Large number of header configurations with second
header have been designed and computed. The effects of
the ratio of equivalent diameters (b) on the fluid flow
maldistribution in the plate-fin heat exchanger have
been investigated. Fig. 8 displays the relation of the flow
nonuniformity (S) with the ratio of equivalent diameters
(b) at different Reynolds numbers (Re), i.e. different inlet
mass flow rates. It is found that the second headers
equivalent diameter (U1;out) has an optimum value to
improve the fluid flow distribution in the plate-fin heat
exchanger. Either larger or smaller value will decrease
the improvement. The best arrangement of header
configuration is to keep the parameter b ¼ 1, namely,
U1;out=U1;in is equal to U2;out=U2;in, at which the fluid flow
distribution in the plate-fin heat exchanger is more
uniform. Moreover, the greater Reynolds number may
results in a serious flow maldistribution as shown in
Fig. 8.