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The virial expansion is a model of thermodynamic equations of state.It expresses the pressure P of a gas in local equilibrium as a power series of the density.This equation may be represented in terms of the compressibility factor, Z, as = + + + This equation was first proposed by Kamerlingh Onnes. [1]
The Benedict–Webb–Rubin–Starling [13] equation of state is a modified BWR equation of state and can be written as = + (+) + (+) + (+) Note that in this virial equation, the fourth and fifth virial terms are zero.
The virial theorem states that if dG/dt τ = 0, then = = . There are many reasons why the average of the time derivative might vanish. One often-cited reason applies to stably bound systems, that is, to systems that hang together forever and whose parameters are finite.
1.6 Virial model. 1.7 Peng–Robinson model. ... the equation of state can be written in the reduced form: = ′ ′ (+ ′) with ′ = Berthelot and modified ...
A starting point for the development can be taken as the virial equation of state for a gas. = + + + … where is the pressure, is the volume, is the temperature and ,,... are known as virial coefficients.
In physics and thermodynamics, the Redlich–Kwong equation of state is an empirical, algebraic equation that relates temperature, pressure, and volume of gases. It is generally more accurate than the van der Waals equation and the ideal gas equation at temperatures above the critical temperature .
The cubic-plus-chain (CPC) [28] [29] [30] equation of state hybridizes the classical cubic equation of state with the SAFT chain term. [21] [22] The addition of the chain term allows the model to be capable of capturing the physics of both short-chain and long-chain non-associating components ranging from alkanes to polymers. The CPC monomer ...
Compressibility factor values are usually obtained by calculation from equations of state (EOS), such as the virial equation which take compound-specific empirical constants as input. For a gas that is a mixture of two or more pure gases (air or natural gas, for example), the gas composition must be known before compressibility can be calculated.