Page 409 - Mechanical Engineers' Handbook (Volume 4)

398 Cooling Electronic Equipment

Table 8 Correlation Factor for Sparse Tube Banks
Number of Rows, N In Line Staggered
1 0.64 0.68
2 0.80 0.75
3 0.87 0.83
4 0.90 0.89
5 0.92 0.92
6 0.94 0.95
7 0.96 0.97
8 0.98 0.98
9 0.99 0.99
10 1.00 1.00

Flow across Arrays of Pin Fins
For air flowing normal to banks of staggered cylindrical pin fins or spines, 28
0.8
v d
c
hd 1.40 1 / 3

p
Nu (64)
k k
Flow of Air over Electronic Components
For single prismatic electronic components, either normal or parallel to the sides of the
29
3
3
component in a duct, for 2.5 10 Re 8 10 ,
Nu 0.446 Re 0.57
(1/6) (5A /6A ) (65)
0
n
where the Nusselt and Reynolds numbers are based on the prism side dimension and where
A and A are the gross and net flow areas, respectively.
n
0
Table 9 Values of the Constants C
and n
in Eq. (63)
S T S T S T S T
x T 1.25 x T 1.50 x T 2.00 x T 3.00
d 0 d 0 d 0 d 0
S L
x L
d 0 C
n
C
n
C
n
C
n
Staggered
0.600 0.213 0.636
0.900 0.446 0.571 0.401 0.581
1.000 0.497 0.558
1.125 0.478 0.565 0.518 0.560
1.250 0.518 0.556 0.505 0.554 0.519 0.556 0.522 0.562
1.500 0.451 0.568 0.460 0.562 0.452 0.568 0.488 0.568
2.000 0.404 0.572 0.416 0.568 0.482 0.556 0.449 0.570
3.000 0.310 0.592 0.356 0.580 0.440 0.562 0.421 0.574
In Line
1.250 0.348 0.592 0.275 0.608 0.100 0.704 0.0633 0.752
1.500 0.367 0.586 0.250 0.620 0.101 0.702 0.0678 0.744
2.000 0.418 0.570 0.299 0.602 0.229 0.632 0.198 0.648
3.000 0.290 0.601 0.357 0.584 0.374 0.581 0.286 0.608