A high-pressure window for volumetric solar receivers

The absorbing matrix of a volumetric (directly irradiated) solar receiver must be exposed to the concentrated incoming sunlight. Most applications require that the receiver operates at an elevated pressure and in many cases the working fluid is not air. These requirements can be met only if the receiver is equipped with a transparent window. A novel frustum-like high-pressure (FLHiP) window, made of fused silica, is presented. Optical, mechanical, and thermal analyses, over 1,000 hours of accelerated life-time tests and several hundred hours of tests in a solar receiver, show that this window satisfies the required criteria for operation in a volumetric solar receiver, whose operating pressure and peak absorber temperature reach 30 bar and 1700 degrees C, respectively.