# Chapter 12 - Properties of Gaseous mixtures¶

## Example 1 - Pg 201¶

In [3]:
#Calculate the partial pressure and specific humidity
#initialization of varaibles
P=15. #psia
T2=70.+460 #R
T1=55.+460 #R
#calculations
pw=0.2141
pA=P-pw
mratio=pA*29/(pw*18.)
mAbym=mratio/(1+mratio)
mwbym=1/(1+mratio)
pg=0.3631 #psia
phi=pw/pg
gamma=1/mratio
#results
print '%s %.2f %s' %("Partial pressure of water vapor = ",pA,"psia")
print '%s %.4f %s' %("\n Specific humidity = ",gamma,"lb vapor/lb air")
print '%s %.2f' %("\n Relative humidity = ",phi)

Partial pressure of water vapor =  14.79 psia

Specific humidity =  0.0090 lb vapor/lb air

Relative humidity =  0.59


## Example 2 - Pg 201¶

In [3]:
#calculate the mass of watervapor per pound of dry air
#initialization of varaibles
rh=0.75
pg=0.5069
inc=10 #in
pA=29.50 #psia
#calculations
pw=rh*pg
p=(29.50+ inc/13.6)*0.491
pA=p-pw
mratio=pw*18/(pA*29.)
#results
print '%s %.4f %s' %("Pounds of water vapor enter the surface per pound of dry air =",mratio,"lb vapor/lb air")

Pounds of water vapor enter the surface per pound of dry air = 0.0163 lb vapor/lb air