Thermodynamic Properties of Ternary Ionic Liquids as New Working Pairs for Absorption Heat Transformer

In response to increasing energy demands, absorption heat transformers (AHTs) have been widely employed as efficient energy conversion devices across various fields. However, existing working pairs (e.g., LiBr/H 2 O and NH 3 /H 2 O) exhibit high corrosiveness and limited thermal stability, significantly restricting their applicability in high-temperature environments. Therefore, the development of high-performance working pairs is crucial for improving the efficiency and stability of AHT systems. In this study, four groups of ionic liquid-based ternary matrix pairs: LiBr-[EMIM]Cl/H 2 O (1:2), LiBr-[EMIM]Cl/H 2 O (1:3), LiBr-[EMIM][DEP]/H 2 O (1:3), and LiBr-[EMIM][DMP]/H 2 O (1:3), were systematically evaluated through short-term corrosion experiments. The effects of corrosiveness, thermal stability, density, viscosity, and specific heat capacity were analyzed. Experimental results and data analysis clarified the high-temperature properties of ionic liquids, while thermogravimetric analysis and viscosity measurements were conducted to evaluate the relative merits of different working pairs. Results indicate that the LiBr-[EMIM]Cl/H 2 O (1:2) system exhibits the lowest corrosiveness and good thermal stability, making it suitable for corrosion-sensitive AHT systems, while the LiBr-[EMIM][DMP]/H 2 O (1:3) system demonstrates optimal thermal stability at high temperatures, rendering it a complementary solution for high-temperature applications. This study establishes an experimental basis for optimizing AHT working pairs and provides essential data to inform their selection in AHT systems.