BWR equation of state 2

[sdra2]

Does anyone know where I might find a worked example using this specific EOS? I have made a spreadsheet for using it to calculate thermodynamic data (I am not a thermo guy, by the way) but the answers it gives me don't appear to make sense. I'm only really hunting for a mistake in my spreadsheet, but I'm struggling to do so without something to compare it against. I have had a good google at it, but can't find anything!

 

[vpl]

it might help to spell out your abbreviations as there are people from all different disciplines.

Also, since you state you're wanting to check for a mistake in your spreadsheet you might want to (1) provide the equation you're using (in Step 2, Process TGML will give you codes for including various symbols), (2) provide your input conditions, and (3) provide your answer.

Or you could just upload the spreadsheet by using the link to Engineering.com (see Step 3: Attachment)

Patricia Lougheed

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[sdra2]

Hi

Sorry for the lack of information.

I am trying to use the Benedict-Webb-Rubin equation of state to work out properties for n-Pentane.

My reasoning for thinking that my spreadsheet is wrong is as follows:-

* Density of air @ 20 deg C and 1 atmosphere is approximately 1.2 kg/m3.

* Specific gravity of n-Pentane is 2.49 (so density = 2.49 x that of air = 3kg/m3?).

* If I enter 3 kg/m3 as the density and 20 deg C as the temperature (293.15 Kelvin) for n-Pentane, shouldn't I expect the pressure to be 1 atmosphere? Instead I get 11.69 bar absolute.

Apologies if I've done something really stupid folks!

 

[vpl]

Thanks for the further information sdra2! Just so you know, I'm in the nuclear field and, to me, "BWR" means "boiling water reactor" -- totally different then "Benedict-Webb-Rubin." I was trying to figure out which of the many equations describing the nuclear reaction you were wanting.

Patricia Lougheed

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[dcasto]

here's my old basic program in English units. It solves for "z" using BWR. you can see the eight constants and the Alpha/beta constants for the list of compounds.

 

[sdra2]

Thanks dcasto

I'll have a good look through that.

 

[Latexman]

I find if I work a problem by hand it helps me write and troubleshoot a spreadsheet much better than just typing away at it.

Good luck,
Latexman

 

[sdra2]

I have used the same spreadsheet, but with different constants for working out properties for methane to check its workings for a textbook problem. It gives the same answer as the textbook but with a small discrepancy.

I used constants for n-pentane from the same text and I'm pretty sure now that one or more of these must be wrong in the text.

(Hopefully) I can use the info dcasto gave me and convert it to mass rather than mol basis, and then SI rather than English units.