NUMERICAL STUDY OF NATURAL-CONVECTION-DOMINATED MELTING INSIDE UNIFORMLY AND DISCRETELY HEATED RECTANGULAR CAVITIES

Abstract

A numerical study has been conducted for natural-convection-dominated melting inside uniformly and discretely heated rectangular cavities. A computational methodology based on the enthalpy method for the phase change is first presented and validated with experimental data. The model is next employed to determine the effect of the source dimension β and spanη, of the aspect ratio of the cavity A, and of the wall-phase change material thermal diffusivity ratio ā on the melting process. Results show that for a uniformly heated wall, the melting time and the temperature of the wall reach a maximum for A ≈ 10. For A,≤10, convection-dominated melting is enhanced, and the melting time is reduced. For A ≥ 10, the larger heated surface area promotes conduction-dominated melting, and the resulting melting times are also reduced. For discretely heated cavities of aspect ratio A ≤, 3.0 with a low wall thermal diffusivity ratio (ā 1.5(, the source span η is the most influential parameter. For 0.625 ≤ A ≤ 1.6 and -η ≥ 0.4 the melting times are larger, and the top sources quickly overheat. If η ≤ 0.4, the melting times are shorter, and the temperatures of the sources remain equal and moderate during the melting process. Threshold values āmin above which melting becomes independent of the source distribution were determined for cavities of aspect ratios ranging from 0.625 to 10.

Notes

Address correspondence to Professor Marcel Lacroix, Université de Sherbrooke, Département de Génie Mécanique, Sherbrooke, Qulbec J1K 2R1, Cańada. E-mail: [email protected]