Page 145 - Mechanical Engineer's Data Handbook

134 MECHANICAL ENGINEER'S DATA HANDBOOK

Horizontal plate facing downwards

N~=0.25(GrPr)~.~~ GrPr> lo5
for

In-line pipes

3.14.9 Forced convection

Laminar flow in pipe
staggered pipes
k
Nu=3.65 and h=3.65- Turbulent flow over flat plate
d
Let:
L = the distance from the leading edge over which heat
c- td is transferred
C = fluid velocity
For a small temperature difference:
Turbulent flow over cylinder Nu =0.332Re0.5Pr0.33
Generally: Nu = 0.26Re0.6Pr0.3
For gases: Nu = 0.24Re0.6

+L-

For a large temperature difference:
(2°"77
N~=0.332Re~.~Pr~.~~
J?
where: T, =plate temperature, T,=mean fluid tem-
perature.
Turbulent flow over banks of pipes

Generally: Nu = 0.33C,Re0.6Pr0.3
For gases: Nu = 0.30C,Re0.6 Turbulent flow in pipe
In-line pipes: C, N 1 .O kNu
Staggered pipes: C,? 1.1 Heat transfer coefficient h = -
d