NUMERICAL SIMULATION OF THE EFFECT OF THE SIZE OF THE NANOPARTICLE ON THE SOLIDIFICATION PROCESS OF NANOPARTICLE-ENHANCEND PHASE CHANGE MATERIALS

Conference Name: Proceedings of the ASME 2012 Summer Heat Transfer Conference
Location: Rio Grande, Puerto Rico
Date: 2012

List of Authors:

Yousef. M. F. EL Hasadi, , J. M. Khodadadi

Abstract

Nanoparticle-enhanced phase change materials (NEPCM) were proposed recently as alternatives to conventional phase change materials due to their enhanced thermophysical properties. In this study, for the first time, the effect of the size of the nanoparticles on the morphology of the solid-liquid interface and evolving concentration, during solidification has been reported numerically. The numerical method that has been used was based on the one-fluid-mixture model. The model takes into account the thermal as well as the solutal convection effects. A square cavity was used in the simulation. The NEPCM was composed of a suspension of copper nanoparticles in water and it was solidified from the bottom with the nanoparticle sizes of 2 and 5nm The temperature difference between the hot and cold sides was 5 degrees centigrade and the loading of the nanoparticles that have been used in the simulation was 10% by mass. The results obtained from the model were compared with those existing in the literature and the comparison was satisfactory. The solid-liquid interface for the case of NEPCM with 5 nm particle size was nearly planer throughout the solidification process. However, for the case of the NEPCM with particle size 2 nm, the solid-liquid interface evolved from planer stable shape to unstable dentritic shape, as the solidification process proceeds on time. This was attributed to the constitutional supercooling effect. It has been observed that the constitutional supercooling effect is more pronounced as the particle size decreases, and also the freezing time increases as the particle size decreases.