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In a message dated 10/21/2002 7:07:07 AM Central Daylight Time,
n268bl@charter.net writes:
> Subj: [FlyRotary] Re: Electric Water Pumps
> Date: 10/21/2002 7:07:07 AM Central Daylight Time
> From: n268bl@charter.net (Bill Eslick)
> Sender: flyrotary@lancaironline.net
> Reply-to: <A HREF="mailto:flyrotary@lancaironline.net">
flyrotary@lancaironline.net</A>
> To: flyrotary@lancaironline.net
>
> ..............................So to remove the waste heat from the engine,
> operating at 180 horsepower,
> there needs to be a 47 Degree temperature rise across the engine and a 47
> Degree temperature drop across the radiator.
> ..................................
>
> ***************************************************
>
> This may not be the case in actual practice. I estimate my engine at about
> 140 HP at this point, and running this thru the equations gives me about a
> 36 degree drop required. (Did I do that correctly?)
>
> I can climb out on 100+ degree days and the temp drop across my (GM) cores
> is only 10-15 degrees. Cooling is stable at that point at around 190
> degrees. In my first 100 hours at many temps and altitudes, the drop is
> always around 10 to 15 degrees.
>
> I am using the CHT probes of my EIS clamped to the exit tubes of the cores
> to get these temps. They are wrapped with firesleeve to ward off other
> sources of heat.
>
> Bill Eslick
>
>
>
> >> Homepage: http://www.flyrotary.com/
>
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Your measurements of the delta T indicate that you have much greater flow
rate than 80 liters per minute. A higher flow rate means that the delta T
will be less. Your arithmetic is correct, at 80 liter/min flow, you should
expect 36 degree delta T. Since you are getting 15 degree delta T, your flow
rate is about
36*80/15 = 192 liter/minute, or 50 gallons/minute (which is about what
Powersport found they needed).
Everyone please bear in mind that I have nothing against Electric Water
Pumps, but I firmly believe in things like thermodynamics, heat capacity, and
pump pressure curves. Too many engineering courses I guess -- I have only
used the data published by Davies-Craig and Mazda in my calculations.
Bill Schertz
KIS Cruiser #4045
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