Conceptual design, process integration, and optimization of a solar Cu-Cl thermochemical hydrogen production plant

A conceptual design of a solar Cu-Cl thermochemical cycle with the capacity of 6000 kg day(-1) was presented. To enhance thermal efficiency, the heat recovery within Cu-Cl thermochemical hydrogen production cycle was proposed using the pinch analysis to design a heat exchanger network that recovers heat between hot and cold streams. This improves +10.2% in the thermal efficiency of the cycle compared to previous designs. The reformed cycle was assumed to be coupled to a solar installation that provides the required thermal energy for the cycle. For further improvement, the conceptual design was considered as the base case and four optimization scenarios were conducted on that. Three objective functions, including energy efficiency, exergy efficiency and the unit cost of hydrogen were optimized in three single-objective and one multi-objective scenario. Comprehensive thermodynamic, solar thermal, and exergoeconomic models were employed to obtain objective functions. Reaction temperatures, the number of the solar collectors, and volume of the solar storage tank were selected as design variables. The best alternative to five systems (one base case and four optimized systems) were selected using the TOPSIS method. It was found that thermal efficiency-optimized system has the preference over other four systems. It had 49.83% thermal efficiency, 58.23% exergetic efficiency and 6.33 $ kg(-1) for produced hydrogen. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.