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Boiling the fuel? Isn't this the same as trying to re-refine the
gasoline? I think this would cause all sorts of stuff to be distilled out and
clog the fuel line. My $.02
Wendell
To amplify why vapor lock is not an issue here (assuming we
get adequate "tank cooling"), my plan was to cool the oil which gets to a
much higher temp than the coolant. I never got around to finding
out the boiling point of gasoline (anyone here know?) but it was my HOPE that
it would boil which would vastly increase the heat absorbed from the
oil. When the gasoline "steam" returned to the tank, it would
immediately cool and condense to it's liquid state, even if the tank was
almost empty.
Possible flaw is that some components of gasoline might be more volatile
than others, remain in vapor state and escape from the tank vent.
Tracy (still dreaming of drag free cooling)
----- Original Message -----
Sent: Thursday, February 10, 2005 1:13
AM
Subject: [FlyRotary] Re: Heating the
Fuel
Bill & Jim, first and most important, we are all in
agreement that this is
not worth doing. However, you made a couple
of assumptions that are not
quiet accurate. First, the pumps from
Tracy will return 40 gal/hr to the
tank (not 15 - I know, I monitor it in
flight). Second, there will be a
much higher rise in the fuel
temp. Because the fuel would be going so
slowly through the heat
exchanger I would EXPECT it to reach the temperature
of the incoming
coolant, or about a 100 deg rise. This will not cause "the
mother
of all vapor locks" becuase it will be headed back to the tank where
it
will quickly be cooled. How quickly? Quickly enough that the
temp of
the fuel on its way to the engine will be no warmer than
ambient. It
matters not the volume of fuel in the tank (other than
contact area). I
expect it to be the temp
of the fuel going TO the engine to be at ambient -
and adding no
additional risk of vapor lock.
But, the coolant will still only drop
about 3 deg, which is not enough to
make it worth it.
Dave
Leonard
>
> <... For a 10 degree rise in gasoline
temperature you would get a
> 630/12000 = 0.0525 deg F drop in coolant
temperature ..>
>
> OTOH, you'd soon heat your fuel to very
near the coolant temp and have
> the mother of all vapor
locks.
> If that's what you're looking for ... Jim S.
>
>
William wrote:
>
> > Dave,
> > If you burn 10 g/hr,
and are returning 15 g/hr to the tanks, that is
> > 15*6 = 90 #/hr
of gasoline, with a specific heat of ~.7Btu/#, that
> > means you
can transfer 90* 0.7 = 63 Btu/hr/degF rise in gasoline
> >
temperature. Your coolant flow is probably about 25 gallons/minute,
=
> > 25*60 = 1500 gallons/hour = ~1500*8 = 12000 #/hour. For a 10
degree
> > rise in gasoline temperature you would get a 630/12000 =
0.0525 deg F
> > drop in coolant temperature. Doesn't seem
worth it.
> >
> > * note: I used rounded figures for
densities and flow rates and heat
> > capacities. The fact remains
that the flow mismatch makes this not do
> > much.
> >
Bill Schertz
> > KIS Cruiser # 4045
> >
>
> ----- Original Message -----
>
> *From:* DaveLeonard <mailto:daveleonard@cox.net>
>
> *To:* Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
>
> *Sent:* Sunday, February 06, 2005 11:46
PM
> > *Subject:* [FlyRotary] Heating the
Fuel
> >
> > In anticipation of
the new turbo, I am considering ways to improve
>
> coolant cooling. Besides the obvious more
air, more ducting, more
> > radiator; I
have been again toying with the idea of a heat
>
> exchanger. This time coolant to
fuel. The plan would be to use a
> >
typical oil/water exchanger but use fuel instead of oil. I
would
> > use the fuel on the way back to
the tank, and the coolant after it
> > has
already been cooled by the radiator. The fuel would then go
>
> back to the nice metal tank of the RV.
>
>
> > I am looking for input on the
implications of heating the fuel. I
>
> expect it would reach max temps of about 190
(usually a
> > little cooler) but quickly
cool once in the tank. Can the fuel
>
> tolerate that temp without vaporizing? It
will probably expand in
> > the tank but I
don't expect that will occur faster than it is used
>
> up. I have no guess as to what temp will
become steady state for
> > the fuel pumped
out of the tank. My guess is that it will not be
>
> much warmer than normal, but a slight increase
in temp may help
> > with
vaporization.
> >
> > The last
question is how much will it cool the coolant. My hope
>
> is about 10 deg but I doubt it will be quite
that much. I know
> > others have
considered using the fuel to cool (Tracy) and I would
>
> appreciate your thoughts.
> >
>
> Dave Leonard
> >
>
>
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>
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