Ionic liquid based absorption chillers for usage of low grade waste heat in industry

Abstract

The standard working pairs for absorption chillers, ammonia/water and water/lithium bromide show problematic behaviours like crystallisation and corrosiveness. Because of their convenient solving properties and their low vapour pressure, ionic liquids are a new promising class of sorbents for absorption cooling purposes. In this study, the working pairs water/1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) and water/1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM][DMP]) are implemented in AspenPlus. The performance of a single effect cycle with these pairs is simulated and compared to results of a cycle with water/LiBr. For [EMIM][DMP] a coefficient of performance (COP) comparable to that of LiBr or even higher (up to 0.85) is found. [MMIM][DMP] shows a smaller maximum COP but a largely wider operating temperature range than LiBr. Results are compared with those of other groups, discrepancies discussed and improvements suggested. Copyright © 2013 John Wiley & Sons, Ltd.