Performance assessment of a combined system to link a supercritical water-cooled nuclear reactor and a thermochemical water splitting cycle for hydrogen production

Abstract

In this paper, a high-temperature chemical heat pump, which employs the reversible catalytic methane conversion reaction, is proposed. The reaction shift from exothermic to endothermic and back is achieved by changing the steam concentration in the reaction mixture. This heat pump, coupled with the second steam cycle of a supercritical water (SCW) nuclear power plant on one side and a thermochemical water-splitting cycle on the other, permits the transmission of some part of the heat generated in the first steam cycle to a higher temperature level in order to transfer it into the water-splitting cycle. A comparative performance assessment through thermal and hydrogen production efficiencies are conducted of the combined system comprising a SCW nuclear power plant and a chemical heat pump, which provides high-temperature heat to a thermochemical water-splitting cycle for hydrogen production. It is concluded that the proposed chemical heat pump permits the utilization efficiency of nuclear energy to be improved by at least by 2% without jeopardizing nuclear reactor safety. The influence of the steam/methane ratio in the heat pump working medium on the efficiency of the pump is investigated. Based on this analysis, further research appears to be merited on the proposed design of a nuclear power generation plant combined with a chemical heat pump, and implementation in appropriate applications seems worthwhile.