Experimental and Theoretical Studies on Thermal Contact Resistances for Flat Convex Rough Surfaces between Two Aluminum Rods

Abstract

Experimental and theoretical studies were conducted to investigate the thermal contact resistances (TCRs) between two aluminum rods. One pair of aluminum rods each having a flat rough surface and four pairs of aluminum rods each having a flat convex rough surface were used as specimens. The flat convex rough surface was composed of a contact and a noncontact surface, and the specimens were prepared by changing radius and height of the contact surface. In experiments, after a prescribed pressure was loaded on a pair of the aluminum rods, the top of the upper rod was heated by a film heater while the bottom of the lower rod was cooled using a cooling block. The TCR between the two rods was evaluated from steady-state temperature distributions in the rods. The experimental results of the TCR for the flat rough surfaces were compared with the calculated values by Sanokawa’s equation. Based on a concept of analogy between an electric and a thermal resistance network, two simple equations to evaluate the TCR for the flat convex rough surfaces were derived. These two equations were obtained by dividing the physical model perpendicular (Case I) and parallel (Case II) to the heat flow direction. The simple equation of Case I was moreover modified to consider the influence of the constriction/spreading resistance in the rods, and its validity was confirmed by comparing the calculated values with the experimental results.