Supercritical CO_2 Brayton Cycle Coupled with a Sodium Fast Reactor: Na/CO_2 interaction experiments and modeling

摘要

The Supercritical CO_2 Brayton Cycle could be a promising option to enhance the competitiveness of future Sodium Fast Reactor due to its high thermodynamic efficiency and turbine compactness. Furthermore, it may suppress the difficulties related to the sodium/water reaction. Nevertheless, it is highly necessary to get thermodynamic and kinetics information on the potential sodium/CO_2 chemical interaction and its potential consequences, to compare both of the systems. Kinetics chemical interactions were investigated via calorimetric techniques as Accelerating Rate Calorimetry which gave preliminary information on the reaction orders and via the theoretical and experimental study of a biphasic reactive jet of CO_2 into sodium. A theoretical model was built to describe jets of CO_2 into sodium to simulate a leak in a tube heat exchanger between the sodium coolant and the energy conversion fluid. Kinetics parameters are introduced in the model and have to be identified comparing theoretical and experimental data as temperature distribution within a jet of CO_2 into sodium. An experimental bench was designed and built in CEA to enable the realization of reactive gas jets in liquid sodium and to allow by identification, the determination of kinetics parameters for Na-CO_2 reaction.