Fluid change (not in a predefined scheme)

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TurCoim
Posts: 10
Joined: Tue Apr 09, 2019 2:55 pm

Mon Apr 29, 2019 2:19 pm

Good afternoon,

thanks to your help in previous topics, I can change the fluid in circulation.

However, as can be seen in the attachments, the modification takes place only if implemented in a Wizard proposed by the software. If starting from this I apply some plant modifications (insert new pipes or heat exchangers) it is not possible to change the fluid.

How could I change it in a plant situation created by me?

Changing the fluid, are required properties from the new fluid. However, for a simple property, such as the boiling point, in the attachments, 5 different parameters are required. What do they refer to? (The boiling point changes with pressure but I don't see how to insert this information)

I thank you in advance for the great support provided.
Attachments
unmodified.PNG
unmodified.PNG (64.9 KiB) Viewed 52 times
parameter fluid.PNG
parameter fluid.PNG (70.69 KiB) Viewed 52 times
modified.PNG
modified.PNG (39.33 KiB) Viewed 52 times

nmarthaler
Posts: 33
Joined: Mon Jun 18, 2018 4:01 pm

Tue Apr 30, 2019 2:04 pm

Hello TurCoim

Try it over the menu results and fluid overview.
Other reason for the problem could be that your loop is to complex.

The other 5 parameters (ex. boiling point) for fluid are only mandatory for the ice storage model. Therefore it is not necessary for your system.

Sunny greetings
Nathanael

TurCoim
Posts: 10
Joined: Tue Apr 09, 2019 2:55 pm

Mon May 06, 2019 12:57 pm

In my model I will use a fluid under pressure, so the state conditions of the fluid are different.

Furthermore, the fluid could vaporize. What would be the logic of entering the parameters in order to insert them correctly? I ask this question because in the catalogs the fluid data refers to environmental conditions.

Thenks in advice for the support

nmarthaler
Posts: 33
Joined: Mon Jun 18, 2018 4:01 pm

Tue May 07, 2019 12:04 pm

Well, if you rally want to simulate phase changes in the fluid and visualized it, you should you Transys. It would be possible with the ice storage model but in your case I don't think it is going to be necessary. Since in real life you are looking for other working temperature and i am sure you will get more or less the same results.
This means in Polysun the phase change (enthalpy) is not calculated.
What is the aim of your simulation?

Sunny greetings
Nathanael

TurCoim
Posts: 10
Joined: Tue Apr 09, 2019 2:55 pm

Thu Jun 13, 2019 5:05 pm

Good afternoon,
the same problem has recurred, as unfortunately unresolved.

I tried to change a predefined fluid with the R245fa, to perform liquid-liquid thermal exchange with a plate heat exchanger.

I would, therefore, have the following technical doubts:

What is the correct procedure for entering the parameters of fluid properties?
What is their thermal and pressure reference?
Can terms related to the temperature be considered negligible?
Why does the vapor pressure in (N / m ^ 2) of the various fluids have such low values?

My organic fluid is under pressure (6.73 bar) therefore it is in liquid conditions at 30 degrees, (value that at atmospheric pressure is steam).

The doubt arose because the vapor pressure of the other fluids is very low compared to mine and in some cases, leaving the value of the water, in the heat exchanger I have the liquid at a temperature higher than the boiling point and / or the cold side (R245fa) at a temperature warmer than that of the warm side.

I thank you in advance for any technical support.
Best regerds

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