Control of Radiation Heat Transfer from Solid Surface Using Grating Composed of Parallel Elliptical Cylinders : Energy Concentration in Direction Normal to Solid Surface

Abstract

A specially designed grating is applicable to directional control of radiation heat transfer from a heated surface. In this paper, a study of radiation heat transfer control using a grating composed of elliptical cylinders (GEC) is described. An analysis of radiation heat transfer is performed for a physical model in which the grating of circular cylinders (GCC) of our previous study are replaced by the GEC and the major or minor axes of the elliptical cylinders are set vertically to the heated base surface. Numerical solutions are obtained. The apparent hemispherical emissivity and the limiting angle expressing the degree of radiation energy concentration are calculated for geometrical parameters, e. g., ratio of the major axis to the minor axis and center-to-center distance of cylinders. It is found that the GEC has even better characteristics for the control of radiation heat transfer, compared with the GCC, especially for apparent hemispherical emissivity, i. e., the heat-transfer rate.