No abstract

The density, viscosity, and thermal conductivity of ethylene glycol + water, diethylene glycol + water, and triethylene glycol + water mixtures were measured at temperatures ranging from 290 K to 450 K and concentrations ranging from 25 mol % glycol to 100 mol % glycol. Our data were generally in agreement with the limited data available in the literature and were correlated using simple empirical expressions and the generalized corresponding states principle (GCSP). The GCSP method, with two adjustable parameters for each property, offers the potential for judicious extrapolation of density and transport property data for all glycol + water mixtures.

A new set of constants for the modified Benedict−Webb−Rubin (MBWR) equation based on the Lennard-Jones (LJ) potential were obtained in the temperature range T* = 0.45 to T* = 6.0 by supplementing computer simulation data with data obtained by recalculating the first five virial coefficients of the LJ potential. These virial coefficients are presented in a detailed table that is suitable for the calculation of the internal energy and pressure of the LJ fluid in the vapor state. The MBWR equation was also extended to the alkanes by including a temperature-dependent energy parameter in the LJ potential. The resulting equation was found to be satisfactory for correlating experimental data for the liquid density and vapor pressure and in predicting the heat capacity of n-alkanes upto n-hexadecane. Only three parameters are required to characterize each n-alkane, and furthermore, the parameters show regular behavior with the number of carbon atoms in the n-alkane.

The speed of sound In liquid methanol has been measured at temperatures from 273 to 333 K and at pressures up to 280 MPa, using a phase comparison pulse-echo technique operating at 2 MHz. The density, the isobarlc thermal expansivity, the Isothermal compressibility, the entropy, the enthalpy, and the specific heat have been evaluated from the measured sound speed following a modified computational method. The derived density data were fitted to a 16-constant equation of state within the accuracy of the measurement. In the region of overlap, the experimental data agree well with those determined by direct measurements.