Generalized correlations for calculating the density of ionic liquids at 0.1 MPa and higher pressures

A simple and accurate generalized correlation for calculating the liquid densities of ionic liquids (ILs) at 0.1 MPa is proposed by modifying a previously developed liquid density correlation for refrigerants. With no adjustable parameter and for a wide range of temperature commonly used in IL applications, the percent average absolute deviation (%AAD) in calculating 1036 liquid density data points for 52 ILs was found to be 1.54%. To perform calculations, the developed model employs the critical temperature, the critical density and the acentric factor of ILs. When compared with 9 other generalized correlations, the new correlation was found to be superior. The %AAD for the next best correlation for the same temperature range and number of data points was found to be 2.35%. At pressures well above 0.1 MPa and for a wide temperature range, the developed correlation of this work was coupled with seven relationships for predicting the liquid densities of ILs at high pressures. The best relationships were found to be the ones developed by Tait, Chang and Zhao (CZ) and Nasrifar and co-workers (NAM) in predicting the liquid densities of 41 ILs comprising 6093 data points. The %AAD was found to be 2.08%, 2.10% and 2.13%, respectively, for coupling of the new generalized correlation with the relationships provided by Tait, CZ and NAM.