Thermal efficiency evaluation of a ZnSI thermochemical cycle for CO2 conversion and H2 production - Complete system

In this paper, a flowsheet of a zinc-sulfur-iodine (ZnSI) thermochemical cycle is designed. The mass and heat balance are presented. Thermal efficiency is chosen as the evaluation criterion of the whole system, and the effects of three operating parameters (composition of the Bunsen reaction products, ZnI2 decomposition ratio, and hydroiodic acid concentration in ZnO-HI reaction) are also investigated. Results show that ZnI2 decomposition ratio and HI concentration in ZnO-HI reaction have little influence on the whole system, while optimizing the Bunsen reaction to obtain a high HI concentration in the over-azeotropic HI solution is effective to increase thermal efficiency. However, high ZnI2 decomposition ratio and HI concentration in ZnO-HI reaction would cut the complexity of the process and benefit the system. Moreover, thermal efficiency could exceed 40% under proper operating conditions.