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