Comparison of modified alpha functions of the PR-EoS for volume and enthalpy prediction of natural gases.

Comparison of modified alpha functions of the PR-EoS for volume and enthalpy prediction of natural gases. An Acad Bras Cienc. 2020;92(3):e20190603 Authors: GonÇalves AF, Costa AOSD, Costa Junior EFD Abstract Proper simulation of processes of the natural gas industry such as dehydration, liquefaction and regasification require accurate prediction of thermodynamic properties of the working fluids. For such processes, cubic equations of state are the calculation methods most frequently employed. Among them, the Peng-Robinson equation is usually the one recommended for gas, refinery and petrochemical applications in many simulators. Numerous works have been proposed in order to improve the temperature dependence relation of the attraction parameter of the equation - the so called alpha function. In this work, five currently available alpha functions are evaluated for the prediction of molar volumes and enthalpies of natural gas samples. Additionally, parameters of one of the models are readjusted to volumetric data of methane, in order to represent its supercritical behavior more accurately. Experimental data of 44 mixtures are compared with calculated results. Van der Waals mixing rules are used, with binary interaction parameters set as zero. In the case of the original alpha function, it is also tested how the inclusion of non-zero binary parameters affects the predictions. The extended Saffari-Zahedi model presents the smallest aver...
Source: An Acad Bras Cienc - Category: Science Authors: Tags: An Acad Bras Cienc Source Type: research