Optimization of UNIQUAC interaction parameters for absorption refrigeration machine working fluids

The choice of the most appropriate thermodynamic model for the prediction or calculation of thermodynamic properties is a crucial task. Consequently the present study deals with the determination of excess properties for refrigerant mixtures which are required for the calculation of the various involved enthalpies and hence the used refrigeration machine. The present study considered just as a sample system the pair R124 (2-chloro-1, 1, 1, 2-tétrafluoroethane)-DMAC (N, N'-Dimethylacetamide) — by calculating the molecular interaction parameters for the UNIQUAC model using the excess enthalpy of mixing at eight different varying from 0°C to 140°C by a step of 20°C. The obtained interaction parameters values led to mixing excess enthalpy results very close to experimental values, contrary to the UNIFAC model which showed huge deviations. Therefore the optimization technique based on the Simplex method proved to be very reliable in the determination of interaction parameters for the UNIQUAC.