Available mixing rules for liquid conductivity

You can use one of the following mixing rules to calculate the bulk liquid thermal conductivity of a Fluid Type.

SimSci Mixing Rule

where

lm is the liquid thermal conductivity of the mixture

li is the liquid thermal conductivity of pure component i

wi is the weight composition fraction of component i in the liquid phase

This is the default mixing rule. It is the same as the DIPPR 9H mixing rule.

Molar Average

where

xi is the molar composition fraction of component i in the liquid phase

Logarithmic Molar Average

DIPPR Mixing Rule

where

fi is the volume fraction of pure component i

Vi is the liquid molar volume of pure component i

This mixing rule is the same as the DIPPR 9I mixing rule and the DIKL equation from the IK-CAPE thermodynamics package.

Li Mixing Rule

where

Fi is the superficial volume fraction of component i

TRAPP (transport property prediction)[3,4]

We evaluate the liquid thermal conductivity based on the deviations in a reference fluid, which we assume to be the pure liquid of a reference component, R. We use the following equations to calculate the liquid thermal conductivity of the mixture (lm):

where

lm0 is the liquid thermal conductivity of the mixture at low pressure and temperature, which we calculate by using the liquid thermal conductivities from the Lee-Kesler equation of state (EOS) and the SimSci mixing rule

Ci are a set of constant coefficients taken from literature[5]

rc,R is the density of reference component R at its critical temperature and pressure

rc,i is the density of component i at its critical temperature and pressure

MR is the molar mass of reference component R

Pisat is the vapor pressure of component i at the system temperature (T)

PRsat(T0) is the vapor pressure of reference component R at temperature T0

risat is the saturated liquid density of component i at the system temperature (T)

rRsat(T0) is the saturated liquid density of reference component R at T0

wi is the acentric factor of component i

wR is the acentric factor of reference component R

Zc,i is the critical compressibility factor of component i

Zc,R is the critical compressibility factor of reference component R

Because we evaluate the vapor pressure and saturated liquid density of the reference fluid at T0, we must iteratively solve for fi.

Typically, you use this mixing rule for systems of non-polar components when Tr > 0.7.

Power Molar Average (Vredeveld)

where

r is an exponent that you specify in the Fluid Editor

References

1. Li, C. C. Thermal Conductivity of Liquid Mixtures. AIChE J. 1976, 22 (5), 927–930.

2. Poling, B. E.; Prausnitz, J. M.; O'Connell, J. P. The Properties of Gases and Liquids, 5th ed.; McGraw-Hill: New York, 2001; p. 624.

3. Leland, T. W.; Robinson, J. S.; Suther, G.A. Statistical Thermodynamics of Mixtures of Molecules of Different Sizes. Trans. Farad. Soc. 1968, 64, 1447-1460.

4. Ely, J. F.; Hanley, H. J. M. Prediction of Viscosity and Thermal Conductivity in Hydrocarbon Mixtures- Computer Program TRAPP. Proceedings of the 60th Annual Convention of the Gas Processors Association, San Antonio, TX, USA, Mar 23, 1981.

5. Reid, R. C.; Prausnitz, J. M.; Poling, B. E. The Properties of Gases and Liquids, 5th ed.; McGraw-Hill: New York, 1977; pp. 572-577.