Melting of a phase change material in concentric horizontal annuli of arbitrary cross-section

Results are presented of a finite element computational study of the free convection-dominated melting of a pure phase change material contained in concentric horizontal annuli of the following configurations: (a) square external tube with a circular tube inside — annulus type A and (b) circular external tube with a square tube inside — annulus type B. Effects of the Rayleigh number as well as heating of the inside, outside or both walls at a temperature above the melting point of the material were studied. Flow and temperature patterns within the melt, local heat flux distributions at the heating surface and the cumulative energy charged as a function of time are presented and discussed.