the melting temperature resting on a heated plate. (C) 2000 Elsevier Science Ltd. All rights reserved.