Air  Prandtl Number
Prandtl number for air vs. temperature and pressure.
The Prandtl Number  Pr  is a dimensionless number approximating the ratio of momentum diffusivity (kinematic viscosity) to thermal diffusivity  and is often used in heat transfer and free and forced convection calculations.
The Prandtl number can for calculations be expressed as
Pr = μ c _{ p } / k (1)
where
μ = absolute or dynamic viscosity [kg/(m s)], [lb _{ m } /(ft h)]
c _{ p } = specific heat [J/(kg K)], [Btu/(lb _{ m } ^{ o } F)]
k = thermal conductivity [W/(m K)], [Btu/(h ft ^{ 2 } ^{ o } F/ft)]
Below, Prandtl numbers for air at varying temperatures and pressures are given in figures and tables .
See also other properties of Air at varying temperature and pressure: Density and specific weight at varying temperature , Density at varying pressure , Diffusion Coefficients for Gases in Air , Specific heat at varying temperature and Specific heat at varying pressure , Thermal Conductivity , Thermal Diffusivity , Properties at gasliquid equilibrium conditions and Air thermophysical properties at standard conditions and Composition and molecular weight ,
as well as Prandtl number of Ammonia , Carbon dioxide , Methane , Nitrogen , Propane and Water .
Air Prandtl number at 1 bara pressure, temperature given as °C or °F:
Air Prandtl number at varying temperatures and constant pressures, SI and Imperial units:
Air Prandtl number at 1 bara pressure, temperature given as °C or °F:
Temperature  Pr  Temperature  Pr 
[°C]  []  [°F]  [] 
100  0.734  150  0.733 
50  0.720  50  0.719 
0  0.711  0  0.714 
25  0.707  60  0.709 
50  0.705  75  0.708 
100  0.701  100  0.706 
150  0.699  200  0.701 
200  0.698  300  0.699 
250  0.699  400  0.698 
300  0.702  500  0.700 
Air Prandtl number at given temperatures and 1, 5 10 and 20 bara pressure:
Temperature  Prandtl number at given pressures  
[K]  [°C]  [°F]  1 bara, 14.5 psia 
5 bara, 72.5 psia 
10 bara, 145 psia 
20 bara, 725 psia 
60  213.2  351.7  4.138  4.153  4.170  4.187 
80  193.2  315.7  1.7  2.252  2.259  2.269 
100  173.2  279.7  0.780  0.898  1.783  1.770 
120  153.2  243.7  0.759  0.806  0.890  1.360 
140  133.2  207.7  0.747  0.773  0.812  0.923 
180  93.2  135.7  0.731  0.743  0.759  0.792 
200  73.2  99.7  0.726  0.735  0.745  0.769 
220  53.2  63.7  0.721  0.728  0.736  0.754 
240  33.2  27.7  0.717  0.722  0.729  0.742 
260  13.2  8.3  0.713  0.718  0.723  0.734 
273  0.0  32.0  0.711  0.715  0.720  0.729 
280  6.9  44.3  0.710  0.714  0.718  0.727 
289  15.6  60.0  0.709  0.713  0.716  0.723 
300  26.9  80.3  0.707  0.711  0.714  0.722 
320  46.9  116.3  0.705  0.708  0.711  0.717 
340  66.9  152.3  0.703  0.705  0.708  0.714 
360  86.9  188.3  0.701  0.703  0.706  0.711 
380  106.9  224.3  0.700  0.702  0.704  0.709 
400  126.9  260.3  0.699  0.701  0.703  0.706 
500  226.9  440.3  0.698  0.700  0.701  0.703 
600  326.9  620.3  0.703  0.704  0.704  0.706 
700  426.9  800.3  0.710  0.710  0.711  0.712 
800  526.9  980.3  0.717  0.718  0.718  0.719 
900  626.9  1160.3  0.724  0.725  0.725  0.725 
1000  726.9  1340.3  0.730  0.730  0.730  0.731 
1100  826.9  1520.3  0.734  0.735  
1500  1226.9  2240.3  0.743  0.743  
1900  1626.9  2960.3  0.742  0.742 
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