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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2503772@logan.com>
Subject: Flat plate - Finned Tube Re: what are they
Date: Sun, 25 Nov 2007 09:22:44 -0500
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  I think the "Flat Plate" type radiator comes closer to what the majority 
of us are using including the evaporator cores than you might think.  The 
tube and fin type like some of the auto transmission and oil coolers use are 
a different beast. A lot of the cheaper tube and find type are simply one 
long serpentine tube with fins attached which is bound to cause the DeltaT 
factor to suffer.  Some of the better one have multiple tubes between two 
side tanks.

 My GM cores has about 14 channels  approx 1/8" thick that channel coolant 
between the two side tanks.  These look more like plates to me - than tubes. 
The louver fins on the GM core are suppose to be the best practical fin 
configuration for heat transfer.  So I think the heat transfer is 
undoubtedly better and suspect the drag is also higher than the finless flat 
plate type.

So while its beyond my capability to prove it, I think there is more 
correlation between the Naca study on thick cores and our cores than you 
might first think.  Besides, there graphs of data shows extrapolation of 
cores only 4" thick, which puts it closer than the 9-16" mentioned in the 
text.  So the only major difference I see is ours have fins and the one's in 
their stuff did not.  Would this enhance or degrade the effects they 
measured?

I think our cores would have enhanced heat transfer and increase core drag 
compared to the study - but, I readily admit just speculation on my part.


Ed
----- Original Message ----- 
From: "Ron Springer" <ron2369@sbcglobal.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, November 25, 2007 2:42 AM
Subject: [FlyRotary] Re: what are they


>I am just a radiator novice, but all radiators that I
> have any experience with have had straight passages
> from front to back between fins. When that is the
> case, most books and reports use flat plate drag
> equations to determine the skin friction and heat
> transfer as a first cut. Now if a flat plate radiator
> is a radiator where flat plate drag equations can be
> used, then I guess I haven't seen a radiator that
> isn't one.
>
> Actually, I take that back. The A/C condenser on my
> car has taken so many rock hits that the leading edge
> of many of the fins are badly bent. I guess some new
> equations will be needed!
>
> Ron
>
>
> --- Ed Klepeis <techwelding@comcast.net> wrote:
>
>> Dear Tracy
>>         I'm with you what are these special flat
>> plate rads. I have built many systems but haven't
>> come across these flat plate rads. I will stand
>> corrected if someone comes up with something. I
>> think what everyone is talking about is a flat plate
>> cooler that is put in the bottom tank on rads to
>> cool trans fluid. I think fluidyne is using them as
>> oil to water oil coolers. I looked into that but
>> didn't like the sealing system they used around the
>> oil inlet/outlet good enough for cars but not safe
>> for aircraft. If anyone has anything to add to this
>> I would be happy to hear about it.
>>
>>
>>             Regards
>>
>>
>>         Ed Klepeis
>
>
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