title: Experimental Demonstration of the Thermochemical Reduction of Ceria in a Solar Aerosol Reactor.
abstract: We report on the experimental demonstration of an aerosol solar reactor for the thermal reduction of ceria, as part of a thermochemical redox cycle for splitting H2O and CO2. The concept utilizes a cavity-receiver enclosing an array of alumina tubes, each containing a downward gravity-driven aerosol flow of ceria particles countercurrent to an inert sweep gas flow for intrinsic separation of reduced ceria and oxygen. A 2 kWthlab-scale prototype with a single tube was tested under radiative fluxes approaching 4000 suns, yielding reaction extents of up to 53% of the thermodynamic equilibrium at 1919 K within residence times below 1 s. Upon thermal redox cycling, fresh primary particles of 2.44 μm mean size initially formed large agglomerates of 1000 μm mean size, then sintered into stable particles of 150 μm mean size. The reaction extent was primarily limited by heat transfer for large particles/agglomerates (mean size > 200 μm) and by the gas phase advection of product O2for smaller particles.
authors.affiliation: Department of Mechanical and Process Engineering, ETH Zürich , 8092 Zürich, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Welte
authors.affiliation: Department of Mechanical and Process Engineering, ETH Zürich , 8092 Zürich, Switzerland.
authors.forename: Rafik
authors.initials: R
authors.lastname: Barhoumi
authors.affiliation: Department of Mechanical and Process Engineering, ETH Zürich , 8092 Zürich, Switzerland.
authors.forename: Adrian
authors.initials: A
authors.lastname: Zbinden
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Florida , Gainesville, Florida 32611-6250, United States.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Scheffe
authors.affiliation: Department of Mechanical and Process Engineering, ETH Zürich , 8092 Zürich, Switzerland.
authors.forename: Aldo
authors.initials: A
authors.lastname: Steinfeld