Testing of a porous ceramic absorber for a volumetric air receiver

Abstract

A new absorber for a volumetric air receiver was designed, built, and tested on an existing volumetric receiver test bed (200 kW t) at the Plataforma Solar de Almeria test facility in Spain. Volumetric air receivers are currently being investigated for use in solar central receiver power plants because of their inherent simplicity. The volumetric air receiver is a unique type of solar central receiver that uses a porous absorber (heat exchanger), on which the solar energy is concentrated and absorbed within its volume. Air flows through the absorber, convectively transferring energy from the absorber to the medium. Volumetric receivers have applications in electricity production, industrial process heat, and chemical processing. We designed this new volumetric receiver absorber to use a porous ceramic material. This material was selected because of its structural strength, high-temperature capability, and the potential for using smaller pieces to build up an absorber. The ceramic absorber was tested at the Plataforma Solar de Almeria with a solar flux of up to 824 kW/m 2, and it produced outlet air temperatures of 730°C. The porous ceramic material has exhibited reasonable thermal efficiencies and excellent structural integrity in the high-flux, high-temperature solar environment. In this paper we summarize the design of and test results of the porous ceramic absorber.