Comparison of Heat Conduction and Radiation of Nano-Size Gaps

Gas gaps are common structures in many sensors and MEMS. It is usually regarded that heat conduction plays a dominant role when the gap size reduces and thermal radiation between surfaces is negligible. This work compares the heat dissipated by heat conduction with that by thermal radiation under different temperatures and on various scale levels. It is found that the heat flux by thermal radiation can exceed that by heat conduction. Furthermore, a regime map is plotted to recognize the relative importance of heat conduction and thermal radiation at different gap size and temperature. The impact of the thermal accommodation efficient for gas is also discussed.