Tehnička termodinamika - Kemijsko-tehnološki fakultet

_____________________________________________Prvi glavni zakon termodinamike
V1
p2
n ⋅ log = log
V2
p1
n =
T
1176.8
log
294.2
log3
2
⎛ p
= T1
⎜
⎝ p
2
1
= 1.26
⎞
⎟
⎠
0.26
logT
2 = log 323 +
1.26
p1
⋅V1
m =
R ⋅T
1
n−1
n
1176.8
log
294.2
T 2 = 430 K 294.2 ⋅ 3
=
= 9. 53 kg
8.314
⋅ 323
29
20.93 1.26 −1.4
1,2
= m ⋅ c ⋅ 2 T1
−
29 1.26 −1
Q n
( T − ) = 9.53 ⋅ ⋅ ⋅ ( 430 32)
Q1,2
= −396.3
kJ
⎡ n−1
⎤ 8.314
9.53 ⋅ ⋅ 323 ⎡
m ⋅ R ⋅T1
⎢ ⎛ p ⎞ ⎥
⎢ ⎛ ⎞
⎢
⎜ 2 n
1176.8
W 1,2 = ⋅ 1 −
⎟ ⎥ =
29
⋅ ⎢1
− ⎜ ⎟
n −1
⎢ ⎝ p1
⎠ ⎥
0.26
⎢
⎝ 294.2 ⎠
⎣
⎦
⎣
Q 1,2
= ∆U
+ W1,2
W1,2
= −1124kJ
∆U
= Q1 ,2 − W1,2
= −396.3
+ 1124 =
727.7 kJ
0.26
1.26
⎤
⎥
⎥
⎥
⎦
Primjer 2.14.
1 kg zraka tlaka 98.07 kPa i temperature 30 °C komprimira se na 980.7
kPa. Treba odrediti v2
, T2
, ∆u
i w1,2
.
99