Metal Foams: A Design Guide

~
P
~
Re 2.6
1000
800
600
400
200
0
0
0.002
0.004
d ~
0.006
0.008
Present
materials
Thermal management and heat transfer 187
0.01
Figure 13.4 The power dissipation plotted as a function of the relative
density, Q, and the dimensionless cell-edge diameter, Qd D d/L
where a is the cell size
a D 1.24d � 3 /Q ⊲13.14⊳
The exponent m and the coefficient have been calibrated by experimental
measurements. They are:
m D 0.4
D 4 ⊲13.15⊳
Some typical results are plotted in Figure 13.3. Pressure drops for other conditions
can be predicted from equations (13.13) to (13.15), again with the proviso
that the fluid flow scaling (13.5) retains its validity. The expected behavior is
illustrated in Figure 13.4.
13.5 Trade-off between heat transfer and pressure drop
For any system there is a trade-off between heat flux and pressure drop. A
cross-plot of these two quantities in accordance with the non-dimensional
0
0.1
0.2
0.3
r ~
0.4
0.5