Humid Air : Specific heat capacity
Follow us on Twitter
Question, remark ? Contact us at powder.process@protonmail.com
1.
Introduction
2. Humid air specific heat capacity calculation
3. Dry air specific heat capacity
4. Dry air isentropic ratio
1. Introduction
The absolute humidity is calculated from the specific heat of dry air
and the specific heat of water ponderated by the
absolute humidity.
2. Humid air specific heat capacity calculation
How to calculate the specific heat capacity of humid air ?
The specific heat capacity of humid air
at ambient temperature can be calculated thanks to the following
formula :
Cp' = 1005 + 1884*ω
With :
ω =
Absolute
humidity of air ()
Cp' = specific heat of humid air (J/K/kg_dry_air)
3. Dry air specific heat capacity
What is the specific heat of air at usual temperature and pressure
?
The specific heat capacity of air at 300K is Cp = 1.005 kJ/kg/K.
The specific heat capacity of air is varying with the temperature as
reported in the table below :
Temperature in K

Cp in kJ/kg/K

Cv in kJ/kg/K

250 
1.003 
0.716 
300 
1.005 
0.718 
350 
1.008 
0.721 
400 
1.013 
0.726 
450 
1.020 
0.733 
500 
1.029 
0.742 
For air, at ambient temperature k = Cp/Cv = 1.4