EFI fuel pump and water.

[Chris Conlon]

At 11:42 PM 7/18/00 -0400, Joseph Obernberger wrote:

>> The reason I found that page was that I was specifically thinking
>> of using ultrasonic evap for water injection. I wanted the
>> ability to finely modulate water flow, also the physical layout
>> worked very well in my intended app. Particle size can be super
>> small... maybe too small for WI use.
>>
>
>    Wouldn't you need to have a system that had some amount of
>pressure to it to inject into the engine (post intercooler)?  It has
>to be at least a little over boost - right?

Yes and no. Normally yes, but in this case the WI would be in
the plenum.

Take your basic inline 4. Mount a supercharger next to it, with
the outlet of the SC facing towards the intake ports, except that
the SC outlet is near the bottom of the block. The "bracket"
holding the SC to the block is basically a big rectangular box,
on the outside, which is also the intake manifold.  The bottom
part is the SC outlet, oil coolers (running water) mounted flat
serve for intercooling, and the top section divides into runners
per port. The corners inside are mostly smoothed via sheet metal
and Devcon Al epoxy putty.

The original idea was to have a water spraybar, inside the plenum,
at the top, spraying down onto the IC core. This would help pick
out the smaller droplets, bigger ones would be a bit more likely
to fall through to the plenum floor. So there needs to be a 
pickup system... well it turns out the ultrasonic evap transducers
really want to be submerged, due to heat dissipation issues. So
now I'm thinking ditch the spraybar, and just set up a mini pump
to keep 1" of water in the plenum. (The SC outlet is comfortably
above this level, the plenum is maybe 12" high.) The mist from
these evaporators is very very fine, about the finest you can make
with any method at all, (or at least it can be) so the mist is
just carried away in the airflow.

The idea died because evaps capable of 550-1100cc/min (25%-50% of
max fuel flow) are expensive, suck a fair bit of power, and would
be somewhat cramped in that space. Using smaller units just to
catch and re-atomize overly-large water drops from the spraybar
probably would work... but I don't see an advantage of that over
just the spraybar system.

Anyway... that was the idea. If anyone wants to make it work,
good luck, but the issues of power vs. flow, and size/cost of
transducers were pretty cut and dried.

   Chris C.

----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org