TY - JOUR
T1 - Matching the critical point of associating fluids with the Cubic Plus Association equation of state
AU - Liang, Xiaodong
AU - Peng, Baoliang
AU - Chen, Yuan
AU - Luo, Jianhui
AU - Michelsen, Michael Locht
AU - Kontogeorgis, Georgios M.
PY - 2020
Y1 - 2020
N2 - Simultaneous description of critical point, vapor pressure and liquid density with an equation of state has been a hot research topic. In this work, the possibilities and limitations of the Cubic Plus Association equation of state for describing these properties of associating fluids have been studied. First a procedure is developed to determine the energy and co-volume parameters by converting the system of three equations at the critical point to a single variable root-finding problem. The procedure is then used in parameter estimation to simultaneously match the critical temperature and pressure as well as fit the vapor pressure and liquid molar volume of typical associating fluids. The performance of the estimated parameters is subsequently compared with the parameters fitted only to vapor pressure and liquid molar volume. The possibility of introducing an extra adjustable parameter to improve the performance is further explored. The results show that, for the studied associating fluids, the Cubic Plus Association equation of state with the obtained parameters can match the critical temperature and pressure exactly, fit the vapor pressure within 2% and the liquid molar volume within 3–4% in the range of temperature up to 0.95 critical temperature, while the model overpredicts the critical volume up to 18%.
AB - Simultaneous description of critical point, vapor pressure and liquid density with an equation of state has been a hot research topic. In this work, the possibilities and limitations of the Cubic Plus Association equation of state for describing these properties of associating fluids have been studied. First a procedure is developed to determine the energy and co-volume parameters by converting the system of three equations at the critical point to a single variable root-finding problem. The procedure is then used in parameter estimation to simultaneously match the critical temperature and pressure as well as fit the vapor pressure and liquid molar volume of typical associating fluids. The performance of the estimated parameters is subsequently compared with the parameters fitted only to vapor pressure and liquid molar volume. The possibility of introducing an extra adjustable parameter to improve the performance is further explored. The results show that, for the studied associating fluids, the Cubic Plus Association equation of state with the obtained parameters can match the critical temperature and pressure exactly, fit the vapor pressure within 2% and the liquid molar volume within 3–4% in the range of temperature up to 0.95 critical temperature, while the model overpredicts the critical volume up to 18%.
KW - CPA EOS
KW - Critical point
KW - Parameter estimation
KW - Associating fluids
U2 - 10.1016/j.fluid.2020.112674
DO - 10.1016/j.fluid.2020.112674
M3 - Journal article
SN - 0378-3812
VL - 526
JO - Fluid Phase Equilibria
JF - Fluid Phase Equilibria
M1 - 112674
ER -