An empirical modification on UNIQUAC model for vapor-liquid equilibrium of refrigerant/ionic liquid mixtures

The vapor-liquid equilibrium (VLE) of refrigerant with ionic liquid (IL) is crucial for different applications, such as extractive distillation separation of refrigerant blends. In this regard, the development of accurate model to calculate the VLE of refrigerant/IL mixture is essential. In this work, the universal quasi-chemical (UNIQUAC) model was used to correlate the VLE of 25 hydrofluoroolefin(HFO)/IL and 52 hydrofluorocarbon (HFC)/IL mixtures. However, the maximum deviation between the experimental data and calculated values from the model is close to 100%. Therefore, an empirical modification on the interaction energy parameter in UNIQUAC model was proposed. Results demonstrate that the modified model exhibits greater accuracy than original model. The average absolute relative deviations between the experimental and calculated values from the modified model are lower than 3% for the studied mixtures. Furthermore, the modified UNIQUAC model was compared with other activity coefficient models including Margules, van Laar, Wilson, and NRTL model, revealing the good performance of the modified model.