# Redlich-Kwong Equation of State

on . Posted in Thermodynamics

Redlich-Kwong equation of state is another thermodynamic model used to describe the behavior of fluids, especially gases and liquids.  Like the Peng-Robinson equation, the Redlich-Kwong equation aims to provide a more accurate representation of real fluid behavior compared to the simpler Van der Waals equation.

Similar to the Peng-Robinson equation, the parameter "a" accounts for the molecular attractions between particles, while the parameter "b" accounts for the volume occupied by the molecules themselves.  These parameters are determined based on the critical properties (critical temperature and critical pressure) and other experimental data of the fluid.

The Redlich-Kwong equation of state, like the Peng-Robinson equation, can be used to calculate various thermodynamic properties of the fluid, including pressure, volume, temperature, and compressibility factor.  It is also widely employed in the design and analysis of chemical processes, petroleum engineering, and other fields where accurate modeling of fluid behavior is crucial.

Both the Peng-Robinson and Redlich-Kwong equations of state are important tools in chemical engineering and thermodynamics for modeling the behavior of real gases and liquids under various conditions.  Each equation has its strengths and weaknesses, and the choice between them often depends on the specific application and the accuracy required for the system being studied.

### Redlich-Kwong Equation of State

$$p = (R \; T \;/\; V - b ) - [ a \;/\; T^{0.5} V \; (V + b )\; ]$$
Symbol English Metric
$$p$$ = pressure of fluid $$lbf \;/\; in^2$$ $$Pa$$
$$R$$ = universal gas constant $$lbf-ft\;/\;lbmol-R$$ $$J\;/\;kmol-K$$
$$T$$ = temperature $$F$$ $$K$$
$$V$$ = molar volume of fluid $$in^3$$ $$mm^3$$
$$b$$ = parameters specific to the fluid, known as the Redlich-Kwong parameters $$in^3$$  $$mm^3$$
$$a$$ = parameters specific to the fluid, known as the Redlich-Kwong parameters - -

Tags: Gas Ideal Gas