Second law analysis of a novel cycle concept for adsorption heat pumps.

In this paper, a second law analysis of a novel adsorption cycle concept is presented. The entropy production of the cycle concept “Stratisorp” is quantified and divided among components and half cycles. The goal of the Stratisorp cycle is to improve the internal heat recovery by utilizing an integrated stratified thermal storage: heat recovery of both sensible and sorptive heat is crucial for the efficiency of most thermodynamic adsorption cycles. The cycle concept is appropriate for both adsorption chillers and heat pumps. In its simplest configuration, it requires a single adsorber only. In performing this thermodynamic analysis, the cycle itself and the system design are assessed and potential improvements are shown. The authors analyze the theoretical limits of the Stratisorp cycle concept, investigate on how much heat is recoverable in practice by doing transient simulations, and compare the resulting COP to the corresponding Carnot efficiencies, computed via entropic mean temperatures. Entropy production due to finite driving temperature differences, due to non-isothermal heat transfer both to and from the adsorber and the storage and due to storage losses are addressed separately.