Based on the Mie potential function theory and London dispersion forces theory

and with the introduction of Leland’s molecular shape factors to modify the inadequacy of the two parameters corresponding states principle for complex fluids

a new correlation for binary interaction parameters of the equation of state was proposed.The pseudocritical rules of Joffee and Stewart were introduced to evaluate the molecular shape factors of mixtures in the deduction process.When Mie potential constant was set to be 3

the new correlation obtained could be used to evaluate the binary interaction parameters of paraffins mixture without back-calculation.The new correlation showed that besides the critical properties of components in paraffins mixture

the binary interaction parameters were the function of composition

temperature

molar volume

acentric factor and component’s ionization potential.Satisfying results with the maximum average absolute error of 2.40%

were achieved when the correlation was used in the Peng-Robinson equation of state to calculate the critical pressure of paraffins mixture.