Waste heat driven adsorption (AD) cycle has been employed in the industries for cooling and desalination because of their simple operation and low OPEX. In conventional AD cycle, the granular adsorbent are packed in the form of cake in heat exchangers, results larger foot print and lower performance due to poor heat transfer from heat source to adsorbent. The heat transfer rate of an adsorbent embedded heat exchanger can be significantly improved by using powder adsorbent coated by binder on the fin surfaces of exchangers. This work will evaluate the performance of adsorbent coated heat exchanger adsorption cycle. We focuses on a common adsorbent-adsorbate pair utilized in the AD cycle, i.e. silica gel-water and hydroxyethyl cellulose (HEC) binder. We presented that overall heat transfer coefficient can be improved to almost two folds by coating techniques as calculated experimentally. We also showed that binder have minimal effect on pore surface area of binder. We developed detailed mathematical model to simulate, using FORTRAN, adsorbent coated bed AD cycle performance and to compare it with conventional cycle. The results showed that, advance adsorbent coating technique can improve AD cycle performance to two folds as compared to conventional granular packed bed technology. With coated bed AD cycle, system can produce double the amount of desalinated water or cooling effect with same amount of waste heat available.
Keywords: Adsorption cycle, Adsorbent coating, heat transfer, mass transfer, Overall heat transfer coefficient.
Dr. Wakil is working on thermal systems for cooling and desalination and their hybridization (Multi-effect Desalination, Absorption Chiller, Adsorption Chiller and Desiccant Dehumidifier) for overall system performance improvements. He is also working on heat transfer improvement specially for falling film evaporators at low temperature operation (<50C). He developed a correlation for falling film heat transfer coefficient. He is also working on economic analysis of single and hybrid systems. He developed a model for primary fuel cost apportionment in dual-purpose plants based on exergy analysis. He is also involves, system design, P & ID and P & FD development, system installation and its integration. He also has expertise on complex system modelling and simulation.