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Supercritical gases

Supercritical gases

Supercritical gases

(OP)
Hi there,
I´m looking for a program suited to calculate gas properties in supercritical conditions( 280 bar,700°C). I need it for CO2,CH4, water and it would be perfect also for C2H6 and C3H8.
Do someone know some programme?
At this time I found Prosim, which is also pluggable with excel. I red the tutorials but they are not so clear, where is it possible to find some other tutorials or user´s guide?

Thx

RE: Supercritical gases

Arimans:

All the fluids you mention are defined as to thermo properties (including the supercritical zone) at:

http://webbook.nist.gov/chemistry/fluid/

All the fluid properties can be obtained in tabular format and easily highlighted, copied, and pasted onto an Excel spreadsheet for easy access and databasing.

There are no supercritical gases.  There are only supercritical fluids.  The phase of supercriticality was coined because the fluid is clearly neither a gas or a liquid and needed another identification because of it's unique properties.  You will note that NIST clearly identifies the gas, liquid, and supercritical phase.  I don't believe it enters into the solid phase - yet.


RE: Supercritical gases

(OP)
Thx for your help.
I know that there are no supercritical gases :) , I had this mistake ´cause I was trying to write without grammatical errors... ;)
I already know that site...The problem is that I need to vary both the temperature and the pressure. If I had a programme which calculates automatically the resulting values for each properties, it would be easier than copy manually the tables for each temp and pressure and make an access database plugged with excel.
There is another difficulty, the Nist does not go up to 700°C for each gas, that means I have to interpolate the function and than to use it to complete the database.
I´m sorry, I know I´m not clear and I have so much questions, but I just started with this topic and I do not have so much experience.


Thx

RE: Supercritical gases

Here is a lower cost and easy to use program that incorporates all the lastest data from NIST, GPA, ASTM, ISO ect..  www.winsim.com

RE: Supercritical gases

How accurate do you need to be?

At the stated P+T conditions, you're well removed from the critical region and should be reasonably accurate assuming ideal gas behavior.

Alternatively, you might select one of the compounds as a reference fluid and then apply the "method of corresponding states" to the gas mixture. In other words, at the same Tr and Pr, the compressibility factor should be the same. So, calculate mixture Tr and Pr and then refer to a pressure-enthalpy or Mollier chart for the reference fluid using the same Tr and Pr to obtain real gas density (hence Z) for the reference fluid...which should approximately equal Z for the mixture.

If mixture Tr and Pr are within recommended limits, you could try the BWR EOS as implemented by Dranchuk, Purvis and Robison. You might also refer to "Properties of Liquids and Gases" by Reid, Prausnitz, and Poling.

RE: Supercritical gases

The GPSA book has a PVT chart that you can get all the properties from for pure componets.

RE: Supercritical gases

(OP)
Thanks guy!

We decided to buy the Porsim.
Another problem is that I would develop a program as most flexible as possible, and because of this I need an automatic way to retrieve the fluid´s properties.
Actually I do not know how good it is in supercritical conditions, but I compared the properties´ values taken from NIST with those given by ProSim and they seem to be quite similar.
In few months than we will compare my calculations with the real values measured in our prototype plant.

Thx

RE: Supercritical gases

ANY program you buy should EXACTLY match NIST, since you do not need to do distillations and complex reactions, stay with the lowest cost program, IMHO.

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