Predicting Physical Properties 4

[CHD01]

At work I use the program DIPPR to precict physical properties. It is excellent, but is expensive. I have been looking on the internet for a free preferably downloadable program but have not found what I want - has anyone discovered something they would recommend? The more you learn, the less you are certain of.

 

[DeltaCascade]

What physical properties are you looking for ("mechanical for constructin materials or chemical for process fluids"?)
Good luck

 

[CHD01]

chemical for fluids and vapors

density, specific heat, latent heat, MW, viscosity, heat of combustion, flammability limits, flash point, and surface tension. In english units preferably and with Antone constants and formula.

In other words as near to DIPPR as I can get without putting out $1000 for a single licence. The more you learn, the less you are certain of.

 

[rbcoulter]

I have gone through the same problem.
DIPPR is very expensive, and just about anybody else that has something related is selling it at a high price.
The best thing I could find is the book
"The Properties of Gases and Liquids" Fifth Edition
by Poling, Prausnitz, and O'Connell. (About $80 from Amazon)
It has nearly all estimation methods laid out in very good detail with very handy tables.

 

[kbander]

Are you looking for pure component data only, or are you also interested in pseudocomponents? There is a lot of published literature for estimating critical properties, densities, viscosities, etc of pseudocomponents.

For pure components, Properties of Gases and Liquids is excellent as already pointed out. I also have a book by Yaws called Physical Properties that is a great reference for some common compounds.


Regards,


Bob

 

[Lew9b]

I assume you want a mathematical routine for calculating properties of mixed gases. I found a site claiming to have something to use in Excel.
The site is called xlfunctions.com as I recall. The price is fair. It costs $190 as I recall. I want it, but I wanted to hear from someone as to how easy it is to use and how good it is before I spend any money. Sounds like I am being cheap, but I have bought too many things that don't really work.
I work with gas compression, so I need the physical properties like specific heats and densities and compressibilities. Thanks, Lew9B

 

[Guidoo]

Did you already try this link:

http://www.cheresources.com/physinternetzz.shtml

Amongst other links, the site contains a spreadsheet and an Excel Add-in that can be used to estimate the properties you're looking for. The database behind both the spreadsheet and add-in seems to be derived from the above mentioned book "Properties of Gases and liquids". It is only for pure components, though.

 

[bchoate]

There are a couple of packages available that will estimate properties for chemical compounds and have databases of properties for some compounds as well.
G&P Engineering produces PhysProps (about $50)

http://GPEngneeringSoftware.com

Cranium is an excellent package which allows one to draw the structure for estimating properties. There is a demonstration download which will do everything the purchased edition will except save compounds in the application.

http://www.molknow.com

There is something to be said also for collecting a set of methods for properties which are the best available. The normal boiling point is a critical parameter for estimation of many other properties. Joback, Ambrose, and others give fair estimates of the boiling point. There is a newer, more accurate method from Morrero-Gani if anyone is interested.

A third package for estimating properties is "Predict" from Dragon Technology. It is an excellent tool.
Bill Choate

 

[jcd3]

A note of warning about the Excel Add-in mentioned by Guidoo--

It works perfectly in earlier versions of excel, but Excel XP doesn't like it. You'll find that you'll be able to "install" it, but once you exit Excel and restart, the sheet is automatically hidden. I haven't found a way to work around this - I usually install the Add-In, use it for what I need, and then uninstall it before exiting Excel.

Hope this helps!
Jason

 

[Guidoo]

Thanks jcd3. I didn't know about problems with the add-in and Excel XP (we are still in the Excel 97 era...). It may be a better idea to download the Physical Properties Spreadsheet (also from

http://www.cheresources.com/physinternetzz.shtml

). This spreadsheet contains a database with parameters that can be used to calculate properties such as viscosity, heat capacity and vapor pressure. It is quite simple to make a spreadsheet that calculates all these properties using the database, you just have to select the component and the temperature.

 

[CHD01]

Guidoo:

What are the macros for in the Physical Properties spreadsheet and do I need to use them in column's AI through AS?

This sheet is good, but does not have all of the properties I would like to have.

Thanks for the tip on this site for physical properties, it has been helpful. The more you learn, the less you are certain of.

 

[Guidoo]

CHD01 asked me what macros I used. The answer is that I didn't use any macros, but entered formulas directly into the cells. I extensively used the VLOOKUP function.

For example, to find the critical pressure, I used the following formula:

=IF(VLOOKUP($B$4,prop_table,6)=0,"Unknown",VLOOKUP($B$4,prop_table,6)*1.01325)

And to calculate the liquid viscosity, I entered the following formula:

=IF(VLOOKUP($B$4,prop_table,17)=0,"Unknown",10^(VLOOKUP($B$4,prop_table,17)*(1/(T+273.15)-1/VLOOKUP($B$4,prop_table,18))))

Note that the chemical name was entered in cell B4 (using a drop down list), and that the database was on the worksheet named prop_table. Hopefully this helps.

 

[Guidoo]

As another example, I entered the following formula to find the molecular weight:

=VLOOKUP($B$4,prop_table,2)

The VLOOKUP function first looks into the first column of the table named "prop_table". When the component name entered in cell B4 (e.g. "WATER" or "1-BUTENE&quot is found in the table, the function returns the value in column 2 of that table. Column 2 contains the corresponding molecular weights.

Since column 3 contains the freeze points, following formula can be used to find this property:

=VLOOKUP($B$4,prop_table,3)

However, the function can be made more complicated, e.g. to convert the units from Kelvin to °C, or to return "Unknown" in case the database doesn't contain the specific property for the specified component. It would then look as follows:

=IF(VLOOKUP($B$4,prop_table,3)=0,"Unknown",VLOOKUP($B$4,prop_table,3)-273.15)

Good luck!

 

[rbcoulter]

When doing vertical lookup you will get into trouble if you don't enter the exact name as listed in the table.
This often happens. The VLOOKUP can be set to be exact or approximate. Neither one will find, for example, "ethyl benzene" when searching for
"toluene".

 

[Guidoo]

...so that's exactly why I select the component from a dropdown list. Via the dropdown list you can select the components that are in column 1 of the database table. If you can't find the component in the list, you have to think whether it can be found with another name. You can use

http://www.chemfinder.com

to find about any synonym possible for your component.

By the way, toluene is methyl benzene, not ethyl benzene...

 

[rbcoulter]

Guido and bchoate has found some good links to some useful sights that I had not found. I guess the internet is bigger that one can imagine.

Keep in mind though that much of this data is generated by correlated / group contribution methods that may not be sufficiently accurate (depending on use).

One should also check out EPA's website, in particular WATER9, which has a list of 100,000 chemicals, their CAS # and chemical structures in SMILE form. With this info one could calculate (estimate is probably a better word) many chemical properties based on the book
referenced above.

Guido - Thanks. Toluene is methy benzene as you indicated.

 

[25362]

Flash points and flammability limits are easily distorted by the presence of radicals: [HO[·]], [N[·]], [H[·]], [O[·]], [H₃C[·]], which are easily generated from water or from paraffinic hydrocarbons.

These radicals may act as chemical catalysts for combustion and explosions.

 

[avg78]

webbook.nist.gov is a good site to get physical/chemical props of pure components