THE INFLUENCE OF TERNARY INTERACTION PARAMETERS ON THE REPRESENTATION OF THE HIGH-PRESSURE FLUID PHASE EQUILIBRIA OF TERNARY SYSTEMS

PISONI, G. O.; CISMONDI DUARTE, MARTIN; ZABALOY, M.

Natal

Congreso; II Iberoamerican Conference on Supercritical Fluids ?PROSCIBA 2010?; 2010

Models of the equation of state (EOS) type, used for describingfluid phase equilibria, typically assume that the system behavior can bedescribed from binary contributions only. This is not enough for obtaininggood predictions for the high-pressure phase equilibria of ternary highly nonideal systems. On the other hand, cubic mixing rules (CMRs) provide both,binary and ternary interaction parameters. By fitting such ternary parameters,it is possible to improve the reproduction of ternary experimental data whileleaving invariant the description of the three constituent binary subsystems. Inthis work, we test the CMRs approach by studying the system Carbon Dioxide+ n-Hexadecane + 1,8-Octanediol, for which we have available both, binaryand ternary phase equilibrium data. For such system, we show the influence ofthe ternary parameters on the size of ternary two-phase and three-phaseimmiscibility regions. We also consider the effect of predicted values of theternary parameters, which we need when ternary experimental data are notavailable. We use in this study the the Peng-Robinson (PR) EOS and reachconclusions on how the PR-EOS compares to the RK-PR EOS, when bothEOSs are coupled to CMRs.