Correlation 16 (Rackett)

The following table lists the identification numbers of this correlation with respect to some well-known sources of thermodynamic data.

The equation has the following form:

You must use at least 4 coefficients with this correlation.

You can use up to 5 coefficients with this correlation.

You can use the following UOMs:

• The C1 coefficient has units of molar density

• The C3 coefficient has units of absolute temperature (K or R).

• The temperatures should be in Kelvin (K).

The C2 and C3 coefficients cannot equal zero.

This correlation is the same as the IK-CAPE RACK equation when C5 equals zero.

The NIST TDE 10 equation imposes the following restrictions on the coefficients:

• C1 = rC

• C3 = TC

• C4 = 2/7

• C5 = -1

The original Rackett equation1 uses the same restrictions as the NIST TDE 10 equation, but imposes the following additional restriction.

• C2 = ZC

The modified Rackett equation2 uses the following restrictions:

• C1 = PC/(RTC)

• C3 = TC

• C4 = 2/7

• C5 = 0

These restrictions use the following nomenclature.

rC is the critical density

R is the universal gas constant

TC is the critical temperature

PC is the critical pressure

ZC is the critical compressibility factor

Usage

We recommend that you use this correlation to calculate only the following properties:

• Liquid Density

• Liquid Thermal Conductivity

References

1. Rackett, H. G., 1970, Equation of State for Saturated Liquids, J.Chem. Eng. Data 15(4), 514-517.

2. Spencer, C. F. and Danner, R. P., 1972, Improved Equation for Prediction of Saturated Liquid Density, J.Chem. Eng. Data 17(2), 236-241.

3. Thermodynamics-Package for CAPE-Applications. DECHEMA e.V. [Online] March 28, 2002, pp 7-10. http://dechema.de/dechema_media/IK_CAPE_Equations-p-888.pdf (accessed May 1, 2018).