Analysis and optimization of the cyclic working mode of thermochemical transformers

Thermochemical processes present a cyclic working mode: they combine two ac tive phases separated by intermediate phases. An important scientific probl em is linked to the management of this cyclic working. The relevant perform ance 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 parameter s: the advancement reached in synthesis, the equilibrium drop, and a parame ter 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 rea ctive media. With this model, the objective is to define in st reference ca se the working mode leading to an optimum value of the criteria combining t he relevant performances. From these results, the influence of transfer par ameters on the previous optimum values is analyzed in order to define the e xtreme cases. (C) 2000 Elsevier Science Ltd. All rights reserved.