radiators for aircraft.  Interestingly, I have never heard it mention by

those who have studied K&M on the topic of cooling. Perhaps it was

overlooked.

 

Generally,  I am a bit cautious ({:>) about interpreting

such techncial stuff - as it is not difficult to draw an incorrect

inference.

However, in this case the authors of the study provide the interpretation

(see attachment)

 

In essence, they make the statement that thicker radiators with closer fin

spacing provides for more heat dissapation into an airstream.  The

refer to the thickness as "L" length of the cooling block (heat exchanger)

and the "D" the hydraulic wetted area spacing (basically related to the fin

area/spacing) .  Re is the Reyonlds number which is smaller with lower

velocity.

 

If removing the highest amount heat per unit of air flow is the criteria; then thick radiators with close fin spacing and slow air flow is the way to go.  When you add the other criteria of fixed dynamic head (pressure), area constraints, drag, and weight; and maybe a few others; that is no longer the case.

 

Parametric studies using fairly sophisticated analytical models that I have seen suggests that for our aircraft applications the optimum lies somewhere in the 2-3” thickness range.  And this of course will depend on some configuration variables.  This is also for an optimally designed radiator.  A optimally designed AC evaporator may be a bit different because it is designed for a different fluid. 

 

Al