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Aspen Physical Property System - Physical Property Models

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kb,ij<br />

=<br />

ka,ij = ka,ji<br />

lij = -lji<br />

kb,ij = kb,ji<br />

The binary parameters ka,ij, kb,ij, and lij are temperature-dependent. In most<br />

cases, ka,ij 0 and lij 0 are sufficient to represent the system of interest.<br />

VLE calculations are independent of c. However, c does influence the fugacity<br />

values and can be adjusted to (liquid) molar volumes. For a wide temperature<br />

range, adjust ci0 to the molar volume at 298.15K or at boiling temperature.<br />

The ai are calculated using the Extended Mathias Alpha Function, as described<br />

in Soave Alpha Functions.<br />

Warning: Using c1i and c2i can cause anomalous behavior in enthalpy and<br />

heat capacity. Their use is strongly discouraged.<br />

Parameter<br />

Name/Element<br />

58 2 Thermodynamic <strong>Property</strong> <strong>Models</strong><br />

Symbol Default MDS Lower<br />

Limit<br />

Upper<br />

Limit<br />

Units<br />

TCRKU T ci TC x 5.0 2000.0 TEMPERATURE<br />

PCRKU p ci PC x 105 108 PRESSURE<br />

OMGRKU � i<br />

OMEGA x -0.5 2.0 —<br />

RKUPP0 †† q 0i — x — — —<br />

RKUPP1 †† q 1i 0 x — — —<br />

RKUPP2 †† q 2i 0 x — — —<br />

RKUC0 c 0i 0 x — — ‡<br />

RKUC1 c 1i 0 x — — ‡<br />

RKUC2 c 2i 0 x — — ‡<br />

RKUKA0 ††† k a,ij 0<br />

RKUKA1 ††† k a,ij 1<br />

RKUKA2 ††† k a,ij 2<br />

RKULA0 ††† l ij 0<br />

RKULA1 ††† l ij 1<br />

RKULA2 ††† l ij 2<br />

RKUKB0 ††† k b,ij 0<br />

RKUKB1 ††† k b,ij 1<br />

RKUKB2 ††† k b,ij 2<br />

0 x — — —<br />

0 x — — TEMPERATURE<br />

0 x — — TEMPERATURE †<br />

0 x — — —<br />

0 x — — TEMPERATURE<br />

0 x — — TEMPERATURE †<br />

0 x — — —<br />

0 x — — TEMPERATURE<br />

0 x — — TEMPERATURE †<br />

† Absolute temperature units are assumed for ka,ij 2 , lij 2 , and kb,ij 2 .<br />

†† For polar components (dipole moment >> 0), if you do not enter q0i, the<br />

system estimates q0i, q1i, q2i from vapor pressures using the Antoine vapor<br />

pressure model.<br />

††† If you do not enter at least one of the binary parameters ka,ij 0 , ka,ij 2 , lij 0 ,<br />

lij 2 , kb,ij 0 , or kb,ij 2 the system estimates ka,ij 0 , ka,ij 2 , lij 0 , and lij 2 from the UNIFAC<br />

or Hayden O'Connell models.

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