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Aspen Physical Property System - Physical Property Models

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Parameter<br />

Name/Element<br />

VLBROC/1 V i BO<br />

2 Thermodynamic <strong>Property</strong> <strong>Models</strong> 197<br />

Symbol Default MDS Lower<br />

Limit<br />

Upper<br />

Limit<br />

Units<br />

VC x -1.0 1.0 MOLE-VOLUME<br />

VLBROC/2 — 0 x -0.1 0.1 TEMPERATURE<br />

References<br />

S.W. Brelvi and J.P. O'Connell, AIChE J., Vol. 18, (1972), p. 1239.<br />

S.W. Brelvi and J.P. O'Connell, AIChE J., Vol. 21, (1975), p. 157.<br />

Clarke Aqueous Electrolyte Volume<br />

The Clarke model calculates liquid molar volume for electrolytes solutions.<br />

The model is applicable to mixed solvents and is based on:<br />

� Molar volume of molecular solvents (equation 2)<br />

� The relationship between the partial molar volume of an electrolyte and its<br />

mole fraction in the solvent (equation 4)<br />

All quantities are expressed in terms of apparent components.<br />

If option code 1 is set to 1, the liquid volume quadratic mixing rule is used<br />

instead. The default option uses this equation to calculate the liquid molar<br />

volume for electrolyte solutions:<br />

Where:<br />

Vm l<br />

Vs l<br />

Ve l<br />

(1)<br />

= Liquid molar volume for electrolyte solutions.<br />

= Liquid molar volume for solvent mixtures.<br />

= Liquid molar volume for electrolytes.<br />

Apparent Component Approach<br />

For molecular solvents, the liquid molar volume is calculated by:<br />

Where:<br />

xw = Mole fraction of water<br />

Vw *<br />

(2)<br />

= Molar volume of water from the steam table.<br />

xnws = Sum of the mole fractions of all non-water<br />

solvents.<br />

Vnws l<br />

For electrolytes:<br />

= Liquid molar volume for the mixture of all nonwater<br />

solvents. It is calculated using the<br />

Rackett equation.

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