Heat conduction across 1D nano film: Local thermal conductivity and extrapolation length

摘要

We analyze the short scale effects on the 1D steady-state heat conduction across a nano film using discrete variable model (DVM). The DVM allows for both diffusive and ballistic components of energy transport and can be used to study far from local equilibrium systems when the characteristic space and time scales of interest are of the order of or even smaller than the mean free path and mean free time of energy carriers, respectively. This is particularly important for the performance evaluation of modern thermal nano systems and microdevices, which usually operate on an extremely short space scale. Thermal extrapolation length and local (position-dependant) thermal conductivity are introduced to virtually eliminate the temperature jump at the boundaries with thermal baths. We also analyze the effects of the film thickness on the bulk effective thermal conductivities and effective boundary conductance to describe the transition from diffusive to ballistic heat transfer. The results are compared with other theories and available experimental data.