Control of Radiation Heat Transfer from Solid Surface by a Grating of Parallel Circular Cylinders.

Abstract

Radiation heat transfer from a solid plane surface is directionally controllable by means of a grating composed of circular cylinders. An analysis of the radiation heat transfer is made for a physical model in which a grating of parallel cylinders is placed in front of a black heat-transfer surface, and the cylinder surfaces have both specular and diffuse reflectivity components ( ρc=ρsc+ρdc). Numerical solutions are obtained. The apparent directional emissivities and the limiting angles expressing a degree of energy concentration are calculated for parameters such as ρsc/ρc and center-to-center distance of cylinders. It is clarified that the grating of cylinders is useful for concentrating the radiation energy emitted from the heat-transfer surface in the direction normal to the grating surface.