Parametric analysis of membrane-based absorbers at air-cooling thermal conditions

Continued improvements in the design and configuration of the absorber have been suggested to reduce its size for utilization in small scale applications. Use of membrane contactors in the form of hollow fiber membrane module or plate-and-frame membrane module is one of the alternatives to achieve compact absorbers. Most of the research in absorption cooling systems is done using the conventional working fluid mixtures, water/LiBr and ammonia-water with water as a cooling medium. Moreover, there is a growing interest for air-cooled absorption chillers, for which water/(LiBr + LiI + LiNO₃ + LiCl) mixture is proposed as working fluid due to its larger range of solubility. In this study, numerical analyses are performed to evaluate the performance of a plate-and-frame membrane based absorber both with water/LiBr and water/(LiBr + LiI + LiNO₃ + LiCl) at air-cooled conditions. Results shows that a 25% increase in the absorption rate can be achieved utilizing water/(LiBr+LiI+LiNO₃+LiCl) working fluid mixture when compared to water/LiBr at air cooled conditions without crystallization problems.