1 reply to this topic

[nastaran]

Hello Dears,
as you know when we want to define a new heprothical we need at least two properties(Mo;ecular wight and density)
can we define a heprotical with only molecular weight and viscosity or not?

[joerd]

No, you need to supply properties that allow estimating the critical properties which are used in the equation of state. I quote from the Simulation Basis manual (v2004):

Minimum Information Required
If the hypothetical component is defined as a hydrocarbon, the
appropriate default correlations can be used to calculate its
critical properties or any other missing information. Its
interaction parameters are also calculated by HYSYS based on
the estimated critical properties. For HYSYS to estimate the
component's critical properties, a minimum amount of
information must be supplied, as shown in the following table.


Normal Boiling Point | Minimum Required Information
< 700 °F (370 °C) | Boiling Point
> 700 °F (370 °C) | Boiling Point and Liquid Density
Unknown | API & Molecular Weight

The more information you can supply, the more accurate the
estimations are.


Estimation Methods
Prior to installing any Hypotheticals into a Hypo group, examine
the Estimation Methods which HYSYS uses to calculate the
unknown properties for a hypothetical component. You can
specify a estimation method for each property. Click the
Estimation Methods button on the Hypo Group property view.

If you're interested, get a copy of Reid, R.C., Prausnitz, J.M., Poling, B.E., The Properties of Gases & Liquids, 4th edition, McGraw-Hill, 1987.