Viscosity of methyl and ethyl esters: Experiments and modeling

Abstract

Viscosity and density have been measured for a number of ethyl esters (ethyl ethanoate, ethyl butanoate, ethyl dodecanoate and ethyl tetradecanoate) at four temperatures between 288.15 and 323.15 K at 101.3 kPa. The measurements are also reported for four of their binary mixtures, over the whole range of compositions, as well as for a single, equimolar ternary and one equimolar, quaternary mixture. The viscosity was measured with a Stabinger viscometer, whilst the density was measured by means of a vibrating U-tube densimeter. The combined expanded uncertainty (k ≈ 2) for the density is 1.7 kg⋅m−3, and relative one for the viscosity is 0.014. The measured viscosity of pure ethyl esters, together with the published literature values, were correlated by means of the extended hard-sphere (EHS) model that has its basis in kinetic theory and the molecular description of the fluid. A separate correlation was developed for methyl esters, based only on the published viscosity values. The correlations, for both families of esters, are valid in the temperature range 283 to 373 K and pressures up to 200 MPa, for all the esters up to and including methyl tetracosanotae and ethyl eicosanoate. The EHS model was used to predict the viscosity of mixture of esters. The measured viscosity data were represented with the average absolute deviation of 2.5% and a maximum deviation of 6.4%.