Modelling and performance assessment of a thermally-driven cascade adsorption cycle suitable for cooling applications

Adsorption chillers can provide energy efficient cooling and have large potential for performance increase and cost reduction compared to conventional chillers. Among the different R&D activities currently in progress in the field, the development of advanced cascading adsorption cycles is an effective way to improve the performance of standard adsorption units, making this technology especially interesting in applications where waste heat for driving the adsorption chiller is a widely available, such as many industrial processes, cogeneration plants, I.C. engines, district heating networks. In this paper, a novel modelling tool able to simulate complex adsorption cycles is presented and validated with literature data. The simulation tool is used to investigate numerically the performance of a cascade adsorption cycle consisting of a twin adsorber high-temperature cycle with heat recovery coupled with an intermittent adsorber low-temperature cycle. A parametric analysis is carried out showing the optimization potential in terms of Coefficient Of Performance (COP) and specific cooling power (SCP) with varying cycle periods, step time ratios and adsorbent mass ratios. COP of 0.97 with SCP of 142 W/kg are found for water-zeolite 4A (high-temperature) and water-CaCl2/Silica gel (low-temperature cycle). These results are in line with previous findings reported in literature. Finally, useful recommendations for further performance improvement are provided.