CFX – AIR Real Gas – Library

Farbod · July 10, 2015, 15:20

I want to Select material , As AIR Real Gas in CFX .
I searched the Library (PENG ROBINSON . redlich kwong ) , for the Air Real Gas Material , but I couldn’t find that . (I have found many other materials , but not air , which is strange !)

By Selecting The Equation of state as real gas , they are some properties of air which are blank like (Cp , Critical Properties ) . I know I can write the properties by myself .
But I was wondering , why CFX doesn’t provide the properties of this very common material ,Air , in the library .

I appreciate your help with that ,

ghorrocks · July 11, 2015, 07:15

I suspect this is because air is a mixture and therefore not a Peng Robinson material. Try using a multicomponent mixture of nitrogen and oxygen (and the trace stuff if you want super accuracy but are willing to add some more complexity)

Farbod · July 15, 2015, 12:31

Yes , Air can be modelled by Multicomponent .

But , CFX , provide the properties of Air , as Ideal Gas , but not the properties as the Real gas .

So , maybe it is not because of being mixture and there is somewhere inside that I cannot find that .

ghorrocks · July 15, 2015, 20:34

Well keep hunting then. I think my previous post explains exactly why you cannot find it.

July 10, 2015, 15:20	CFX – AIR Real Gas – Library	#1
Farbod New Member Farbod Vakili Join Date: Mar 2015 Posts: 2 Rep Power: 0	I want to Select material , As AIR Real Gas in CFX . I searched the Library (PENG ROBINSON . redlich kwong ) , for the Air Real Gas Material , but I couldn’t find that . (I have found many other materials , but not air , which is strange !) By Selecting The Equation of state as real gas , they are some properties of air which are blank like (Cp , Critical Properties ) . I know I can write the properties by myself . But I was wondering , why CFX doesn’t provide the properties of this very common material ,Air , in the library . I appreciate your help with that ,

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July 11, 2015, 07:15		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	I suspect this is because air is a mixture and therefore not a Peng Robinson material. Try using a multicomponent mixture of nitrogen and oxygen (and the trace stuff if you want super accuracy but are willing to add some more complexity)

July 15, 2015, 12:31		#3
Farbod New Member Farbod Vakili Join Date: Mar 2015 Posts: 2 Rep Power: 0	Yes , Air can be modelled by Multicomponent . But , CFX , provide the properties of Air , as Ideal Gas , but not the properties as the Real gas . So , maybe it is not because of being mixture and there is somewhere inside that I cannot find that .

July 15, 2015, 20:34		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Well keep hunting then. I think my previous post explains exactly why you cannot find it.