Propane EFI - part duece

[Franc Buxton]

espen hilde wrote:
> 
> Great thinking Greg!
> im  thinking of how long it will take to heat the propane up after start.
> Espen
> 
> Greg Hermann [SMTP:bearbvd at cmn.net] skrev 3. juli 2000 03:18:
> > >In the current spirit of KISS, I want to keep this butt simple.
> > >
> > >Propane in a tank boils at -43f - but will remain liquid as the pressure
> > >builds up.  Therefore, liquid propane's pressure varies wildly as to temp -
> > >requiring a liquid pump, cooler and return system.
> > >
> > It is entirely possible to do liquid propane butt simple!
> >
> > Use a tank with a liquid feed line--which is what all automotive propane
> > fuel tanks have anyway, and use engine coolant to (indirectly) warm the
> > propane TANK to a controlled temperature (which will also be a controlled
> > pressure).Then run the liquid line through a liquid to ambient air cooler.
> > THEN (after the cooler) regulate the pressure of the liquid line to
> > whatever level you want. Be a good idea to include (fixed orifice, very
> > small will do) return bleeds at any high points in the plumbing to return
> > any vapor bubbles to the top of the tank.

	Er, has anybody seen what happens to a tank of propane when it is
heated to around (I believe) 100 deg. Celsius? The idea of actually
_heating_
the stuff doesn't appeal to me, or indeed to any firefighter I know!
OK, you
could control the temperature to lower than that, but even the
extremes of
ambient start to get a bit hair-raising, especially in an enclosed
space under a
hot vehicle. I suspect some kind of cryogenic cooling might instead be
in order.
Does the word 'expensive' now come to mind? Also, I think the
pressure/
temperature curve is extremely non-linear (almost exponential), which
will
make it very difficult to control.

	(I believe 100 deg C is what is called the 'critical temperature' for
propane, above which it will _not_ remain liquid under any
circumstances, and
fairly suddenly begins to obey the ideal gas laws, resulting in a
_huge_ rise
in pressure - enough to rupture the tank if it's not _very_ well
protected
with release valves. I may have the details wrong here, but I have
seen film
of the resulting fireball, which can fry everyone for several hundred
metres
around!)

	Just my little contribution!

	Best regards,
		Franc.
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