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Aspen Physical Property System - Physical Property Models

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Parameter Symbol Default MDS Lower<br />

Name/Element<br />

Limit<br />

3 Transport <strong>Property</strong> <strong>Models</strong> 251<br />

Upper<br />

Limit<br />

Units<br />

MULNVE/2, 3, 4 C 2i, C 3i, C 4i 0 X — — TEMPERATURE<br />

MULNVE/5 C 5i 0 X — — TEMPERATURE<br />

MULNVE/6 C 6i 1000 X — — TEMPERATURE<br />

References<br />

R.C. Reid, J.M. Prausnitz, and B.E. Poling, The Properties of Gases and<br />

Liquids, 4th ed., (New York: McGraw-Hill, 1987), p. 439.<br />

API Liquid Viscosity<br />

The liquid mixture viscosity is calculated using a combination of the API and<br />

General equations. This model is recommended for petroleum and<br />

petrochemical applications. It is used in the CHAO-SEA, GRAYSON, LK-PLOCK,<br />

PENG-ROB, and RK-SOAVE option sets.<br />

For pseudocomponents, the API model is used:<br />

Where:<br />

fcn = A correlation based on API Procedures and Figures 11A4.1, 11A4.2,<br />

and 11A4.3 (API Technical Data Book, Petroleum Refining, 4th<br />

edition)<br />

Vm l is obtained from the API liquid volume model.<br />

For real components, the General model is used.<br />

Parameter<br />

Name/Element<br />

Symbol Default MDS Lower<br />

Limit<br />

Upper<br />

Limit<br />

Units<br />

TB T bi — — 4.0 2000.0 TEMPERATURE<br />

API API i — — -60.0 500.0 —<br />

API 1997 Liquid Viscosity<br />

The liquid mixture viscosity is calculated using a combination of the API and<br />

General equations. This model is recommended over the earlier API viscosity<br />

model.<br />

This model is applicable to petroleum fractions with normal boiling points from<br />

150 F to 1200 F and API gravities between 0 and 75. Testing by <strong>Aspen</strong>Tech<br />

indicates that this model is slightly more accurate than the Twu model for<br />

light and medium boiling petroleum components, while the Twu model is<br />

superior for heavy fractions.<br />

For pseudocomponents, the API model is used:<br />

Where:

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