SnO2/SnO based redox thermochemical CO2 splitting cycle: Effect of inert gas flowrate, reduction temperature, and gas separation on the solar-to-fuel energy conversion efficiency

This paper reports the thermodynamic efficiency analysis of the SnO2/SnO redox cycle conducted using the HSC Chemistry software. A theoretical process model is developed and used, including reduction and oxidation cells, heaters, separators, and an ideal CO/O-2 fuel cell. The thermodynamic calculations are performed by varying the reduction temperature (Tred) from 1500 to 2000 K, assuming a steady gas-to-gas heat recovery effectiveness (epsilon gg) equal to 0.5, and oxidation temperature (Toxd) equal to 900 K. The obtained results indicate that as Tred increases from 1500 to 2000 K, the requirement of n?inert reduces from 17 000 to 12 mol/s, respectively. The total thermal energy demand of the cycle is significantly affected by the energy needed to heat the inert/O-2 gas mixture (from Toxd to separator-1 temperature) and inert sweep gas (from separator-1 temperature to Tred). A considerable reduction in Q?TC (by 171 500.2 kW) and Q?solar (by 189 259.6 kW) is noted due to the surge in Tred from 1500 to 2000 K. The SnO2/SnO CDS redox cycle attains the solar-to-fuel energy conversion efficiency is 16.7% at Tred of 2000 K.