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I can't understand anybody not pouring over that reporting
(repeatedly) it makes such interesting reading {:>))
However, I have read the report and
I agree the radiators they are discussing have no fins. The report
describes two type cores they tested. One was the flat plate cores
tested for heat transfer and a set of dummy cores made out of copper strips for
testing drag and mass flow. Clearly the only one of interest regarding heat
transfer are the actual flat plate cores.
My interpretation of the flat plates cores are
they are constructed of a stack of flat channels that run from one side
to the other and extending from the front of the core to the rear of the
core. So a stack of hollow, thin plates carrying the heated
coolant which are like 9 - 13" deep (from front of core to rear of core), 1/8"
thick and span across the width of the core.
Attached is a photo of one extracted from
the report - which is clearly quite thick, appears to have side tanks (holes on
each side for coolant?) and a number of plates in the stack. So, at least,
conceptually (with the exception of no fins), the cores do not appear to be
functionally different that my GM cores. A number of stacked plates
running from tank to tank, the plates being approx 1/8" thick and approx 3 1/2"
deep and approx 10" wide - with plenty of fins of course.
They are certainly different in construction, bigger,
thicker, etc than our cores, the data was extrapolated to cores just 4" thick
(deep). So while I agree they are certainly not a direct match, I am
convinced that some of the test results might have some
applicability to air flowing through our cores relative to heat
extraction. After all we are flowing air over heated metal
{:>)
I certainly agree that the drag of our finned radiators
would be much higher, pressure drop greater - but what about the heat extracted
per inch of thickness?.
However, I thought the report might be of
interest because, if was one of the few studies I have come across
addressing the effects of core thickness on the parameters we are
interested in. At least it shows for those cores, that thickness does
contribute significantly to heat rejection.
But, you may be correct - too different to be
applicable.
Ed
----- Original Message -----
Sent: Sunday, November 25, 2007 11:21
AM
Subject: [FlyRotary] Re: what are
they
I don't think you guys are actually reading the NACA paper about these
rads.
The flat plate rads in the paper have NO FINS at all and do not
have multiple layers of flat tubes, only a continuous flat tube from front to
back (as much as 20" !!! ) with NO FINS on the tubes. I have only
seen this type of rad in a museum so I'm not surprised that people are a bit
confused about this. That is why I said this study is not applicable to
our installations.
Ed K. may be correct that a similar core might be used inside water
to oil coolers.
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