Analysis and optimization of the cyclic working mode of thermochemical transformers

Thermochemical processes present a cyclic working mode: they combine two active phases separated by intermediate phases. An important scientific problem is linked to the management of this cyclic working. The relevant performance depends on the application: mean power of cold or heat production over a whole cycle, total amount of energy stored, duration of productive phase… These performances evolve in opposite way and depend on three parameters: the advancement reached in synthesis, the equilibrium drop, and a parameter that characterizes the end of an intermediate phase. A model has been developed to simulate this cycle working mode. It couples for each phase the solid–gas kinetics and heat and mass transfer in the reactive media. With this model, the objective is to define in a reference case the working mode leading to an optimum value of the criteria combining the relevant performances. From these results, the influence of transfer parameters on the previous optimum values is analyzed in order to define the extreme cases.