Theoretical model of thermal contact conductance considering electron and phonon conduction in broad temperatures

This study presents a thermal contact conductance (TCC) model that improves predictive accuracy across a wide temperature range, particularly in the region above the peak in thermal conductivity. In conduction cooled cryogenic systems that include current leads or resistive thermal components, heat is generated internally or transferred from external sources, requiring accurate estimation of TCC. Copper, a commonly used thermal conductor in such systems, exhibits nonlinear thermal conductivity with temperature, which makes precise prediction of TCC challenging, especially near and beyond the conductivity peak. The proposed model builds upon the Cooper-Mikic-Yovanovich (CMY) formulation by incorporating mechanical contact parameters along with thermophysical influences, such as size effects and heat carrier behaviour, through a modified thermal conductivity expression. The model was assessed using previously reported experimental data for oxygen-free high conductivity copper interfaces. Compared to conventional approaches, it demonstrates a significant reduction in deviation from measured values across the full temperature range, with improved agreement in the post-peak region of thermal conductivity.