Optimization of Windows for Closed Receivers and Receiver-Reactors: Enhancement of Optical Performance.

Abstract

To reduce reflectance losses from closed receivers or chemical receiver-reactors, anti-reflection coatings, surface etching and geometrical forming of the window seem to be possible. Because of the high temperature application of these receiver types the use of antireflection (AR) coatings and etching processes on the windows are not possible at the moment. Etching can be used on borosilicate glass (Pyrex) and silicate glass, but not on quartz glass, which is needed for its high temperature resistance. The paper shows that the reflectance losses may be reduced to less than 1 percent of the incoming radiation by geometrical forming. Calculations for various shapes were carried out based on the Monte-Carlo method. With this statistical method, good approximation to the real angular flux distribution can be achieved. All shapes reach reflectance losses less than 1 %, depending on the height of the glass body.