Numerical investigations of a continuous thermochemical heat storage reactor
Résumé
Thermochemical systems are a good alternative to current technologies for long-term heat storage since the energy is stored as a chemical potential and there is no heat-loss during the storage phase. Nowadays, a large number of studies have been carried out on the development of integrated thermochemical reactor and much less studies have investigated the separated reactor technologies. These lasts present the advantage, among others, to dissociate the thermal power and the storage capacity of the system which also increases the storage density of the process. This paper investigates the functioning of an open continuous thermochemical reactor with falling solid flow and humid air cross-flow. A 2D model has been developed and set up with the finite element simulation software COMSOL Multiphysics to bring out heat and mass transfers phenomena in the reactor. This study focuses on the influence of inlet pressure and vapour fraction of the air on the reaction behaviour and the reactor performances (power, temperature). This study looks also into the influence of the reaction front on the pressure drop in the reactor. It has been highlighted the presence of a sharp reaction front between one part of the reactor (bottom) where the solid is completely hydrated and the other part (top) where the solid has not yet reacted, this sharp front is strongly dependant of the inlet air conditions. Also, there is an inertial phenomenon at the entrance of the unreacted solid which is influenced by inlet air pressure and creates a particular air velocity field.