Non-monotonic heat dissipation phenomenon in close-packed 2D and 3D hotspot system

Abstract

Transient heat dissipation in close-packed quasi-2D nanoline and 3D nanocuboid hotspot systems is studied based on phonon Boltzmann transport equation. Different from previous intuitive understanding of micro/nano scale heat conduction, it is found that the heat dissipation efficiency is not monotonic when the distance between adjacent nanoscale heat sources decreases. The heat dissipation efficiency reaches the highest value when the distance between adjacent nanoscale heat sources is comparable to the phonon mean free path. It is a competition result of two thermal transport processes: quasiballistic transport when phonons escape from the nanoscale heat source and the scattering among phonons originating from adjacent nanoscale heat source.