5 replies to this topic

[kasri]

Dear sirs,
Please guide what is the use of quality -1 and quality-2 curve in phase envelope in Hysys.
How to use this.
Regards,
Kasri

[PaoloPemi]

I am not familiar with your simulator and I may be wrong but I guess that quality means a specification (for example a line at specified liquid fraction), this is useful when plotting a phase diagram, see for example "http://www.prode.com...seenvelope.htm" for a free sofware

[Chellani]

... quality means a specification (for example a line at specified liquid fraction),

Pretty true, except it is vapor fraction (VF) rather than liquid fraction. Providing input for quality would give you flash results between bubble point (VF=0) and dew point (VF=1).

[Technical Bard]

If you wanted to know the range of conditions when a given percentage of your stream has condensed or vapourized, this is a useful tool...

[tgronn]

Old topic, but just what I was interested in.

Does this mean that setting quality to 0.1 equals 90% by volume?
Is it possible to change the basis, for instance to % by mole?

[PaoloPemi]

generally you solve phase equilibria for a specified molar fraction of gas or liquid phase,
(at least my copy of Prode Properties does that but different tools may add some other features)
for real fluids you must consider Z (compression factor) or equivalent parameter when converting,
for example to convert component i in the mixture from mole fraction to volume fraction
xvi = zi * xmi / SUM(zi*xmi)
hoping this helps.

Edited by PaoloPemi, 23 October 2012 - 11:12 AM.