Influence of adsorption cycle limitations on the system performance

The economics of heat driven heat pumps are governed by two thermodynamic q uantities: the performance on the one hand and the size of the heat exchang ers, which is required to obtain this performance, on the other hand. The a im of this paper is to discuss the influence of the main features of adsorp tion cycles in comparison to absorption cycles on these quantities. In our case, a Zeolite UCC 16 x 40-type 13X has been taken as the adsorbent. The a nalysis has already been used for absorption heat pumps. In the case of ads orption and other solid sorption chillers, additional limitations appear, e .g. identical design of all adsorbers, incomplete heat recovery between ads orbers, cycling of inert mass, etc., which ali contribute to a lowering of the system performance or to an increase of the exchange area required. To show the basic differences between absorption and adsorption cycle optimiza tion, and also to show the impact of physical or technical limitations on t he adsorption chiller performance, a detailed analysis has been performed. It is confirmed that it is mainly the lack of a solution heat exchanger whi ch lowers the adsorption system COP and not physical properties of the work ing pair, so there is still a lot of room for improvement in the solid-sorp tion of heat pumps. (C) 2001 Elsevier Science Ltd and IIR. All rights reser ved.