Paul,

Some friends and I were discussing the virtues of various HX fluid flow
schemes. I could tell them how some various designs operated, but I was
unable to discuss them comparatively.

Q1: Of the options in the attachment, assuming they all have the same amount
of core, how do you rate them comparatively in cooling and why?

Q2: Would your rating be the same regardless of the fluid?

Thanks,

Sandy McNabb
Renesis in a Glass Goose

PS: I'm progressing with the "one fold horizontal HX" (see attachments).
This plan has two 17" x 9" x 2.25" cores for 688.5 cu ins. and a 35% wedge
shaped diffuser.

 You have to get that book called Compact Heat Exchangers by Kays and London.
The publisher is in Malabar Fl.

Basically the fluid pumping HP losses are inversely proportional to the
total area of the tubes and to the square of their total length. What ever
it is... it is minuscule compared to the potential cooling system
 drag losses. AKA the drag losses of the air flowing through the core.

Now it is better to speed up the fluid flow in the rad as that maximizes
the heat transfer from the fluid to the metal. In other words a two pass
rad will work better than a one pass rad all other things being equal
including the total fluid flow through the rad.

Now if you take
the two pass rad and put the second pass directly in front of the
first pass, keeping them physically separated, as far as the air
cooling is concerned it will work  better yet for a given rad
frontal area. That is called the counter cross flow configuration.

Configuration D is bad news as you are reheating the part of the
rad that you just cooled off.

The bottom line is: keep the temperature difference between the
metal and the air, in every cubic MM of the rad, as high as possible.
That means run the two rads in parallel and not in series as far
as the fluid plumbing is concerned.

As you can see there are many interrelated factors in HX's.
Make one factor better and something else will get worse.
The questions are: how much better and how much worse.

Thats why I wrote the book :)

Paul Lamar still in Aus