Computational fluid dynamic study on the adsorption-based desalination and cooling system

Abstract

Adsorption desalination (AD) is a potentially competitive alternative for potable water production. Unlike traditional rectangular fins for finned-tube adsorbent bed in the AD system, in this study, bullet- and umbrella-shaped fins are employed in the adsorbent bed to improve the heat and mass transfer characteristics in the adsorption/desorption processes, thus augmenting the system performance. Based on a complete transient mathematical model incorporating a three-dimensional computational fluid dynamic model for adsorber and lumped models for evaporator and condenser, impacts of fin configurations regarding base diameter, tip diameter, and shape factor on system performances considering the adsorbent and the whole bed are comprehensively analyzed. Results reveal that a larger base and tip diameter with a lower shape factor contribute to specific bed productions. The underlining relationship between fin configurations and overall performance (total daily water production, total cooling power, and coefficient of performance) is further explored via machine learning. And the optimal fin shape is identified by the genetic algorithm. The optimal base diameter, tip diameter, and shape factor are 0.262, 0.517, and 4.20, respectively, which render a total water production of 5.20 m3/day with a total cooling power of 0.149 kW and coefficient of performance of 0.855.