Energy and exergy analyses of a Cu-Cl cycle based integrated system for hydrogen production

This paper analyzes an integrated Cu-Cl thermochemical cycle, Kalina cycle and electrolyzer for hydrogen production. The system operating parameters such as mass fraction, pressure and temperature are varied to investigate their effects on the energy and exergy efficiencies of the with/without heat recovery and integrated system, rate of hydrogen production, and rate of oxygen production. A new Cu-Cl design layout is then presented with a heat exchanger network developed to recover heat within the Cu-Cl cycle in the most efficient manner. The exergy destruction rate in each component is determined and discussed. The results show that increasing the electrolyzer temperature is beneficial up to 328.6 K, after which the performance of the cycle results in a negative trend. The exergy efficiency varies more significantly with operating parameters than the corresponding energy efficiency. The maximum exergy destruction in the Cu-Cl cycle occurs in the first separator (16.82 kW) and in the heat exchanger of the Kalina cycle (48.05 kW), so these components should be considered for performance improvement of the system. (C) 2012 Elsevier Ltd. All rights reserved.