An experimental study on melting heat transfer of paraffin dispersed with Al2O3 nanoparticles in a vertical enclosure

Abstract

Melting experiments in a vertical square enclosure are undertaken with a solid–liquid phase-change material (n-octadecane) dispersed with nanoparticles (Al2O3) as the nano-phase-change-material (nano-PCM). The enclosure has a cross-section dimension of 25 by 25mm and it was 60mm long. The vertical side walls were differentially heated isothermally while the remaining side walls were thermally insulated. The effect of dispersing nanoparticles in the base phase change material (PCM) on the melting heat transfer characteristics in the enclosure is examined for the relevant parameters in the following ranges: the mass particle fraction of nanoparticles, ωp=0, 5, 10wt.%; the Rayleigh number, Raf=1.71×106–5.67×107; the Stefan number, Stef=0.037–0.108; and the subcooling parameter, Sb=0.042–0.537. The surface-averaged heat transfer results obtained during the melting experiments indicate that natural convection heat transfer into the melted region of the enclosure tends to degrade markedly with increasing mass fraction of nanoparticles dispersed in the nano-PCM, when compared with that of the base PCM.