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Aspen Physical Property System - Physical Property Models

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Model Type<br />

Chapman-Enskog-Wilke-Lee (Binary) Low pressure vapor<br />

Chapman-Enskog-Wilke-Lee (Mixture) Low pressure vapor<br />

Dawson-Khoury-Kobayashi (Binary) Vapor<br />

Dawson-Khoury-Kobayashi (Mixture) Vapor<br />

Nernst-Hartley Electrolyte<br />

Wilke-Chang (Binary) Liquid<br />

Wilke-Chang (Mixture) Liquid<br />

Chapman-Enskog-Wilke-Lee (Binary)<br />

The binary diffusion coefficient at low pressures is calculated using<br />

the Chapman-Enskog-Wilke-Lee model:<br />

Dij v =Dji v<br />

Where:<br />

The collision integral for diffusion is:<br />

�D<br />

282 3 Transport <strong>Property</strong> <strong>Models</strong><br />

=<br />

The binary size and energy parameters are defined as:<br />

�ij<br />

�ij<br />

=<br />

=<br />

A parameter � is used to determine whether to use the Stockmayer or<br />

Lennard-Jones potential parameters for �/k (energy parameter ) and �<br />

(collision diameter). To calculate �, the dipole moment p, and either the<br />

Stockmayer parameters or Tb and Vb are needed.<br />

Parameter Symbol Default MDS Lower<br />

Name/Element<br />

Limit<br />

Upper<br />

Limit<br />

MW M i — — 1.0 5000.0 —<br />

Units<br />

MUP p i — — 0.0 5x10 -24 DIPOLEMOMENT<br />

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

VB V b — — 0.001 3.5 MOLE-VOLUME<br />

OMEGA � i<br />

— — -0.5 2.0 —<br />

STKPAR/1 (� i/k) ST fcn(T bi, V bi, p i) x — — TEMPERATURE

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