Refrigerants design for an absorption refrigeration machine using group contribution methods

The use of the group contribution concept in the design of refrigerants for a single effect absorption refrigeration machine is presented. Chosen functional groups were combined according to the known chemistry rules to generate refrigerant candidates. The prediction of vapor-liquid phase equilibria data using the UNIFAC (Universal Functional Activity Coefficient) model and the Peng-Robinson equation of state and the resolution of heat and mass balances over different compartments led to the coefficient of performance (COP). An exergy analysis was carried out in order to assess the performance of the machine by calculating the exergy efficiency, the second law efficiency and the exergy destruction ratio. The design strategy was tested with chosen groups such as Fluor (F) and Methyl (CH3), Carbon (C), Methine (CH) and Methylene (CH2) and with N, N Dimethylformamide (DMF) as the absorbent. The results showed Interesting refrigerant-absorbent pairs with reasonably high COP values.