1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Thermodynamic Data for Nitrogen

  1. Sep 6, 2012 #1

    boneh3ad

    User Avatar
    Science Advisor
    Gold Member

    Does anyone have a good source of saturation data for nitrogen at low pressures? By low pressures, I mean something along the lines of 0.01 atm.

    Thanks,
     
  2. jcsd
  3. Sep 6, 2012 #2

    Mech_Engineer

    User Avatar
    Science Advisor
    Gold Member

    I was going to recommend NIST's Themophysical Properties of Fluid Systems database, but their saturation data for Nitrogen only goes down to about .125atm.

    Still, judging by the shape of the curve you might consider interpolation if you can't find anything else. Keep in mind we're talking about seriously cryogenic temperatures at those low pressures, probably less than 10K!
     
  4. Sep 6, 2012 #3

    boneh3ad

    User Avatar
    Science Advisor
    Gold Member

    Right. I ran into the same problem as the NIST web book is typically my go-to source as well.

    Extrapolating may provide a reasonable estimate. The point of my query is that for supersonic wind tunnels you can achieve static temperatures that low and if you don't pay attention to the saturation temperature of your gas, you can see liquefaction occur. I am planning on writing a homework problem based on this but was trying to make sure the data was readily available first. Maybe I'll just stick to helium. That is more commonly used anyway.
     
  5. Sep 6, 2012 #4

    Mech_Engineer

    User Avatar
    Science Advisor
    Gold Member

    Well since the saturation temperature of Nitrogen at that low of a pressure is <10K, you shouldn't need to worry about condensation unless you're doing tests in a wind tunnel near absolute zero...
     
    Last edited: Sep 6, 2012
  6. Sep 6, 2012 #5

    boneh3ad

    User Avatar
    Science Advisor
    Gold Member

    Again, you can easily get down into that range in a wind tunnel if you have a high enough Mach number. For example, in a Mach 10 wind tunnel, if you started with your reservoir at room temperature (300K) you would have a static temperature in your test section of 14K. This is why wind tunnels operating at high Mach numbers must have the flow preheated.
     
  7. Sep 6, 2012 #6

    Mech_Engineer

    User Avatar
    Science Advisor
    Gold Member

    It looks like Helium's saturation temperature will be very low, less than 2K if we believe the quick and dirty power series fit interpolation from Excel.

    Looking at the data sets side by side Nitrogen is more difficult to predict than I expected because it's unclear how its properties change at very low pressures. It seems that it would have to asymptotically approach (0.000 K , 0.000 atm) but a simple power series fit doesn't do a very good job representing that... so basically don't listen to me ;-)
     

    Attached Files:

  8. Sep 6, 2012 #7

    boneh3ad

    User Avatar
    Science Advisor
    Gold Member

    Haha, yeah. NIST has data sufficient for helium so I will just use that. Helium is actually used in wind tunnels more often that pure nitrogen anyway, so it is probably a more "relevant" problem.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Thermodynamic Data for Nitrogen
  1. Empirical data (Replies: 15)

  2. Nitrogen Laser (Replies: 1)

  3. Liquid Nitrogen Supply (Replies: 4)

Loading...