Thermodynamic Data for Nitrogen

In summary, the conversation discussed the search for a good source of saturation data for nitrogen at low pressures, specifically 0.01 atm. NIST's Thermophysical Properties of Fluid Systems database was recommended, but it only goes down to about 0.125 atm. The suggestion was made to consider interpolation at seriously cryogenic temperatures and extrapolation may provide a reasonable estimate. The purpose of the query was to ensure the availability of data for a planned homework problem based on supersonic wind tunnels. Helium was suggested as a more commonly used alternative due to its lower saturation temperature. The difficulty in predicting nitrogen's properties at very low pressures was also discussed.
  • #1

boneh3ad

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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,
 
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  • #2
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!
 
  • #3
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.
 
  • #4
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...
 
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  • #5
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.
 
  • #6
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 ;-)
 

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  • #7
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.
 

What is thermodynamic data for nitrogen?

Thermodynamic data for nitrogen refers to the collection of physical and chemical properties of nitrogen, such as its enthalpy, entropy, and heat capacity, at various temperatures and pressures. These data are used to understand and predict the behavior of nitrogen in different environments.

Why is thermodynamic data for nitrogen important?

Thermodynamic data for nitrogen is important because it allows scientists and engineers to design and optimize systems and processes that involve nitrogen. These data help in making calculations and predictions, as well as in understanding the fundamental properties of nitrogen.

Where can I find thermodynamic data for nitrogen?

Thermodynamic data for nitrogen can be found in various sources, such as scientific journals, textbooks, and online databases. Some common sources include the NIST Chemistry WebBook and the CRC Handbook of Chemistry and Physics.

How is thermodynamic data for nitrogen measured?

Thermodynamic data for nitrogen is typically measured through experiments, using techniques such as calorimetry, thermogravimetry, and spectroscopy. These experiments involve controlling the temperature, pressure, and composition of nitrogen and measuring its properties at different conditions.

What is the unit of measurement for thermodynamic data for nitrogen?

The most common unit of measurement for thermodynamic data for nitrogen is the SI unit, which includes joules for energy, kelvin for temperature, and pascals for pressure. However, other units, such as calories and atmospheres, may also be used in some sources.

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