Cooling performance of compression-absorption cascade system with novel ternary ionic-liquid working pair

Abstract

The compression-absorption cascade system (CACS) is an efficient way to use waste heat or renewable energy. However, most of the current studies are all based on heating scenarios, and the cooling characteristics of CACS have not been reported. In terms of absorption working pairs, ionic liquids (ILs) have great potential to become alternative working fluids for absorption systems, but one of the factors restricting the large-scale application is their high price. Seeking effective strategies to reduce economic constraints while ensuring the excellent performance of IL working pairs will become a hot topic in the future. In order to overcome the application limit of ILs, a feasible strategy is proposed which the relatively cheap salt is used to replace part of the expensive IL and they are employed together as the absorbent. In this work, the vapor-liquid equilibrium data of novel IL working fluid LiBr/[EMIM][OAC]/H2O is measured experimentally, and the cooling performance of CACS with the proposed working pair is analyzed. The results show that the cooling efficiency of CACS is 0.738–0.849, which is commonly higher than traditional absorption chillers. As for comparing with reference working fluids, the novel working pair can improve the maximum performance by 1.80%–46.81%. In addition, the crystallization problem can be overcome to some extent compared with LiBr/H2O under the same absorption ability, and as for comparing with [EMIM][OAC]/H2O, the economic limitation can be alleviated. This work can be used to ease the economic limit of ILs due to the immature market right now, and give a reference for seeking a satisfactory cooling method of buildings in the context of carbon neutrality.