ISSN Online: 2377-424X
International Heat Transfer Conference 4
SURFACE ROUGHNESS EFFECTS ON RADIANT TRANSFER BETWEEN SURFACES
Sinopsis
Radiative heat transfer between opaque interacting surfaces is formulated for equal temperature parallel plates with a one-dimensional surface roughness profile. The rough surface bidirectional reflectance and directional emittance introduced depend on material emittance, roughness element slope, and roughness element specularity. Numerical solutions to the governing integral equation for radiant intensity lead to local and total heat transfer results for a range of each of the influencing parameters. The heat transfer results demonstrate that roughness effects are relatively unimportant for high emittance materials while for low emittance materials surface roughness can change local flux by 50 percent and total heat transfer by a factor of two. Diffuse analysis employing rough surface apparent hemispherical emittance generally gave the best approximation to rough surface flux distributions although local flux errors of 50 percent were commonly observed for the low emittance material. Diffuse analysis with apparent emittance accurately predicted total heat transfer for the high emittance material, but its accuracy diminished as the material emittance decreased.