Melt Front Enhancement of Phase Change Materials via Nanoparticle Inclusion for Improved Heat Transfer and Cyclability

Abstract

Passive cooling techniques are widely sought-after solutions to thermal management issues in high power electronics due to increased energy dissipation in reduced areas. Phase change materials (PCMs) present a promising secondary passive thermal management opportunity by absorbing a large amount of energy as an isothermal process. This phenomenon can be utilized in various ways as a thermal management tool; including temperature spike alleviation, energy storage, and secondary passive cooling. Though PCMs have promising passive cooling ability, often it is difficult to select an appropriate or effective PCM for the specific application due to deficiencies in a particular material property. Previous studies have demonstrated the ability to alter PCM properties through the homogeneous inclusion of nanoparticles. Thermal conductivity is a particularly important metric for enhancement via nanoparticles due to the typically low conductivity of PCMs with high latent heats. Previous studies demonstrate the successful augmentation of this property. A large limiting factor to enhanced PCM passive cooling is related to the propagation of the melt front, representing the region of large energy absorption. In many cases, the melt front moves too slowly to effectively transfer energy away from the device. Slow material response time can also be problematic in the re-solidification process, limiting cyclability. Work has been conducted to monitor the melt front response to a thermal load. Early in the melting process, conduction dominates the heat transfer mechanism. This paper will examine the impact of nanoparticle inclusion as a means of controlling the melt front propagation. Using nanoparticles to control the composite thermal conductivity should lead to optimization ability of PCM melt characteristics to align with thermal management needs.