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Hi guys,
If you can arrange true *counter flow* you can get the exit air hotter than the exit water. My understanding of Todds setup is that it is similiar to mine -- two evaporator cores, in cross flow arrangement.
With that arrangement, it is *highly unlikely* to get the exit air hotter than the exit water, integrated over the surface of the exchanger. Heat has to flow downhill.
If you use the charts that I had in my article, you can do your own calculations. I used Todd's numbers because he actually measured the flow in the plane cooling loop. My results indicate that it works okay in cool flying conditions, but might be marginal in hot conditions with high power.
Bill Schertz
KIS Cruiser # 4045
----- Original Message ----- From: "Ernest Christley" <echristl@cisco.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Friday, January 14, 2005 12:58 PM
Subject: [FlyRotary] Re: Welcome to the Club was Re: [FlyRotary] Nomore ACRE (for me)
On Fri, 2005-01-14 at 13:22, Bob White wrote:
Here is a link to the analysis Bill Schertz did on Todd Bartram's
cooling system: http://www.acre-media.org/schertz/EWP_analysis.html
Bill's analysis would indicate that Todd's system was marginally
adequate given the assumptions used. Some were overly conservative, and
Todd has reported better results than would be expected from the
analysis.
Is the 'first approximation', that the cooling air will never get hotter
than the exiting water, a good one?
It would seem to me that if you arranged a multipass radiator such that
it entered in the rear and left at the front, the exiting air would be
closer to the temperature of the radiator's hot side.
Homepage: http://www.flyrotary.com/
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