Tehnička termodinamika - Kemijsko-tehnološki fakultet

_________________________________________________Drugi glavni zakon termodinamike
b)
Stanje
p
kPa
v
m
3 kg
−1
T
K
1 120 0.669 303
2 1706 0.114 734
3 68.69 1.208 313
4 68.69 1.169 303
R s
ω 3
N = 2
8
, ω 4
O = 2
8 , ω 1
CO = 2
8
R ∑ω
⋅ R
s = i i
R s = ω N ⋅ R + ω ⋅ R + ω
⋅ R
2 N2
O2
O2
CO2
CO2
3 8.314 4 8.314 1 8.314 0.265 kJ kg
−1 K
1
= ⋅ + ⋅ + ⋅ =
−
8 28 8 32 8 44
R ⋅T1
v 1 = = = 0.669 m kg
p 120
1
0.265
⋅ 303
3 −1
R ⋅T4
0.265 ⋅ 303
p4 = = = 68.69 kPa
v 4 1.169
3
p
3 = p4
=
68.69kPa
R ⋅T3
v 3 = = = 1.208 m kg
p 68.69
0.265
⋅ 313
3 −1
Za stanje 2 ne znamo nikakav parametar. Međutim, točka 2 povezana je s
točkom 1 politropom, a s točkom 3 adijabatom. Zato
T
T
1
2
⎛ v
=
⎜
⎝ v
2
1
⎞
⎟
⎠
n-1
→
303 ⎛ v2
⎞
= ⎜ ⎟
T ⎝ 0.669 ⎠
2
1.5−1
T
T
3
2
⎛ v
=
⎜
⎝ v
2
3
κ -1
⎞
⎟
⎠
→
313 ⎛ v2
⎞
= ⎜ ⎟
T ⎝1.208
⎠
2
κ −1
181