Global analysis of refrigerative adsorption cycles with thermal regeneration (non-uniform temperature)

Adsorption cycles with thermal regeneration are described and analysed. A cooling period is detailed and the different steps of the adsorber behaviour are described. The whole system is analysed as a combination of an adsorption cycle with non-uniform temperature in the adsorber on one hand and a heat storage process with thermal regeneration on the other. The efficiencies of these two processes have opposite dependencies on the cycle period. As a consequence, there exists an objectively optimal cycle period. Moreover, a comprehensive analysis of the process leads to the definition of two characteristic parameters: the 'global' NTU and the dimensionless outlet fluid temperature at the end of the cooling period, Theta o. The study of a very large number of optimal cycles shows that, first, the cooling COP mainly depends on the global NTU, and second, Theta o is the best parameter for specifying the optimal cycle period. In addition, the correlations between each of these two key parameters and the cycle COP give valuable information about how to design adsorbers and operate them in order to achieve a prescribed performance. (C) 1997 Elsevier Science Ltd and IIR.