kg ,μ=105.376×10Pa?s,ρ==797.771 v = 0.0012535 kg m3
v
m
De1V2ρ A1
Re1 = = 4.921×10 ,V2 = V1 = 1.352 m s
5
2 ?6
??10? ?
1 ? ε
6 ? ∵ f = 0.0055 1 + ?
? 20000 + ?? ? ?? D Re ? 3
μ
De2V2ρ 5
Re2 = = 2.559 ×10
μ
A2
ε = 0.0015
∴ f1 = 0.0145, f2 = 0.0150
2
L1 ρV1 2 L2 ρV2
ΔPf = ΔPf1 + ΔPf2 = f1 ? ? + f2 ? ? De1
= 20675Pa
13:14:49
2 De2 2
习题讲解 33
出口温度300℃
流× (13 × 10 ) × 5 = 0.5294 kg
量 W = 797.77 × 4
a).试验段出口至换热器入口：
?2 5
π
热交换器
t1 = 300C
P = 160b
?63 v1 = 0.0014166 kg μ1 = 89.36 ×10 Pa ? s
kgρ= 705.92 m3 V1 = = 1.528 m s m1 =
1 v1
0
1
试验段
Wv1 4
π 2 d1
5d1V1
Re1 = = 3.018 ×10
v1μ1
13:14:49 习题讲解 34
? ? 0.0015
f1 = 0.0055 + ?1 + ? 20000 × 25? ?
5? 3.018×10? ? 2
L1 ρ1V1
ΔPf1 = f1 = 1516 Pa
d1 2
ΔPel1 = ρ1 g Δz = 6233Pa ΔP=0 1 a
10
6
??
? = 0.0146 ?
?
1 3 ΔP=K
c1
ρ1V1
2 2
2
705.92 ×1.528
= 0.6 × = 494 Pa
2
13:14:49 习题讲解 35