On 8/25/13 11:23 AM, Peter Terren wrote:
Ethanol doesn't work.
Tried it a week ago by chance.
Methanol is harder to get and is toxic.
Back when I worked for the effects shop, I spent a lot of time trying to
come up with various colored flame mixes for use in a variety of atomizing
burners.
Methanol is, I've found, the best for colored flames, but you need to have
a bit of water in the mix (because the ionic salts you're interested in
are not soluble in alcohol, but are in water)
Ethanol is hard to get work as is isopropyl. I think the problem with
isopropyl, which seems to have visible flames without a salt, is that it
has too little oxygen so it burns incompletely, and you see the
incandescent carbon.
It might also be a stoichiometry thing and how the air/fuel mixture works.
Methanol has a lot more oxygen in the molecule compared to the carbon.
Hence the risk of perfectly colorless methanol flames in race cars.
You might also try mixing a small amount of nitromethane, for the oxygen
content. The problem there is that nitromethane is unstable, expensive,
and stinks when it burns. Maybe propylene oxide (even more unstable,
though)? What ever works in drag racing fuel (as opposed to gas),
basically.
Once source for methanol and methanol with small amounts of NM added, is
the hobby store, since it's used in glowplug/2 stroke engines. You'd want
the mix without the castor oil, of course.
Your local chemical supplier can probably get you gallons of methanol,
although that's sort of a weird amount. Labs use liters of fairly high
purity stuff; Commercial and racing applications use it by the 55 gallon
drum or larger. If you call a racing fuel distributor you can probably
get it in gallons. VP Fuels in the US and Australia.. although in
Adelaide, I see that Scotcher Race Fuels is a distributor.
There might also be an application for using a straight water mist, since
what you really want to do is get the ions into the flames, and the more
"stuff" that has to evaporate the more the flame cools, and then can't
ionize the metal. I was working on a scheme using a methane flame and
water mist, but it turns out that getting pure methane is actually a lot
harder than getting methanol. Regular old natural gas has significant
ethane and propane, as well as other stuff, so it's hard to get a
colorless flame.
Your best bet in the long run might be a propane burner (like a stove) to
make hot air, then inject your methanol/water/metal salt solution into the
exhaust stream.
(and that's sort of what the KREC does, no?)
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