Re-estimation of thermal contact resistance considering near-field thermal radiation effect

TL;DR

This paper re-estimates thermal contact resistance by incorporating near-field thermal radiation effects using fluctuational electrodynamics, revealing significant radiation contributions at submicron roughness scales at room temperature.

Contribution

It introduces a theoretical model that combines contact conduction and near-field radiation, considering surface roughness spectra, to improve TCR estimation.

Findings

Near-field radiation significantly affects TCR at submicron roughness.

Thermal radiation contribution increases with surface roughness.

The model aligns with experimental data for aluminum and alumina.

Abstract

Thermal contact has always been a hot issue in many engineering fields and thermal contact resistance (TCR) is one of the important indicators weighing the heat transfer efficiency among the interfaces. In this paper, the contact heat transfer of conforming rough surfaces is theoretically re-estimated considering both the heat transfer from contact and non-contact regions. The fluctuational electrodynamics (an ab initio calculation) is adopted to calculate the thermal radiation. The contribution of contact regions is estimated by the CMY TCR model and further studied by modelling specific surfaces with corresponding surface roughness power spectrum (PSD). Several tests are presented where aluminum and amorphous alumina are mainly used in the simulations. Studies showed that there exists a significant synergy between the thermal conduction and near-field thermal radiation at the interface in a certain range of effective roughness. When the effective roughness is near to the scales of submicron, the near-field radiation effect should not be neglected even at room temperature.