In this project it is proposed to study the enthalpy and phase behavior of a model system, methanol (which is hydrogen bonding) /n-pentane (non-polar)/acetone (polar), that is representative of interactions present in mixtures containing a non-polar, a polar and a hydrogen bonding compound. Studies will be conducted at elevated temperatures (375 to 700 degrees K) and pressures (0.1 to 10MPa) including the critical and supercritical regions. Primary measurements will be made in a Freon 11 reference fluid boil-off calorimeter, and an equilibrium flash vaporization apparatus, which have already been developed. Additional measurements will be made in the critical region using a new automated flow calorimeter. This system is studied in part because some phase behavior data are available for this system at lower temperatures. Enthalpy and phase behavior measurements will also be made for the three pure compounds, the three binary mixtures, and selected compositions of the ternary. This set of data will be used as a standard for correlation of equations of state applicable for both phase behavior and enthalpy predictions of such highly non-ideal mixtures. Experimental results at subcritical conditions have recently been obtained for a different ternary system--tetralin/quinoline/m- cresol. Comparison of these results with correlations has shown that present equation of state methods cannot be used to predict both phase behavior and enthalpy of binary and ternary systems, containing polar associating compounds. Therefore, equation of state development will continue, emphasizing perturbed hard body equations, with the objective of developing equation of state methods that are applicable to non-ideal ternary mixtures that can serve as models of the complex systems often encountered in industrial practice.
