Title Chapter_3_0114 (1) Humidity Relative Humidity Pascal (Unit) Atmospheric Pressure Pressure 94.2 KB 15
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3. Moist Air Properties and Conditioning Processes

( )tWti 86.13.25010.1 ++= kJ/kga
( ) ( ) ( )( )[ ]2086.13.250101407.0700.1 ++=i = 55.7 kJ/kga

Specific Volume:

Ra = 287 J/kg.K

s

a

a

a

pP

TR

p

TR
v

==

( )( )
( )( )100034.2325.101

15.27320287

+
=v = 0.85 m

3
/kga

(b) In English units, t = 20 F

Humidity Ratio:

Eq. (3-14b)

s

s

a

s

s
pP

p

p

p
W

== 6219.06219.0

at t = 20 F < 32.02 F,

use ps at 32.02 F which is nearly equal by plotting on curve = 0.089 psia

P = 14.696 psia

089.0696.14

089.0
6219.0

=

s
W = 0.0038 lbmv/lbma

Enthalpy:

Eq. (3-20a)

( )tWti 444.02.1061240.0 ++= Btu/lbma
( ) ( ) ( )( )[ ]20444.02.10610038.020240.0 ++=i = 8.7 Btu/lbma

Specific Volume:

Ra = 53.352 ft-lbf/lbm-R

s

a

a

a

pP

TR

p

TR
v

==

( )( )
( )( )144089.0696.14

67.45920352.53

+
=v = 12.17 ft

3
/lbma

In SI units, t = -6.7 C

Humidity Ratio:

Eq. (3-14b)

s

s

a

s

s
pP

p

p

p
W

== 6219.06219.0

at t = -6.7 C < 0.01 C,

use ps at 0.01C which is nearly equal by plotting on curve = 0.00061 Mpa = 0.61 kPa