The equipment for surface tension measurement by the improved differential maximum bubble pressure method was built and tested.The surface tension of a binary mixture of p-xylene and acetic acid was measured over the ...The equipment for surface tension measurement by the improved differential maximum bubble pressure method was built and tested.The surface tension of a binary mixture of p-xylene and acetic acid was measured over the entire concentration range from 303.15 K to 343.15 K under atmospheric pressure.The experimental values were correlated with two methods.It is useful for PTA plant design.展开更多
Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state, the factor a in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by origi...Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state, the factor a in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by original and modified SRK equation of state combined with MHV1 mixing rule and UNIFAC model, respectively. For 1447 saturated pressure points of 37 substance including alkanes; organics containing chlorine, fluorine, and oxygen; inorganic gases and water, the original SRK equation of state predicted pressure with an average deviation of 2.521% and modified one 1.673%. Binary vapor-liquid equilibria of alcohols containing mixtures and water containing mixtures also indicated that the SRK equation of state with the modified a had a better precision than that with the original one.展开更多
Alpha functions of Soave-Redlich-Kwong （SRK） equation of state proposed by Soave, Twu, and Luo were different in mathematic tendency. They were compared in modeling methane-alkanes equilibria with van der Waals mixi...Alpha functions of Soave-Redlich-Kwong （SRK） equation of state proposed by Soave, Twu, and Luo were different in mathematic tendency. They were compared in modeling methane-alkanes equilibria with van der Waals mixing rule and Modified Huron-Vidal （MHV1） mixing rule, respectively. Results showed that Luo＇s alpha function was a little more accurate than Soave＇s, and Twu＇s alpha function lacked accuracy in modeling methane-alkanes equilibrium. SRK equation of state was expanded as virial form, and then the equivalent terms were contrasted with terms of virial equation of state. Results showed that Soave＇s and Luo＇s alpha functions matched the tendency of virial coefficient better than Twu＇s, and Luo＇s alpha function matched better than Soave＇s in wide temperature range, which sustained the conclusions of phase equilibria calculation. Luo＇s alpha function keeps decreasing when Tr〉 1 and becomes negative at sufficient high temperature, thus the conventional cubic equation of state expressed pressure as the sum of repulsion pressure PR （〉0）, and attraction pressure PA （〈0） could be improved to be the sum of hard-sphere repulsion pressure PH （〉0） and intermolecular force pressure P1 （P1〈0 at low temperature and p1〉0 at sufficient high temperature）.展开更多
文摘The equipment for surface tension measurement by the improved differential maximum bubble pressure method was built and tested.The surface tension of a binary mixture of p-xylene and acetic acid was measured over the entire concentration range from 303.15 K to 343.15 K under atmospheric pressure.The experimental values were correlated with two methods.It is useful for PTA plant design.
文摘Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state, the factor a in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by original and modified SRK equation of state combined with MHV1 mixing rule and UNIFAC model, respectively. For 1447 saturated pressure points of 37 substance including alkanes; organics containing chlorine, fluorine, and oxygen; inorganic gases and water, the original SRK equation of state predicted pressure with an average deviation of 2.521% and modified one 1.673%. Binary vapor-liquid equilibria of alcohols containing mixtures and water containing mixtures also indicated that the SRK equation of state with the modified a had a better precision than that with the original one.
文摘Alpha functions of Soave-Redlich-Kwong （SRK） equation of state proposed by Soave, Twu, and Luo were different in mathematic tendency. They were compared in modeling methane-alkanes equilibria with van der Waals mixing rule and Modified Huron-Vidal （MHV1） mixing rule, respectively. Results showed that Luo＇s alpha function was a little more accurate than Soave＇s, and Twu＇s alpha function lacked accuracy in modeling methane-alkanes equilibrium. SRK equation of state was expanded as virial form, and then the equivalent terms were contrasted with terms of virial equation of state. Results showed that Soave＇s and Luo＇s alpha functions matched the tendency of virial coefficient better than Twu＇s, and Luo＇s alpha function matched better than Soave＇s in wide temperature range, which sustained the conclusions of phase equilibria calculation. Luo＇s alpha function keeps decreasing when Tr〉 1 and becomes negative at sufficient high temperature, thus the conventional cubic equation of state expressed pressure as the sum of repulsion pressure PR （〉0）, and attraction pressure PA （〈0） could be improved to be the sum of hard-sphere repulsion pressure PH （〉0） and intermolecular force pressure P1 （P1〈0 at low temperature and p1〉0 at sufficient high temperature）.
