Application of chromium oxide-based redox reactions for hydrogen production via solar thermochemical splitting of water

Thermodynamic equilibrium, as well as efficiency analysis of the Cr₂O₃/Cr water splitting (Cr-WS) cycle, was conducted in this study. The thermodynamic properties required for the computations were obtained from an HSC Chemistry 9.9 software. An increase in thermal reduction (TR) temperature (T_H) from 1800 K to 2230 K was responsible for the rise in the percentage TR of Cr₂O₃ (Tr-Cr) from 0% to 100%. The equilibrium analysis additionally indicates that the re-oxidation of Cr into Cr₂O₃ via WS reaction is feasible at any temperature from 300 to 3000 K (we have selected 1300 K for this study). The efficiency analysis indicates that the Q_{solar-reactor-Cr-WS} and Q_{solar-heater-Cr-WS} were enhanced by 3636.8 kW and 260.0 kW due to the increment in the TH from 1800 K to 2230 K. The increase in the Q_{solar-reactor-Cr-WS} and Q_{solar-heater-Cr-WS} resulted into a rise in the Q_{solar-cycle-Cr-WS} by 3896.8 kW. The_{ηsolar to fuel Cr WS}increased from 9.5% to 26.4% when the T_H was augmented from 1800 K to 2000 K. A further rise in the T_H from 2000 K to 2230 K resulted in a reduction in the_{ηsolar to fuel Cr WS} from 26.4% to 21.3%. After employing the 100% heat recuperation, the_{ηsolar to fuel HR Cr WS of the Cr-WS} cycle was improved up to 48.3% at T_H = 2000 K.

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Published in: Fuel
License: http://creativecommons.org/licenses/by/4.0/
See article on publisher's website: https://dx.doi.org/10.1016/j.fuel.2020.118160