Assessment of solid heat recovery strategies for solar thermochemical cycles – Proposal of a new particle based solid heat recovery concept

Abstract

The most advanced solar thermochemical cycles in terms of demonstrated reactor efficiencies are based on temperature swing operated receiver-reactors with open porous ceria foams as redox material. The demonstrated efficiencies are encouraging but especially for cycles based on ceria as redox material studies have pointed out the importance for high solid heat recovery rates to reach competitive process efficiencies. Different concepts for solid heat recovery have been proposed mainly for other types of reactors and demonstration campaigns have shown first advances. Still, solid heat recovery remains an unsolved challenge. In this study chances and limitations for solid heat recovery using a thermal storage unit with gas as heat transfer fluid are assessed. A numerical model for the reactor is presented and used to analyze the performance of a storage unit coupled to the reactor. The results show that such a concept could decrease the solar energy demand by up to 40% and should be further investigated.