Achievement

A novel solar-thermochemical reactor for the reduction of ZnO powder using concentrated sunlight has been designed, constructed and tested. The purpose of the reactor is to accomplish the first step in a two-step water-splitting process to generate hydrogen renewably from sunlight using the ZnO redox cycle. Abbreviated as GRAFSTRR (Gravity-Fed Solar-Thermochemical Receiver/Reactor), the reactor is closed to the atmosphere, and features an inverted conical-shaped reaction surface along which reactant powder descends continuously as a moving bed, undergoing a thermochemical reaction at high temperature upon exposure to highly concentrated sunlight within the reaction cavity. Heat transfer and Zn production within the cavity have been modeled.

Koepf E., Advani S. G., Steinfeld A., and Prasad A. K. A novel beam-down, gravity-fed, solar thermochemical receiver/reactor for direct solid particle decomposition: Design, modeling, and experimentation. Hydrogen Energy, 37, 16871–16887 (2012).