Near-Wall Focusing of Phase Change Micro-Particles for Local Heat Transfer Enhancement

Abstract

We report the effect of confining micron-sized phase-change particles to a layer near the heated wall of a parallel plate channel. We developed a numerical model which assumes fully-developed laminar flow and a constant heat flux applied to one wall. Melting of the confined phase-change particles is incorporated in the model using a spatially-dependent and temperature-dependent effective heat capacity. We investigated the effect of channel height, height of the phase-change particle layer, heat flux, and fluid properties on the peak local Nusselt number (Nu*) and the averaged Nusselt number over the melting length (Numelt). Compared to the base Nusselt number for this geometry (Nuo = 5.385), Numelt and Nu* enhancements were determined to be as high as 15% and 45%, respectively. For a constant mass fraction of particles in the phase-change layer, Numelt is optimized when the phase-change particles are confined to within 35% of the channel width. These studies suggest a strategy to enhance heat transfer with phase change particles for various thermal-fluidic systems.