Effects of Surface Roughness on Contact Heat Transfer between Contacting Particles

Abstract

The objective of this work is to establish a constitution equation of the contact heat transfer between colliding particles for the Discrete Element Method (DEM) simulations. Since the thermal resistance model is available to estimate the contact heat transfer, the heat transfer between two particles (spheres) was measured by changing surface roughness. The result of this is that the contact heat transfer increased as surface roughness increased. This tendency is opposite to a general one in the thermal resistance model. This would be caused by the geometric condition of the spherical contact plane. Larger surface roughness yields larger contact area. This effect would be larger than that of increasing thermal resistance. Moreover, we tried to directly observe the surface under contact condition by using a laser microscope in order to examine the surface conditions in detail. The cross-sectional profile of contacting particles was successfully detected. The macroscopic contact area calculated by considering the surface roughness well agreed with the observed one.