Thermodynamic analysis of an epitrochoidal rotary reactor for solar hydrogen production via a water-splitting thermochemical cycle using nonstoichiometric ceria

An epitrochoidal rotary reactor for solar hydrogen production via a water-splitting thermochemical cycle using nonstoichiometric ceria is proposed. The reactor performs solid-phase heat recovery in the form of mechanical energy via isentropic compression and expansion of the sweep gas. A thermodynamic analysis for a system consisting of the epitrochoidal rotary reactor and two exchangers is presented. Under typical conditions with a solar concentration ratio of 3000, reduction temperature of 1773K, oxidation temperature of 1073K, gas-phase heat recovery effectiveness of 0.9, mechanical energy recovery effectiveness of 0.85, and the ratio of the molar flow rates of sweep gas and ceria of 10, the solar-to-fuel efficiency is 13.2%. The thermodynamic analysis demonstrates the potential of using an epitrochoidal rotary reactor for convenient solid-phase heat recovery without sacrificing the solar-to-fuel efficiency.