Search

This study aims to further develop a model of the group contribution type that can predict the solubility of mixtures of HFC working fluids and pentaerythritol ester compressor oils. The investigation is based on solubility data for 20 systems of five different HFCs in four different pentaerythritol esters. First, five different activity factor-based thermodynamic models were investigated to determine to what extent they can describe the solubility data. Two promising models were selected and extended with group contribution 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 less than 3.4%. The second model, a predictive Unifac model with an extended temperature dependence, needs 33 general parameters to describe the solubility data for the 20 systems with a relative deviation of less than 3.5%.

Solubilities of five different hydrofluorocarbons (HFCs) in a pentaerythritol tetrapentanoate ester (95% purity) have been measured at temperatures between 303.15 and 363.15 K and pressures between...

The solubility of 1, 1, 1, 2,2-pentafluoroethane (HFC125), 1, 1, 1, 2-tetrafluoroethane (HFC134a), 1, 1, 1-trifluoroethane (HFC143a) and 1,1-difluoroethane (HFC152a) in four well-known hydrocarbons have been measured at temperatures between 293.15 and 363.15 K and pressures between 0.05 and 2 MPa. Henry's constant, and the activity coefficient for HFCs at infinite dilution, have been derived for measurements below 0.28 MPa. The measurements were made with an isochoric method and their uncertainty is less than 2% for Henry's constant and less than 3% at high pressure. For several mixtures, the experimental data have been correlated with the UNIQUAC method and binary interaction parameters have been derived, resulting in a deviation from the data of less than 4%. La solubilite de 1, 1, 1, 2, 2-pentafluoroethane (HFC125), de 1, 1, 1, 2-tetrafluorethane (HFC134a), de 1, 1, 1-trifluoroethane (HFC143a) et de 1, 1-difluorethane (HFC152a) dans quatre hydrocarbures bien connus a ete mesuree e des temperatures entre 293,15 et 363,15 K et des pressions entre 0,05 et 2 MPa. La constante de Henry et le coefficient d'activite pour les HFC e une dilution infinie ont ete calcules pour les mesures effectuees en-dessous de 0,28 MPa. Les mesures ont ete realisees avec une methode isovolumique et leur incertitude est inferieure e 2% pour la constante de Henry et inferieure e 3% e une pression elevee. Pour plusieurs melanges, les donnees experimentales ont ete correlees avec la methode UNIQUAC et des parametres d'interaction binaire ont ete calcules, montrant un ecart avec les donnees de moins de 4%.

This study is a first step towards the prediction of the behaviour of working fluids and compressor oils. Different thermodynamic models are investigated and a modified Flory-Huggins-based predictive model, termed MFH, is proposed for solubility of HFCs in long-chained hydrocarbons. From experimental data, 7 general parameters have been fitted for the MFH model to describe 14 binary systems. The UNIQUAC model demands 28 specific parameters without the possibility of extending their validity to other mixtures. A predictive UNIFAC model requires 8 general parameters, but its uncertainty, 17%. is poor compared to the MFH model's 7%. Cette etude est une premiere etape vers la prediction du comportement de fluides hydrauliques et d'huiles de compresseur. Differents modeles thermodynamiques sont etudies et un modele predictif de Flory-Huggins modifie, appele MFH, est propose pour la solubilite des HFC dans des hydrocarbures a chaine longue. A partir de donnees experimentales, 7 parametres generaux ont ete cales dans le modele MFH afin de decrire 14 systemes binaires. Le modele UNIQUAC exige 28 parametres specifiques sans possibilite d'etendre leur validite a d'autres melanges. Un modele predictif UNIFAC requiert 8 parametres generaux, mais son incertitude, 17%, est mauvaise comparativement aux 7% du modele MFH.

The solubilities of difluoromethane (HFC32), 1,1,1,2,2-pentafluoroethane (HFC125), 1,1,1,2-tetrafluoroethane (HFC134a), 1,1,1-trifluoroethane (HFC143a), and 1,1-difluoroethane (HFC152a) in pentaerythritol tetranonanoate, pentaerythritol tetra-2-ethylbutanoate, and pentaerythritol tetra-2-ethylhexanoate have been measured at temperatures between 303 and 363 K and pressures between 0.07 and 2.1 MPa. Henry's constant and the activity coefficient for HFCs at infinite dilution were derived for measurements below 0.34 MPa. The measurements were made by an isochoric method with an uncertainty of HFC134a > HFC32 > HFC125 > HFC143a. The experimental data have been correlated with a Flory−Huggins model with an extended temperature dependence, which is able to describe the data with a deviation from measured data of