Development of models for prediction of solubility for HFC working fluids in pentaerythritol ester compressor oils

This study aims to further develop a model of the group contribution type t hat can predict the solubility of mixtures of HFC working fluids and pentae rythritol ester compressor oils. The investigation is based on solubility d ata for 20 systems of five different HFCs in foul different pentaerythritol esters. First, five different activity factor-based thermodynamic models w ere investigated to determine to what extent they call describe the solubil ity data. Two promising models were selected and extended with group contri bution parameters to be able to predict solubility data. The first model, a modified Flory-Huggins based predictive model (termed MFH), needs only 15 general parameters to describe the data with a relative deviation of loss t han 3.4%. The second model, a predictive Unifac model with an extended temp erature dependence, needs 33 general parameters to describe the solubility data for the 20 systems with a relative deviation of less than 3.5%. (C) 20 00 Elsevier Science Ltd and IIR. All rights reserved.