Thermaly integrated five-step ZnSI thermochemical cycle hydrogen production process using solar energy

The main target of this study is to apply thermal integration on a five-steps ZnSI thermochemical hydrogen production cycle in order to improving the process efficiency. In this process water enters the Bunsen system at a 298 K, 1 bar with flow rate of 0.5 mol/s, and CO2 is the input stream into the zinc system at 298 K and 1 bar. Oxygen and CO are output streams of Bunsen and zinc systems, respectively. Hydrogen is output of the HI system, which is obtained as a final product at 313 K, 1 bar with the flow rate of 0.5 mol/s. A solar thermal system which uses solar dish collector is applied in order to provide a portion of the required thermal load in the process. Modeling of the solar system is done through Matlab software. By using ZnSI instead of SI process, temperature of reaction decreases. Also hydrogen and carbon monoxide are produced. The results demonstrate that by this modification number of units of the Zn system reduces and the chemical process is simplified. By performing thermal integration, heat duty of the system decreases and accordingly thermal efficiency increase by 61.06%. As well as, the minimum required hot and cold utilities decrease by 51.94% and 65.52%, respectively. Solar fraction and collector thermal efficiency were obtained 42.57% and the 82% respectively. Finnaly a parametric assessment is done on the key parameters which influence performance of the process.