Prediction of heat transfer phenomena and resulting temperature distributions is crucial among many appliances in the industry sector. In a vacuum, the dominant mode of heat transfer is conduction. The resulting temperature drop at the body’s interface is dependent on a parameter known as Thermal Contact Conductance (TCC) or, alternatively, Thermal Contact Resistance (TCR). During the literature study, it was found that several parameters are mainly affecting the heat transfer performance between the samples: surface roughness, contact pressure, material properties, and environmental conditions. The Thesis project is accomplished in cooperation with Philips Engineering Solutions (PES). For the Thesis, it is proposed to explore the TCC phenomenon through a combined study. The first part is investigating newly manufactured samples with a modified experimental setup in vacuum conditions. Before the Main Test Campaign started, the experimental setup and old laboratory samples were tested to mark the way. Also, several more samples were tested alongside the Main Tests to extend the TCC database. Another important study goal is to perform thorough surface analysis using a Digital Microscope. The analysis results in a surface roughness evolution study and reconstruction of the surfaces using MATLAB © software. The surfaces are then matched together to simulate and predict the parameter known as the real contact area. The study ends with a section summarizing the investigation and proposing recommendations and possible further research.

This thesis aims to investigate the effects of contact pressure and type of deformations on the thermal contact conductance(h’) for dry metal-metal contacts. Also, an attempt is made to develope a thermal contact conductance estimation model for the same. The materials used in this thesis are metals (aluminium and tin). Several experiments are performed on two different test setups. The first setup is situated in the process and energy department[P&E] of TU Delft where tin material is used to investigate deformation effects on h’ with respect to contact pressure ranging till 4MPa. The sample is in a shape of a wire with a diameter 2mm and placed between two copper cylinders for evaluating h’. The second setup is situated in Philips Engineering Solutions [PES] where flat aluminium samples are used with different roughness under high contact pressures (up to 25MPa). Later, the results from both experimental setups are compared to the prediction from literature models to brief their general applicability. The increase in contact pressure over a surface roughness, first deforms a surface elastically and then plastically. Plastic deformation increases the actual contact area and conducts more heat than elastic with sample contact pressure.
Oxide layer formation over time is critical for aluminium surfaces and so aging may cause differences in contact conduction. In conclusion, there is a large difference between the experimental results and prediction by literature models. Only when a lot of effort is put in keeping orientation exactly the same, reproducibility is good, rest the thermal contact conduction is irreproducible. The development of an entirely new semi-empirical model is very complex. There is a need to be aware of validity ranges of thermal contact conductance literature models as they quickly deteriorate outside their application ranges and the usage of available models should be done critically. The real contact area plays a major role in estimating h’.