Fw: Holden Commodore, Aerodynamics. AND NOW: WATER INJECTION...

[Danny Barrett]

Firstly, H2O2 is ##**VERY CORROSIVE**##!!!!!!!!! I hope you kknow what
you're doing with it. You'll notice that the H2O2 you get from the hardware
store, etc is VERY DILUTE...

Secondly, on H2O injection... Vaporise it FIRST by running your water line
around the exhaust manifold. The water (from what I can tell) will still
turn back into droplets while being compressed (see my reply of just a few
minutes ago to another email), but, at least, it will already have enough
heat in it to reevaporate when the compression is low enough. Then, any
EXTRA heat it takes from the reaction should make it expand (it would
already be expanded to a certain extent before it is put into the engine.

Danny Barrett.




>Hi yall, it's good to be back.
>
>Actually I really wanted to ask if anyone had any info about
>injecting hydrogen peroxide, downstream of a turbo or SC. I'd like
>to think with the right strength (30%?) you could get some of the
>water-injection intercooling effect, but also some extra O2 from
>the H2O2 breaking down. Hopefully it would all break down before
>hitting the fuel, if not that'd probably be "bad", so it seems
>like it's best suited to a low-efficiency SC and would only be
>turned on above some temperature.
>
>(Don't worry, I wouldn't do this any more than I'd do nitromethane
>injection, I just wondered what people had to say about it.)
>
>But while I'm here I can't resist this tidbit:
>
>Wayne Strasser wrote:
>
>> By injecting more water, the
>> normally-wasted heat energy is utilized to induce a phase change in the
>> water from liquid to vapor, which obviously raises combustion chamber
>> pressures since water (at STP) expands by a factor of ~ 1400 when
>> evaporated.  Obviously, there is some optimum point here, since the
>> existence of water molecules in the chamber impedes radical electron
>> transfer processes and drops temperatures (hence the impact on
>> detonation).
>> not sure where that optimum is....comments from all?
>
>The problems are the high heat capacity of water and the high latent
>heat of vaporization. You only get some number of kJ from burning
>your cylinderfull of gas+air, and the water takes a great amount
>of that heat to heat up and evaporate. Yes, it expands tremendously
>when it does evaporate, and that's the only way you might come
>out ahead, because otherwise that heat of evaporation will kill
>you. It might help to have the water almost at boiling when you
>inject it, but even so, compare water to some other hypothetical
>fluid with a very low latent heat of vaporization. This other
>fluid will use up much less energy evaporating, leaving much more
>to heat & pressurize the just-evaporated gas.
>
>(As an aside, does anyone have the actual figures for latent heat
>of v. for water, the the heat capacity of air? I think the former
>was something like 500cal/g but I'm really not sure. I'd love to
>make some actual calculations of some of this stuff.)
>
>OTOH it's exactly this high latent heat of v. that makes water
>injection so great for intercooling.
>
>Probably the optimum is somewhere near the point at which the
>water is heated almost to evaporation just before entering the
>cylinder. You get maximum usable intercooling (without diluting
>your charge with a tremendous volume of water vapor), but during
>combustion the water *does* vaporize, giving you the phase
>transition, but for a minimum of required heat. Now if someone
>can manage the perfect droplet size profile to achieve this...
>
>(The above theoretical b.s. aside, yeah, it's a research project.)
>
>   Chris C.
>
>p.s. got a cone shaped hat on order just in case I flubbed this one.
>
>
>