7 replies to this topic

[JaiEdi]

I have designed a simple single stage nitrogen vapour compression refrigeration cycle. Is Peng Robinson a suitable fluid package to work with in UniSim? 

 

 

Similarly is Peng robinson sufficient for a propylene, ethylene, methane refrigeration cascade? 

 

How could I justify this if it is the case? 

[breizh]

Hi,

Take a look at this thesis , you may find pointers :

http://ethesis.nitrk...lication_detail

 

Google or your favorite search engine should be your ultimate resource.

 

Good luck

Breizh

Edited by breizh, 05 March 2021 - 06:38 AM.

[latexman]

I use Aspen Plus, not UniSim.  Aspen Plus has a Property Method Selection Assistant, or "Methods Assistant" for short.  Does UniSim have similar for you to use?

 

If you had given all components and the range of T and P, I could have relayed what Aspen "Methods Assistant" said.

Edited by latexman, 05 March 2021 - 07:46 AM.

[JaiEdi]

That could be helpful so do you need the composition and range of T and P across the cycle?

I use Aspen Plus, not UniSim.  Aspen Plus has a Property Method Selection Assistant, or "Methods Assistant" for short.  Does UniSim have similar for you to use?

 

If you had given all components and the range of T and P, I could have relayed what Aspen "Methods Assistant" said.

[ChEf]

PR or SRK with LK for ethalpy should be fine.

[breizh]

https://sutherland.c...tySelection.pdf

 

hi,

Consider the link above which confirms the package used in the thesis I forwarded to you .

Read Bob Seader's recommendation for cryogenic : PR and BWRS 

 

Good luck

Breizh 

Edited by breizh, 06 March 2021 - 05:50 AM.

[latexman]

 

That could be helpful so do you need the composition and range of T and P across the cycle? 

 

 

 

Let's make it easy.  List the components, and the lowest and highest T and P in your simulation.

[Pilesar]

You want to use an Equation of State (EOS) for systems of the components you listed. An EOS is designed to calculate the effective partial pressure (fugacity) of the components as they somewhat deviate from acting as an ideal gas. Peng Robinson is a good choice as would be SRK. An EOS has accuracy problems when used to calculate liquid density. Consider using Rackett or Costald for better liquid density calculations. It should be easy enough to try other thermo methods after your model is complete to see how much accuracy risk you have in method selection.