A transient method for the experimental evaluation of interface heat transfer coefficients at different contact pressures: The case of aluminum and copper interplay

In most of the thermal engineering applications, where heat is transferred by conduction between two different objects, the contact resistance or the contact heat transfer coefficient plays a major role. The conductivity of materials as well as the surface roughness strongly affect heat transfer in ways that makes challenging a proper estimation of the contact resistance. Despite the efforts, literature lacks in the definition of a simplified method for an immediate evaluation of the contact resistance. This work presents an experimental method to measure the interface heat transfer coefficient between two fiat metallic surfaces. The method is based on a one-dimensional transient model relying on the time-temperature trends of two cylinders, initially at different temperatures, placed in contact. An uncertainty analysis is carried out to assess the reliability of the method proposed. Experimental tests have been conducted using aluminum-copper coupling, a common contact material solution in heat exchangers and battery packs. Results of the experimental campaign showed that the method is effective and that it allows to correlate the interface heat transfer coefficient to the contact pressure.