Directional Control of Radiation Heat Transfer by V-Groove Cavities-Collimation of Energy in Direction Normal to Cavity Opening

for the case of p 0 = 0. The rays striking the emitter surface may cause the temperature increase, and may damage the heater surface. The heater is not damaged for the involute reflector because the emitted rays are not absorbed by the emitter. Comparison With Experimental Data. The experimental data for involute and circular arc reflectors show relatively good accordance. Especially the values in the vicinity of the aperture edges of IR agreed; nevertheless, the directional reflectivity of the aluminum was derived from the theoretical value for X = 0.5 ^m. In the experimental data, there are several parts that are smaller than the theoretical prediction. This is due to the fact that the directional radiant intensity on the surface of the fluorescent lamp is not ideally uniform, but is of a smaller value at large emission angle 9; hence, the effect results in a lower value of experimental data than the prediction. For practical application of the involute reflector, some deformation of the involute may be needed for improving the effect of unisotropic emission characteristics of the emitter surface