Microsoft Word - Cengel and Boles TOC _2-03-05_.doc

696 | Thermodynamics

Also,

Therefore,

(c) The reduced temperatures and pressures for both N 2 and O 2 at the initial

and final states and the corresponding enthalpy departure factors are, from

Fig. A–29,

N 2 :

O 2 :

From Eq. 12–58,

TR 1 ,O 2 

Tm,2

Tcr,O 2

160 K

154.8 K

1.03

PR,O 2 

Pm

Pcr,O 2

10 MPa

5.08 MPa

1.97

TR 1 ,O 2 

Tm,1

Tcr,O 2

220 K

154.8 K

1.42

TR 2 ,N 2 

Tm,2

Tcr,N 2

160 K

126.2 K

1.27

PR,N 2 

Pm

Pcr,N 2

10 MPa

3.39 MPa

2.95

TR 1 ,N 2 

Tm,1

Tcr,N 2

220 K

126.2 K

1.74

3503 kJ/kmol

316394  46502 kJ>kmol 4  1 8.314 kJ>kmol#K 21 132.2 K 21 1.02.6 2

qout
 1 hm 1 ,idealhm 2 ,ideal 2 RuTcr 1 Zh 1 Zh 22 m

4650 kJ>kmol

 1 0.79 21 4648 kJ>kmol 2  1 0.21 21 4657 kJ>kmol 2

hm 2 ,ideal
yN 2 h2,ideal,N 2 yO 2 h2,ideal,O 2

6394 kJ>kmol

 1 0.79 21 6391 kJ>kmol 2  1 0.21 21 6404 kJ>kmol 2

hm 1 ,ideal
yN 2 h1,ideal,N 2 yO 2 h1,ideal,O 2

f¬Zh 1 ,N 2
0.9

f¬Zh 2 ,N 2
2.4

f¬Zh 1 ,O 2
1.3

f¬Zh 2 ,O 2
4.0

5222 kJ>kmol

316404  46572 kJ>kmol 4  1 8.314 kJ>kmol#K 21 154.8 K 21 1.34.0 2

1 h 1 h 22 O 2
1 h1,idealh2,ideal (^2) O 2 RuTcr 1 Zh 1 Zh 22 O 2

3317 kJ>kmol

316391  46482 kJ>kmol 4  1 8.314 kJ>kmol#K 21 126.2 K 21 0.92.4 2
1 h 1 h 22 N 2
1 h1,idealh2,ideal (^2) N 2 RuTcr 1 Zh 1 Zh 22 N 2
Therefore,

3717 kJ/kmol

1 0.79 21 3317 kJ>kmol 2  1 0.21 21 5222 kJ>kmol 2
qout
yN 21 h 1 h 22 N 2 yO 21 h 1 h 22 O 2