Thermal contact conductance (TCC) is a key parameter, which influences the reliability of various cryogenic systems. The accurate estimation of TCC is a basic requirement for the optimal design of cryogen-free conduction cooling systems. The lack of reliable TCC results for bare demountable aluminium contacts in the sub-ambient temperature range (50–300 K) prompted us to undertake the systematic experimental investigations. A unique experimental setup has been fabricated to carryout axial heat transfer experiments, which is used for the estimation of TCC between aluminum contacts in the temperature range of 50–300 K. The influence of changing interfacial temperature (50–300 K), interfacial pressure (0.5–12 MPa), and surface roughness parameters ($\sigma$ = 1.51 to 11.06 $\mu m$), as well as the surface finishing process on TCC have been investigated systematically. The finite element (FE) rough surface contact analysis has also been carried out, and real contact area and the TCC has been estimated over the range of interfacial pressure and temperature under considerations. The real contact area was found to be less than 0.1% of the nominal area, even at 12 MPa, and it varies almost linearly with temperature and pressure. The FE estimates of TCC has shown a good agreement with experimental TCC results. Finally, an empirical correlation of TCC has been proposed by incorporating three of the functional parameters, while considering temperature-dependent thermo-mechanical properties into the analysis.

热接触电导（TCC）是关键参数，它会影响各种低温系统的可靠性。TCC的准确估算是无制冷剂传导冷却系统优化设计的基本要求。在低于环境温度范围（50–300 K）的情况下，对于可拆卸的裸露铝触点缺乏可靠的TCC结果，促使我们进行系统的实验研究。制造了一个独特的实验装置来进行轴向传热实验，该实验装置用于估算温度范围为50–300 K的铝触点之间的TCC。界面温度变化（50–300 K），界面压力的影响（0.5-12 MPa）和表面粗糙度参数（$\sigma$ = 1.51至11.06 $\mu 米$），以及对TCC的表面精加工过程进行了系统的研究。还进行了有限元（FE）粗糙表面接触分析，并在考虑界面压力和温度范围内估算了实际接触面积和TCC。发现实际接触面积即使在12 MPa时也小于标称面积的0.1％，并且几乎随温度和压力线性变化。TCC的有限元估计与实验TCC结果显示出很好的一致性。最后，在考虑到温度相关的热机械特性的同时，结合了三个功能参数，提出了TCC的经验相关性。