[Diy_efi] LPG injection

Mike erazmus at iinet.net.au
Sat Nov 23 18:27:16 GMT 2002


Now thats what I wanted to say Greg, but your choice of words
was so much better then my grey matter could stomach ;-)

Anyone looked at methane injection/storage ?

rgds

mike

At 10:53 AM 22/11/2002 -0500, you wrote:
>At 11:48 PM 11/21/02, Derek wrote:
>>"Simply evaporates." You are aware the latent heat of vaporization of
methanol
>>is 3340 BTU/gal? That's a LOT of heat getting taken out of the air. Guess
what
>>propane's is.....only 775. You also will use much less gal/min of propane,
>>as it
>>does have 243% as much horsepower per gallon. Not a problem with
methanol, just
>>spray more. So let's say you are injecting 200HP worth of fuel (propane or
>>methanol) on top of your gasoline.
>>
>>You will get (3340/775)*2.43=10.47 times as much charge air cooling with
>>methanol
>>
>>Do the math before making assumptions.
>
>I HAVE done the math, apparently in a great deal more detail than you have.
>But--one needs to have an understanding of the physics, physical chemistry,
>and thermodynamics as WELL as the math before simply applying the math.
>
>The FACT is that you are not going to get nearly as much "charge air
>cooling" as you call it out of methanal as you claim from the simple
>numbers--because the intake air stream will be cooled sufficiently to reach
>the saturated partial vapor pressure of methanal LONG before all of the
>methanol has evaporated. The REST of the methanol will enter the cylinders
>in (hopefully atomized) liquid form, and the latent heat of vaporization of
>this remaining liquid methanol will act as an internal coolant during the
>compression stroke--reducing peak compression pressure, negative work to
>perform the compression, AND the peak compression temperature. In fact--a
>stoich mixture of methanol has SO much latent heat of vaporization that
>there will STILL be some liquid methanol left at the top of the compression
>stroke, even with a compression ratio in the 12 or 13 to 1 range !! The
>last of the liquid methanol is actually evaporated by the initial heat from
>the flame front when running pure methanol fuel at stoich or richer !!
>
>On the other hand, propane has a MUCH higher saturated vapor pressure, IAT
>for IAT than methanol does, so you are quite likely to get MORE net charge
>cooling from liquid propane than from methanol, regardless of the fact that
>its latent heat of vaporization is less.
>
>AND--talking about latent heat per "GALLON" of any fuel is a joke. At least
>talk in terms of latent heat per pound. Better still, talk about latent
>heat of the fuel for the weight of fuel needed to make a stoich mixture
>with one pound molecular weight (one mole) of intake air. Doing so would
>put things on an apples to apples footing.
>
>Greg
>
>
>>
>>Direct LPG into the ports is nice, good high octane fueling suppliment.
But if
>>you are going for charge air cooling, propane isn't your choice.
>>
>>I DO get those temps. I can make up a graph from one of my logs if you like.
>>
>>> <cough> I really doubt it, LPG goes from compressed liquid
>>> to a gas - mthanol simply evaporates, the discussion is about
>>> direct LPG injection into the ports...
>>>
>>> rgds
>>>
>>> mike
>>>
>>> At 03:35 PM 18/11/2002 -0800, you wrote:
>>> >LPG gas cools very little. Methanol will be 10x better for charge air
>>> cooling. I
>>> >should know, I get intake temps lower than 20F on a 70F at 30psi of
boost.
>>
>>
>>
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