Étude numérique de la fusion dans des enceintes rectangulaires chauffées uniformément ou discrètement par les parois latérales conductrices

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 dimensions β and span η, of the aspect ratio of the cavity A and of the wall-PCM thermal diffusivity ratio $\text{α}$ on the melting process. Results show the benefits of using discrete heat sources instead of a uniformly heated wall. For high aspect ratio enclosures (A ≳ 4), configurations leading to well controlled source temperatures and relatively long melting times have been obtained. For cavities of aspect ratio A ≲ 4.0, the source span η is the most influential parameter. If η ≲ 0.45, the melting times are shorter and the temperatures of the sources remain equal and moderate during the melting process. Threshold values $\text{α}{}_{\mathrm{<mtext>min</mtext>}}$ above which melting becomes independent of the source distribution were determined for cavities of various aspect ratios.