An improved thermal contact resistance model for pressed contacts and its application analysis of bonded joints

Contact heat transfer across mechanically pressed solid/solid contacts with or without interstitial bonding material is an important phenomenon in cryogenic engineering. This paper introduces an improved thermal contact resistance (TCR) model. The model, which considers both plastic and elastic deformation, matches well with the experimental data for pressed stainless steel 304 contacts in the range 110-150 K and 1-7 MPa. A method is also suggested to evaluate the microscopic effects of the TCR for alloyed metals in the range between liquid nitrogen temperature and room temperature. Based on the improved TCR model and the analysis of the heat transfer across the bonded joints, the thermal joint resistance (TJR) is modeled as the sum of the TCR and the bonding material resistance. The solid/liquid contact resistance is obtained by assuming the ideal gas law holds for the trapped air in the micro gaps. The TJR model indicates that the TJR depends on the bonding area, the bond line thickness, thermal conductivity of the bonding material, the initially applied pressure, the surface roughness, and thermal resistance of the bare contacts. The TJR model predictions are in good agreement with experimental data for joints incorporating bonding materials or thermal greases.