Spherical Phase-Change Energy Storage With Constant Temperature Heat Injection

Storage of thermal energy due to latent heat involved during outward radial melting of a phase-change material contained in a spherical shell is solved using variational, integral and quasi-steady methods. At uniform temperature heat is applied to inner surface. These methods provide closed-form solutions in the Stefan number, an independent parameter. The results for total energy storage, the phase-change depth and their rate obtained from these approximate analyses do not vary significantly.