Optical Analysis of a Novel Solar Thermochemical System with a Rotating Tower Reflector and a Receiver–Reactor Array

We propose a novel concept of a rotating tower reflector (TR) in a beam-down optical system to alternate concentrated solar irradiation of an array of solar receiver–reactors realizing multi-step solar thermochemical redox cycles. Heat recovery can be implemented in the receiver–reactor array, which is reported to result in dramatically improved thermal-to-chemical efficiency of receiver–reactors. Here, optical and radiative characteristics of the proposed optical system are explored analytically and by Monte-Carlo ray-tracing simulations.

We study the effects of system geometrical and optical parameters on the optical and radiative performance. TR axis is required to be tilted for accommodating the receiver–reactor array, resulting in reduced optical efficiency. We demonstrate that the annual optical efficiency of a baseline system with the receiver–reactor located south of the tower decreases from 46% to 37% for the axis tilt angle of TR increasing from 2° to 20°. Locating the receiver–reactor array south of and as close as possible to the tower offers the most promising optical configuration. The optical analysis conducted in this study provides a general formulation to enable predictions of thermal-to-chemical efficiency of the receiver–reactor array and overall solar-to-chemical efficiency of the solar thermochemical plant.