Integration of vanadium-chlorine thermochemical cycle with a nano-particle aided solar power tower for power and hydrogen cogeneration

Abstract

The adverse environmental impacts of fossil fuels is becoming a major concern considering the climate changes. In this respect, the H2 as a carbon-free energy carrier has absorbed interest of researchers and policy makers to pay more attention to this field. In this regard, the solar energy driven frameworks are of major importance due to the abundance of solar energy as well as being a clean energy resource. However, the solar based systems suffer from lower efficiency compared to conventional fossil fuel-based systems due to large exergy destructions. One way to solve this problem and to enhance solar-based system performance is employment of nanoparticles for improving heat transfer characteristics of solar thermal loop. Present research is an attempt in this regard in which effects of employment nanofluid instead of the pure solar salt is investigated in a solar power tower system. The solar power tower unit supplies required energy to run a steam cycle for power generation and a thermochemical H2 production unit for co-generation of power and H2. Feasibility evaluations are carried out based on thermodynamic laws and exergy-based analyses as well as economic investigations are conducted to assess the system performance and multi-objective optimization is conducted to specify the optimum operation of system. A parametric evaluation is carried out to consider how design variables affect the system performance, prior to implementation of multi-objective optimization. The results have revealed positive effect of nanofluid application instead of pure solar salt and indicated enhancement of 4−5% on technical performance. In addition considering the economic investigations, the nanofluid employment bring about a reduction by around 3−4% in unit cost of product of cogeneration plant, depending on the operating conditions.