Prediction and performance evaluation of low-GWP refrigerant/organic solvent working pairs in absorption refrigeration system

Global warming presents a critical environmental challenge, making the search for environmentally friendly refrigerants research focus. In this study, over 60 low-GWP refrigerant/organic solvent working pairs used in absorption refrigeration cycle (ARC) are predicted and evaluated. The vapor-liquid phase equilibrium (VLE) of these working pairs is predicted using the UNIFAC-DMD model, while the excess properties such as excess Gibbs free energy (GE), excess enthalpy (HE), and excess entropy (SE) are calculated to evaluate their performance in ARC. The intermolecular interaction forces are analyzed from the perspective of molecular polarity to explain the phenomena observed in the excess properties. The relationship between excess properties and ARC performance, including the coefficient of performance (COP), solution circulating ratio, and mass fraction difference, is investigated. The results show that the GE and HE of almost all working pairs containing low-polarity refrigerant hydrocarbons are greater than 0, while the working pairs containing high-polarity hydrofluoroolefins have more than half GE and HE less than 0, and have smaller SE. Its COP is 2–4 times higher than that of hydrocarbon. Four criteria for evaluating ARC performance of working pairs are summarized. Additionally, the characteristics of sensible heat have additional effects on the basis of the evaluation criteria.