Investigation and assessment of the integrated copper chlorine cycle for hydrogen production with a new separation process

Abstract

The production of hydrogen as a clean fuel is anticipated to have a major impact on the development of the environmentally benign generation of energy. At present, a significant portion of hydrogen generation is based on the exploitation of fossil fuels thereby contributing to an increase in global greenhouse gas emissions. Thus, hydrogen production through non-fossil fuel sources is essential for sustainable development. In this thesis, green hydrogen generation is considered via a four-step copper-chlorine thermochemical water-splitting cycle. The lab-scale integrated copper-chlorine cycle at the Clean Energy Research Laboratory is investigated in this regard. The integrated cycle is comprehensively studied through the energy and exergy, thermal management, exergoeconomic, exergoenvironmental, and multi-objective optimization approaches for performance assessment. A new approach for the anolyte separation step of the integrated cycle is also investigated and the flash vaporization process is proposed as a feasible option in this regard. The integrated cycle is also conceptually modified with the flash vaporization process and investigated through the energy and exergy, thermal management, exergoeconomic, and exergoenvironmental approaches and the performances of the integrated cycle at the Clean Energy Research Laboratory and the cycle conceptually modified with the flash vaporization process are comparatively assessed as well. Moreover, a standalone experimental setup is developed and the flash vaporization process is experimentally investigated. The overall energy and exergy efficiencies of the integrated cycle are evaluated as 6.6 and 10.2%, respectively while those of the cycle conceptually modified with flash vaporization are evaluated as 7.2 and 11%, respectively. The average unit hydrogen cost for the integrated cycle is evaluated to be 4.94 $/kg while that for the conceptually modified cycle is 4.7 $/kg. Moreover, the average unit hydrogen cost for the modified cycle with the incorporation of waste heat recovery is evaluated to be 2 $/kg for a production capacity of 1.3 T/h. In the context of the experimental assessment of the flash vaporization process, the flash chamber design with a higher length-to-diameter ratio results in a higher volume of the separated species.