Air density
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The pressure is 80–150 kPa and the temperature is 10–110 degrees. How can the density of air be calculated? Is it D = PW (molecular weight) / RT? ? Should I still check the reference books?
Air is a mixed gas, and it is more accurate to calculate it using a formula.
It’s of course better to have a book from which one can look things up; when that’s not possible, one has to use the formula for rough calculations, after all, this formula is applicable to ideal gases.
It is best to perform the calculations using equations or programs; the ideal gas law can only be used for estimation.
At such low pressure, with a temperature that isn’t particularly low (100 degrees), the ideal state equation can be used perfectly well, and the error will not be significant； It’s possible to do it by hand; you can also use simulation, and the error won’t exceed 1%
Check out industrial gases; having consistent information is helpful for design work
Air density range: 80, 80, 150, 150. Pressure: 10, 110, 10, 110. Temperature: 1.166, 0.862, 1.425, 1.052. Density
It can be estimated using the PV-T formula. If it is for studying aerodynamics or requires very precise density values. It’s better to check the manual or use professional simulation software.
When calculating using the ideal gas law, it is also necessary to take into account the air compressibility factor, as air is a mixed gas and therefore an ideal gas is not.
For dry air, it can be calculated in this way
It’s not me who’s adding water; you can just check the table directly for that