Mmkmk

a vailable method. Previously the authors have shown that
for predicting the saturated liquid density of pure compounds the Rackett equation is accurate, simple, and
versatile ( 3 7 ) . The extension of t his correlation to
m ixtures should prove useful in numerous applications.
F or t he systems of Tables I l l a nd I V H armen's method
for predicting bubble-point densities is essentiallyequivalent in accuracy t o E quation 1 0. I n order t o m aintain this
accuracy, however, both Harmen's method and the proposed method require one empirical constant ( C for the
method of H armens and Z R A for E quation IO). One contrast in the iwo methods is the range of compounds f or
w hich they can be applied. Whereas Harmens' method
was developed mainly for hydrocarbons in the C1-C7
range, the modified Rackett equation has been shown to
b e reliable for heavier hydrocarbons, organic compounds,
and inorganic compounds ( 37).

N omenclature

K = c orrelating parameter of Lu chart
N = n umber of d ata points
P c = c ritical pressure, atm
P r = r educed pressure, P / P c
R = u niversal gas constant, 82.06 atm c m 3 / g mol K
T = t emperature, K
T c = c riticaltemperature, K
T c m = p seudocritical temperature of m ixture, K
T r = r educed temperature, T / T c m
V b p = b ubble-point volume, c m 3 / g mol
V c m = p seudocritical volume of mixture, c m 3 / g mol
V s = v olume of saturated liquid, c m 3 / g mol
Z c = c ritical compressibility factor
Z c m = c ritical compressibility factor f or m ixture
Z R A = c onstant of modified Rackett equation
G reekL etters
p bp = b ubble-point density, g m o l / c m 3
p c = c ritical density, g mol/cm3

P r = r educed density, p / p c
P S = s aturated liquid density, g m o l / c m 3
Literature Cited
A merican Petroleum Institute, "Technical Data Book, Petroleum Refining," 2nd ed. American Petroleum Institute, Washington, D.C..
1 971.
Chueh, P. L . , P rausnitz, J. M.. AlChEJ.. 13, 1099 (1967).Guggenheim, E. A., "Thermodynamics." 2nd ed., p. 168, Interscience. New York, N.Y.. 1949.
Gunn, R . D ., Chueh. P. L., Prausnitz. J. M., AIChE J . , 1 2, 937
(1966).
Harmens, A.. Chem. Eng. S ci.. 2 0,813-22 (1965)
Harmens, A., i bid., 21, 725 (1966).
Kay. W. B., Ind. Eng. Chem., 30,459 (1938).
Kay, W . B .,bid.. 32,353 (1940).
i
Kay, W. B ., i bid.. 33, 590 (1941).
Kay, W. €3.. i bid.. 40, 1459 (1948)
Kay, W. B., J . Chem. Eng. Data. 1 5 , 4 6 ( 1970).
Kay. W. 6.. Albert. R . E . , I nd. E ng. C hem. 4 8, 422 (1956).
Kay, W. B . , Bierlein. J. A,, i bid., 4 5, 618 (1953).
Kay, W. B., Brice, D . B ., i bid., 4 5, 615 (1953).
Kay, W. 8..N evens, T. D., Chem. Eng. Progr. Symp. Ser. N o. 3,
4 8, 108 (1952).
Kay. W. B ., R ambosek. G. M., I nd. Eng. Chem.. 4 5, 221 (1953).
Li.C. C., Can. J . Chem. E ng., 1 9, 709 (1971).
Lu. B. C.-Y., Chem. Eng., 6 6 ( 9 ) . 137 (1959).
Nichols, W. B., Reamer, H . H .. Sage. 8 . H .. A lChE J . . 3, 262
119571 .
I
,

Phillips, E . M . , Thodos. G., ibid.. 7 , 413 (1961).
Rackett. H. G..J. Chem. Eng. Data, 1 6, 308 (1971).

Rea. H . R .. SDencer. C . F ., D anner, R . P .. ibid., 1 8 ( 2 ) , 227 (1973)
Reamer. H. H . , Sage,8 . H .. ibid.. 7 , 161 (1962).
Reamer, H . H .. Sage, B. H.. ibid., 8 , 508 (1963).
Reamer, H . H .. Sage, E. H .. i bid.. 11, 1 7 (1966).
Reamer, H. H., Sage, B. H ., Lacey. W. N.. ; bid., 1, 29 (1956).
Ritter. R . B .. L enoir, J . M .. Schweppe. J. L., Petrol. Refiner, 37
( 111, 225 (1958).
Sage, B. H.. Lacey. W. N . . Monograph for API Research Project
N o. 3 7, "Some Properties of theLighter Hydrocarbons, Hydrogen
Sulfide and Carbon Dioxide." American Petroleum Institute, Washington, D.C., 1955.
( 29) Sage, B. H ., Lacey, W. N .. Monograph for APi Research Project
N o. 3 7, "Thermodynamic Properties of the Lighter Paraffin Hydrocarbons and Nitrogen," American Petroleum Institute, Washington,
D.C.. 1950.
( 30) Sage, B. H., Reamer, H. H., J . Chem. E ng. D ata, 9 , 26...