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

In this work we have measured densities of a synthetic PAG oil from 283.15 K to 333.15 K and solubilities of CO2 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 CO2-PAG and CO2-POE systems were modelled with PC-SAFT using a kij 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 CO2 with PAG or POE lubricant oils.