Solar driven CdSO4/CdO thermochemical water splitting cycle for hydrogen generation

Abstract

The CdSO4/CdO thermochemical water splitting (WS) cycle was thermodynamically scrutinized by utilizing the HSC Chemistry software and the obtained results are reported in this paper. Thermodynamic equilibrium analysis was performed to identify a) the temperatures needed to initiate the thermal reduction (TR) of CdSO4 and WS reaction and b) the equilibrium molar compositions associated with both steps. The obtained results shows that an increase in the molar flowrate of Ar (n˙Ar) from 1 to 50 mol/s significantly reduced the temperature (TH) required for the complete TR of CdSO4 from 1489 to 1286 K. The efficiency analysis was carried out to estimate the various process parameters as a function of variation in the TH, n˙Ar, and WS temperature (TL). The solar-to-fuel energy conversion efficiency (ηsolar−to−fuel) of this cycle was decreased with the drop in the TH and increased with the upsurge in the TL. The maximum ηsolar−to−fuel = 46.5% was achieved when the TR and WS reactions were conducted at 1489 K and 550 K, respectively. The application of heat recuperation up to 10%, 30%, and 50% was responsible for further upturn in theηsolar−to−fuel up to 48.8%, 54.4%, and 61.3%, correspondingly.