Thermodynamic properties of gas mixtures
Thermodynamic properties of gas mixtures
(OP)
Hi,
I can't find anything to calculate the thermodynamic propertis of gas mixtures, like:
Butane, propane, pentane, ethylene, methane, hydrogen, etc.
Is there any website where i can do this? Can anyone help me?
I can't find anything to calculate the thermodynamic propertis of gas mixtures, like:
Butane, propane, pentane, ethylene, methane, hydrogen, etc.
Is there any website where i can do this? Can anyone help me?





RE: Thermodynamic properties of gas mixtures
I can recommend several software packages but they are all expensive - but worthless if you dont understand thermodynamics.
Best regards
Morten
RE: Thermodynamic properties of gas mixtures
You are suposing i don't understand thermodynamics....maybe not so good as yours.
That's why i use forums...to ask for stupid ans basic questions...
I don't use any HYSYS software or something like that because i'm not a process engineer or chemical...i'm a mechanical that often needs to solve problems that i usually don't need and thats why i come to ENG-TIPS...otherwise i wouldn't.
Thanks anyway.
RE: Thermodynamic properties of gas mixtures
Let you look here: NIST
I believe it is exactly what you seek.
Good luck,
Latexman
RE: Thermodynamic properties of gas mixtures
I know NIST and i am using it now, but what about mixed components?
Can i integrate them through molar basis (say %) and obtain an average value of a mixture?
RE: Thermodynamic properties of gas mixtures
Best regards
Morten
RE: Thermodynamic properties of gas mixtures
My answer was not intended to be ofensive.
What i was trying to say was that the explanation for my problem is only thermodynamics, you can post it because i will understand. Of course if it is chemical i may not understand it... (or maybe yes). You can't assume that i will not understand it because that is a "non post". If you think that it will be complex, give for example a site or book to consult and to see how complex it may be.
Thanks anyway.
RE: Thermodynamic properties of gas mixtures
And of course this task is generally not that simple as using the weight or molar composition. Specific density and heat capacity are easily obtained that way, but other properties like viscosity, critical properties, etc., require special treatment.
By being more specific on which properties you need you could get more help.
prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads
RE: Thermodynamic properties of gas mixtures
http://www.nist.gov/srd/nist23.cfm
RE: Thermodynamic properties of gas mixtures
Thanks!
RE: Thermodynamic properties of gas mixtures
k=ΣyikiMi1/3/ΣyiMi1/3
where y is a mole fraction and M a molecular weight.
prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads
RE: Thermodynamic properties of gas mixtures
I will try!
RE: Thermodynamic properties of gas mixtures
there is a free copy for personal use, see www.prode.com,
features are comparable to those of simulators.
RE: Thermodynamic properties of gas mixtures
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
RE: Thermodynamic properties of gas mixtures
differently from Nist it works with a database with properties of many pure fluids (which you can edit) and thermodynamic packages which you select for the different calc's (phase equilibria, enthalpy, entropy, volume),
In my opinion Nist or GERG models (available in products as Refprop and Prode) are probably the best for properties of pure fluids (since thay include many specific parameters tuned on each fluid) ,
for mixtures things are more complex,
GERG is accurate but it includes only a limited number of fluids (about 20),
for enthalpy, entropy (and related properties as cp) the std. approach is based on evaluation of departures with a EOS, the advantage being that properties are available for all the fluids in database (Prode has about 1700 components).
Finally there is phase equilibria,
in this field Prode has features comparable to much more expensive simulators.
For my usual applications, separations, fluid properties, compression etc. Prode works just fine and I can easily recommend it.
RE: Thermodynamic properties of gas mixtures
I've downloaded PRODE and i'm starting to use it.
chemlite,
You've said that prode has 1700 componentes, but i've opened it in excel and i only can see 30 or 40...can you help me?
I know that there are some formulas to calculate some properties like Cp, enthalpy, thermal cond., etc, and they are mentioned in PRODE. They are function of some fixed values: a,b,c,etc.
Can anyone refer some book where i can find this parameters, so i can calculate the properties on my own?
Thanks to all!
RE: Thermodynamic properties of gas mixtures
the free version of Prode Properties includes about 60 components (1700 components are available in commercial versions)
however you can add components (I did that for the purpose of testing before to purchase a license).
As said the database includes for each component the parameters (up to 5) for temperature dependent correlations for the different properties as enthalpy, viscosity etc. , for enthalpy, entropy, cp the software calculates departures according selected EOS (there are several available).
I would recommend "The properties of gases & liquids" by Reid, Prausnitz, Poling as a good reference to these matters.
If you wish to calculate directly the properties (not with Prode) then the book includes a limited database for more than 200 chemicals, also there is a Excel compilation available.
Note that you need a good knowledge of thermodynamics to define the models and validate the results, in many cases one prefers to have something tested to utilize (which is the main reason why so many engineers have simulators)
RE: Thermodynamic properties of gas mixtures
Thank you very much for the anwer. It was great! I will look deep in this and try to take a look to that book.
Thanks!
RE: Thermodynamic properties of gas mixtures