Vaisala PTU300 - Other Psychrometric Calculations

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204 _________________________________________________________________ M210796EN-F
Mixing ratio:
w
w
Pp
P
x
-
99.621 
(2)
Absolute humidity:
T
P
a
w
 68.216
(3)
Enthalpy:
x
x
T
h 




 5.2)00189.001.1()15.273(
(4)
The water vapor saturation pressure P
ws
is calculated by using two
equations (5 and 6):



3
oi
i
i
TCT
(5)
where:
T
= temperature in K
C
i
= coefficients
C
0
= 0.4931358
C
1
= -0.46094296 * 10
-2
C
2
= 0.13746454 * 10
-4
C
3
= -0.12743214 * 10
-7



3
1
4
lnln
i
i
iws
bbP
(6)
where:
b
i
= coefficients
b
-1
= -0.58002206 * 10
4
b
0
= 0.13914993 * 10
1
b
1
= -0.48640239 * 10
-1
b
2
= 0.41764768 * 10
-4