Soave-Redlich-Kwong Equation Formula
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| \( p \;=\; \dfrac{ R \cdot T_a }{ V - b } - \dfrac{ a \cdot \alpha (T) }{ V \cdot (V + b ) } \) | ||
| Symbol | English | Metric |
| \( p \) = Fluid Pressure | - | \(m^3\;/\;mol\) |
| \( R \) = Universal Gas Constant | - | \(J\;/\;kmol-K\) |
| \( T_a \) = Absolute Temperature | - | \(^\circ K\) |
| \( V \) = Fluid Molar Volume | - | \(m^3 \;/\;mol\) |
| \( b \) = Volume (Molecular Size) | - | \(m^3 \;/\;mol\) |
| \( a \) = Attractive Force | - | \(Pa \cdot m^6 \cdot K^{0.5} \;/\;mol^2\) |
| \( \alpha (T) \) (Greek Symbol alpha) = Temperature Dependent Attraction | - | \(dimensionless\) |
Soave–Redlich–Kwong equation of state, abbreviated as \(SRK\), is a cubic thermodynamic model used to describe the pressure–volume–temperature (PVT) behavior of real gases and liquids, especially in vapor–liquid equilibrium calculations. It is a modification of the original Redlich–Kwong equation to improve accuracy near the saturation region. The key enhancement is the inclusion of a temperature-dependent attraction term that incorporates the acentric factor, allowing the equation to better represent the effects of molecular shape and polarity. Because of this improvement, the SRK equation provides more reliable predictions of phase behavior, compressibility, and equilibrium properties for many nonpolar and mildly polar substances. It is widely used in chemical and petroleum engineering for modeling hydrocarbons, natural gas systems, and separation processes such as distillation and condensation.
Soave-Redlich-Kwong Equation Formulas |
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\( b \;=\; 0.08664 \cdot \dfrac{ R \cdot T_c }{ P_c } \) \( a \;=\; 0.42747 \cdot \dfrac{ R^2 \cdot T_c^2 }{ P_c } \) \( \alpha (T) \;=\; [ \; 1 + m \cdot ( \;1 - \sqrt{ T_r } \; ) \; ]^2 \) \( m \;=\; 0.480 + 1.574 \cdot \omega - 0.176 \cdot \omega^2 \) \( T_r \;=\; \frac{ T }{ T_c } \) |
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| Symbol | English | Metric |
| \( b \) = Volume (Molecular Size) | - | \(m^3\;/\;mol\) |
| \( a \) = Attractive Force | - | \(Pa \cdot m^6 \cdot K^{0.5} \;/\;mol^2\) |
| \( R \) = Universal Gas Constant | - | \(J\;/\;kmol-K\) |
| \( T_c \) = Critical Temperature | - | \(^\circ K\) |
| \( P_c \) = Critical Pressure | - | \(Pa\) |
| \( \alpha (T) \) (Greek Symbol alpha) = Temperature Dependent Attraction | - | \(dimensionless\) |
| \( m \) = A Function of the Acentric Factor | - | \(dimensionless\) |
| \( T \) = System Temperature | - | \(^\circ K\) |
| \( T_r \) = Reduced Temperature | - | \(^\circ K\) |
| \( \omega \) (Greek Symbol omega) = Acentric Factor | - | \(dimensionless\) |