Update compressor_performance.py

[Meydom]

Hello Daniel,

I´ve tried your code and got several errors caused by the wrong order of magnitude for the molecular weight of air. By dividing it by 10^6 I get 0,02897 kg/mol and therefore the correct value for the specific gas constant R (287,05). Maybe the error is anywhere else on my computer (e.g. version compatibility) , but this was the only way to make it work.

Great thesis and thank you very much for publishing your work. Currently I´m writing my own master thesis and I´d like to use your code for mass estimations for the FC´s, if it´s possible. Somehow I got a weight of 275890 kg for the compressor, when I´m using your default values for the calculation. May I ask you, what did I do wrong?

Best regards
Dominic

[danieljuschus]

Hi Dominic, thanks for your comments! I haven't run this in a while, so I was still on version 2.0.12 of pyromat. After updating it to the latest (2.1.10), the error you describe appeared.

At the top, I tell pyromat to use only the base units, because I don't like working with kmol etc.:

pm.config["unit_energy"], pm.config["unit_molar"], pm.config["unit_pressure"] = "J", "mol", "Pa"

In the old version, this worked fine, because I was getting 0.0289 (kg/mol) from air.mw(). Now, I get 28964 (g/kmol?).

I have opened an issue in pyromat about this: chmarti1/PYroMat#39

Regarding this PR, could you please also add a comment after the line, to clarify why it's being divided by 1e6? Then as soon as pyromat's problem is fixed we can revert it again.

Regarding the high mass, perhaps this is another unit problem? What if you just run compressor_mass.py? You should get 19.99 kg. The compressor model is far from perfect, but it should give results that are in the right order of magnitude.

Yes, you're welcome to use my thesis as a reference. I have improved the model in many areas since handing it in, but I'm not allowed to share those unfortunately. We might publish a paper about them instead, but that might take a while.

[danieljuschus]

There is a new version (2.2.0) of Pyromat, where this has been fixed. Could you please check if it works for you?

[Meydom]

They fixed the issue with the wrong order of magnitude of the molecular weight, but with Pyromat Version 2.2.0 and 2.2.1 I get a new error about the wrong range of temperature.

[danieljuschus]

Sorry for the late reply. Seems like an error with pyromat, I've opened an issue for it: chmarti1/PYroMat#52.

[danieljuschus]

Fixed with 1c6de3d. Therefore I'm closing this PR.