Twu-Sim-Tassone equation of state: Difference between revisions

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:<math>p=\frac{RT}{V_m-b}-\frac{a}{(V_m-0.5b)(V_m+3b)}</math>
:<math>p=\frac{RT}{V_m-b}-\frac{a}{(V_m-0.5b)(V_m+3b)}</math>


Where <math>V_m</math> is the molar volume, and <math>a</math> and <math>b</math> are the attractive and repulsive parameters akin to those of the [[Van der Waals equation of state]].  Relations exists between <math>a</math> and <math>b</math> and the critical parameters <math>T_c</math> and <math>P_c</math> in the forms (Eqs. 3 and 4):
Where <math>V_m</math> is the molar volume, and <math>a</math> and <math>b</math> are the attractive and repulsive parameters akin to those of the [[Van der Waals equation of state]].  Relations exists between <math>a</math> and <math>b</math> and the critical parameters <math>T_c</math> and <math>p_c</math> in the forms (Eqs. 3 and 4):


:<math>a_c=0.470507  \frac{ R^2T_c^2}{P_c}</math>
:<math>a_c=0.470507  \frac{ R^2T_c^2}{p_c}</math>
:<math>b_c=0.0740740  \frac{ RT_c}{P_c}</math>
 
:<math>b_c=0.0740740  \frac{ RT_c}{p_c}</math>


==References==
==References==

Revision as of 15:27, 7 November 2011

Twu, Sim and Tassone presented a cubic equation of state for accurate representation of hydrocarbons that has become known as the Twu-Sim-Tassone or TST equation of state[1]. With a critical compressibility factor of (Eq. 5)

Zc=pcvcRTc=0.296296

it better represents the compressibility than many of than the Redlich-Kwong equation of states, including the Soave modified version, and the Peng and Robinson equation of state.

The equation follows the general cubic form resulting in the equation (Eq. 2):

p=RTVm−b−a(Vm−0.5b)(Vm+3b)

Where Vm is the molar volume, and a and b are the attractive and repulsive parameters akin to those of the Van der Waals equation of state. Relations exists between a and b and the critical parameters Tc and pc in the forms (Eqs. 3 and 4):

ac=0.470507R2Tc2pc
bc=0.0740740RTcpc

References

Related reading