Experimental and PC-SAFT volumetric and phase behavior of carbon dioxide + PAG or POE lubricant systems

Solubilities of CO 2 in synthetic PAG oil from 253 K to 333.15 K were measured. Estimated molecular weight and new experimental densities were used to calculate the characteristic parameters of PC-SAFT for several PAGs. Transferable characteristic parameters were used for POEs. Phase and volumetric behavior of CO 2-PAG and CO 2-POE systems were modelled using a k ij interaction parameter linear with the temperature. ▪ In this work we have measured densities of a synthetic PAG oil from 283.15 K to 333.15 K and solubilities of CO 2 in this oil from 253 K to 333.15 K. Molecular weight of the lubricant was estimated using fast atom bombardment (FAB). Molecular weight and experimental densities were used to calculate characteristic parameters of PC-SAFT model for several commercial PAG oils. Transferable characteristic parameters were used for POEs. Saturated and compressed densities together with the phase behavior (solubility, vapour–liquid equilibria, liquid–liquid equilibria, vapour–liquid–liquid equilibria and miscibility) of CO 2-PAG and CO 2-POE systems were modelled with PC-SAFT using a k ij interaction parameter linear with the temperature. Experimental data have been successfully represented with the present model, which was used to predict the phase diagram type in the mixtures of CO 2 with PAG or POE lubricant oils.