Nanostructure-driven thermal switch using molecular simulations

Abstract

A thermal switch is a basic building block to design various advanced thermal management systems including electronic packaging, waste heat recovery, cryogenic cooling, and new applications, e.g., thermal logic gates. Majority of existing thermal switches have been demonstrated in large scales (mm to cm), but these may not be ideal to provide viable thermal management solutions in micro/nanoscale applications which require a small size with a fast transient response. To address this challenge, a new nanostructure-driven thermal switch mechanism is demonstrated in argon-filled nanogaps with/without nanoposts (one surface only) through a controlled adsorption-capillary transition at given pressure. Grand Canonical Monte Carlo (GCMC) simulation combined with Non-equilibrium Molecular Dynamics (NEMD) simulations is employed to examine the heat flux across the nanogap at given pressure and to calculate the degree of thermal switch, S. Smax ∼ 65 is found with a fast transient response, ∼ 10 ns. We also found that S increases as the height of the nanoposts increases and the empty space between the nanoposts decreases. This work also shows that a stronger interatomic potential between the solid and fluid particles results in having the thermal switch effect in a wider temperature operating window.