Measurement and correlation of the (p, ρ, T) behavior of liquid propylene glycol at temperatures from (272.7 to 393.0) K and pressures up to 91.4 MPa

Abstract

The (p, ρ, T) behavior of propylene glycol was investigated in the homogeneous liquid phase over the temperature range from (272.7 to 393.0) K at pressures from (5.0 to 91.4) MPa. A commercially-available high-pressure vibrating-tube densimeter was utilized to perform the measurements. The measuring system was calibrated by using water and helium as reference fluids, and the calibrated system was validated by measurements of argon and propane. Prior to the measurements, the propylene glycol sample with a purity of 98.8 mol-% was degassed by several freeze-pump-thaw cycles. Considering the measurement uncertainties in temperature, pressure and oscillation period, and uncertainties resulting from instrument calibration and sample impurities, the combined expanded uncertainty (k = 2) in density was estimated to be 1.78 kg·m−3. Using the new experimental data, a correlation equation for the (p, ρ, T) behavior of propylene glycol was established; in the investigated (p, T) range, the combined expanded uncertainty (k = 2) is also 1.78 kg·m−3. The agreement of the carefully selected experimental data from literature and the correlation equation is within the uncertainty of the equation.