[Diy_efi] WI, methanol, and corrosion

[Greg Hermann]

At 5:55 AM 1/24/03, Dave Dahlgren wrote:
>How long does this phase change take?

ALL depends on how thoroughly atomized the water is. Evaporation rate is a
function of surface area to weight or volume.

I expect I could apply your lack of time argument to the evaporation of the
fuel (particularly if running methanol) and likely prove that the engine
couldn't possibly run because the fuel doesn't have time to evaporate-- in
fact, this may be touching on why alky fueled engines need to be run so
much richer than stoich !! Likely also gets into some of the why of Honda
=46-1 engines that pre-heated (mostly toluol) fuel.

If there is heat available, and lots of surface area, and the surrounding
gas is not saturated with respect to the vapor of the liquid which is
evaporating  (at the ambient temp), then evaporation is a FAST process.

Greg

you only have 18.46 milliseconds per cycle
>in this example.. The diesel tractor puller with 100 lbs of boost have a ch=
arge
>air temp or at least around 650 to 700 degrees.. I can see where water inje=
ctor
>would make a huge difference there. Also they are going slow relatively
>speaking
>so a air to air inter cooler would be less efficient as well and a water to=
 air
>would be very large as well as the water tank. The construction of an inter
>cooler for 100 psi would be very large and very heavy as well so comparing=
 to a
>tractor engine I think is missing the mark. I think that the WI has combust=
ion
>benefits but find it hard to believe you can process the water fast enough =
in
>the intake runner to change the air temp by 140 deg F in 18.46 msec to get =
you
>to the point a normal IC would be..
>Dave
>
>Greg Hermann wrote:
>>
>> At 3:43 PM 1/23/03, William Shurvinton wrote:
>> >Have a look at http://not2fast.wryday.com/turbo/glossary/turbo_calc.shtm=
l
>> >
>> >About 450cc/min to get it back to ambient
>>
>> You're NOT going to get it back to ambient with water. Would be WAY past
>> saturation.
>>
>> (and that's without fuel
>> >cooling).200cc will give you about the same as your IC.
>>
>> About 1 lb (about 400 cc) or so to get it into the 120--125=B0F range.
>>
>> This puts you in the range of 1 psi of water vapor pressure--
>>
>> (NOTE: steam tables NOT checked on this)
>>
>> (Assuming you are talking 270 degrees _F_)
>>
>> Compares to you needing 2.3--2.5 lbs/min of fuel for this air flow.
>>
>> Greg
>> >
>> >Yes that's a lot, but water is cheap and on the street or strip you don'=
t
>> >run 20PSI for very long. For the daytona 24 it might not be such a good
>> >idea.
>> >
>> >Certainly doable and worth considering, depending on your application
>> >
>> >Bill
>> >----- Original Message -----
>> >From: "Dave Dahlgren" <ddahlgren at snet.net>
>> >To: "List for general do-it-yourself EFI talk" <diy_efi at diy-efi.org>
>> >Sent: Thursday, January 23, 2003 9:11 PM
>> >Subject: Re: [Diy_efi] WI, methanol, and corrosion
>> >
>> >
>> >> so just how much water to you need to cool 30 lb/min of air at 270 deg=
rees
>> >down
>> >> to something reasonable?? that is approximately a 2 liter with 20 lbs =
of
>> >boost
>> >> and no inter cooler at 6500. A head start is a typical inter cooler wi=
ll
>> >bring
>> >> it down to 130.. Seems like a lot of BTU's to me.
>> >> Dave
>> >> Adam Wade wrote:
>> >
>> >
>> >
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