Comprehensive list of air properties

[dgt32]

Im looking for a comprehensive list of thermal air properties. I'm used to using ones in the back of textbooks that have values every 25C or so, and extrapolating in between. Does anyone know if a more thorough/comprehensive list is available for free?

 

[Latexman]

Have you looked at

https://www.nist.gov/

They have a ton of stuff.

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water

 

[Iomcube]

dgt32
Will recommend CoolProp addin for Excel (google it)

 

[racookpe1978]

I used this table from EngineeringToolbox site, then developed 10 "best-fit" 2 or 3 order polynomials for each thermodynamic property from -73 C to +50 deg C. (But I was not interested in any higher temperatures.)

https://www.engineeringtoolbox.com/dry-air-properties-d_973.html

My spreadsheet read the specific temperature of each case, then calculated the thermo property (density, heat coef, resistance, viscosity, or whatever) for that specific temperature.

Caution! Few of the properties are even "near-linear" at even a limited temperature span near 0.0 C, so I did have to use best-fit polynomials for every case. Assuming a simple constant value across any but the smallest temperature range is even worse.


I'll try to look up the equations - they may be on this computer.

 

[racookpe1978]

For example, the best-fit curve for the specific heat of air at 1 atm for Temp (deg C) from -100 to +125 deg C is a cubic polynomial:
y = 1.003774 + 0.00003364221*T + 2.572793e-7*T^2 + 6.477078e-10*T^3

But the Thermal Conductivity over the same temperature range appears linear:
y = 0.007870303*T + 2.392981

But a quadratic polynominal fits better:
y = 2.411626 + 0.007979624*T - 0.000003769697*T^2

 

[racookpe1978]

Density is also a little better match as a 3rd order polynomial than a quadratic:

y = 1.289094 - 0.004779697*T + 0.00002030836*T^2 - 6.379363e-8*T^3

 

[racookpe1978]

Dynamic Viscosity fits a quadratic adequately, so you can see each value fits a different curve:

y = 1.714783 + 0.005004539*T - 0.000004127273*T^2