Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
What else works as a fuel?
Let's say I'm stranded out in a desert with a car because I'm out of fuel, but happen to have an unopened can of toluene or acetone. I'm assuming one
could just dump either of them into the automobile tank, with more or less serious problems?
Acetone is pretty comparable in values to gasoline/petrol (flammability limits, vapor pressure, evaporation rate), flash point is a bit higher though
(-20C), though this value won't matter in the warm desert. Its autoignition point is also a bit higher (404 C). Heat of combustion of acetone about
the same as ethanol (33% lower) than gas per weight basis. Toluene about the same as gas. More importantly, toluene and acetone have fairly high RON
and MON values (values in US20090227823, US4398920), knocking also won't be a problem then. Acetone is hygroscopic (like the primary alcohols), but in
a short use shouldn't present a problem to fuel injectors.
Plastic and rubber compatability is a concern. Acetone has different compatabilities than gasoline and hydrocarbons. In some cases it's worse, in
others it's better. For the chemical compatability (from here): Acetone had generally more severe effect than high aromatic gasoline on polymers and plastics. In particular, acetone had a severe effect
on Viton, whereas the same gasoline was excellent in rating, and toluene was 'fair'. Viton is used as material for O-rings. Acetone also had a severe
effect on polyurethane, as did toluene. Here acetone is again noted to act severe on polyurethane (swelling), toluene rated fair, and gasoline good. Polyurethane is another common O-ring
material, EtOH and MeOH also attack it strongly. There are only certain O-ring types acetone is very compatible with: Chemraz, Kalrez, Teflon, Butyl,
Ethylene-Propylene, Polysulfide (source). Toluene also has good compatability with fluoroelastomers, teflon. The type of fuel tank could also be important. With a metal fuel tank
nothing should happen, but in a plastic (HDPE) fuel tank, acetone could maybe cause some damage (moderate effect rating) versus minor effect rating
for toluene. So, so far acetone could easily damage some of the plastics and rubbers. Making toluene the more realistic fuel possibility there.
Anything I've missed here?
|
|
|
Fleaker
International Hazard
Posts: 1252
Registered: 19-6-2005
Member Is Offline
Mood: nucleophilic
|
|
I'd imagine toluene would be a better bet. BTX (benzene toluene xylene) is a common octane booster for racers who buy the play 93 octane and want to
"upgrade" the fuel for more horsepower.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
|
|
|
Panache
International Hazard
Posts: 1290
Registered: 18-10-2007
Member Is Offline
Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
|
|
i often use a few litres of toluene when i'm low or out of petrol, AFAIK around 10% of australia petrol is toluene anyway. The 84 toyota corolla
doesn't seem to mind it.
I find it amazing that acetone has a milder rating than toluene for HDPE tanks, this must be an error. Boiling toluene and xylene are about the only
solvents for the polyolefins, excluding exotics.
I thought viton also was hardier than that, i mean what's the point of upgrading to viton o-rings if they are still relatively crap for acetone? I had
a viton diaphragm pump once that handled acetone alright (around 8hrs before the diaphragm carked it)
btw that o-ring link is great
[Edited on 22-5-2010 by Panache]
|
|
|
psychokinetic
National Hazard
Posts: 558
Registered: 30-8-2009
Location: Nouveau Sheepelande.
Member Is Offline
Mood: Constantly missing equilibrium
|
|
I'm not sure your 84 Corolla counts as a comparison vehicle.
You could run an 80s Corolla on a banana skin and it's still take you home.
Though, on the subject of toluene - isn't the low flash point of toluene a problem for controlled combustion?
“If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found
the object of his search.
I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.”
-Tesla
|
|
|
Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
I think a hydrocarbon generally would be the safer bet. Though not all lone hydrocarbons have the same compatability as gas does. In blends and as
fuel additives in small concentrations, this seems to be less significant.
Xylenes have some of the highest RON and MON values out there after some alkenes. Namely, the m- and p- isomers. Commercial mixed isomer xylene has
mostly the m- isomer, with more equal o- and p- isomers. Flash point is around room temp. Xylene is good with Viton. Severe effect with polyurethane.
Moderate effect stated with HDPE.
The acetone and toluene (and xylene above) data on HDPE was from Camlab. Their scale is not so vague as others. But some other ratings I've seen for
HDPE for xylene and toluene are poor resistance to unsatisfactory. To be on the safe side, as long as the gas tank is not of plastic, these would be
the better possibilities. Most automobile fuel tanks are said to be made of steel or metal.
The flash point of toluene would be a problem under cold temperatures.
|
|
|
franklyn
International Hazard
Posts: 3026
Registered: 30-5-2006
Location: Da Big Apple
Member Is Offline
Mood: No Mood
|
|
Any given fuel mix will have to be metered on it's own
which may mean changing carburator jets as needed
and fooling with the spark advance or retarding it.
Not so easily done with modern computerized igniton.
Methanol for example is consumed at twice the volume
of ordinary gasoline. You can get most engines to start
but whether it will run under load or burn the valves
because it is too lean requires some considereation.
.
|
|
|
Formatik
National Hazard
Posts: 927
Registered: 25-3-2008
Member Is Offline
Mood: equilibrium
|
|
To combust ethanol:
C2H5OH + 3 O2 = 2 CO2 + 3 H2O
Mass for EtOH = 46.07. Then oxygen: 96.
Atmospheric air has 23.3% O2 by mass.
So, 96*100/23.3 yields:
412.02g air per mole ethanol gives a ratio of 8.94 : 1 ethanol. When rounded is the same as the 9:1 given in this link: http://www.journeytoforever.org/biofuel_library/ethanol_manu...
Gasoline is given as 15:1.
I've estimated for:
Xylene: 13.6:1.
Toluene: 13.42:1.
Acetone: 9.5:1 (almost about the same as ethanol, methanol is even lower than both).
2-Butanone: 10.5:1 (MEK attacks materials like acetone, Flash point: -3 to -9C, octane number: 96.7 to 98.5, has close to as much energy as gasoline).
Butanol has a ratio of 11-12:1. Butanol.com claims butanol can directly be run in a gasoline combustion engine without any modification. The same site
claims gasoline ratio varies from 12-15:1. If that's true then xylene and toluene could work without modification (Panache is saying he already uses
some toluene), provided they don't chew up any material (though US6187171 states 7-8C aromatic hydrocarbons like toluene and xylene in excessive high
content in gasoline compositions are known to be able to adversely affect fuel system members, gasoline is mostly like C5 to C12 alkanes and only
little aromatics to begin with). n-Butanol also has a high flash point of 35C, which can make it difficult to start an engine in the winter time.
US5938799 claims for optimum compromise of flash point versus saftey and ease of starting, a flash point of 40C to 43C is preferred for a fuel in the
gasoline internal combustion engine. So this must be the upper limit of when it becomes drastically more difficult to get a starting ignition.
The oxygen sensor can detect and adapt to changes in oxygen requirement. Most modern cars can adjust for small changes. E85 cars can adjust
automatically due to computer chips they have, this kind of car would probably be able to run the acetone.
So, in short, anything that does not corrode car parts or attack the plastics and rubbers, has an air-fuel ratio between 11 to 15:1, is fairly
volatile, has an acceptable octane rating, has similar energy content to gasoline, and has a low enough flash point, should work unmodified.
Attachment: US5938799.pdf (807kB)
This file has been downloaded 494 times
[Edited on 23-5-2010 by Formatik]
|
|
|
ScienceSquirrel
International Hazard
Posts: 1863
Registered: 18-6-2008
Location: Brittany
Member Is Offline
Mood: Dogs are pets but cats are little furry humans with four feet and self determination! 
|
|
The local rally boys run on a toluene based mixture for more oomph.
I do not know how much tweaking is required to get it to run smoothly.
Diesel vehicles will run quite happily on jet fuel, a pilot friend ran his car on jet fuel 'donated' by the airport where he worked for years and it
is commonly used in ancillary vehicles at airports particularly by the military.
|
|
|
Panache
International Hazard
Posts: 1290
Registered: 18-10-2007
Member Is Offline
Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
|
|
the local jet boating dudes here run toluene/methanol apparently, 70-30 i think, this always seemed strange to me, too yin and yang, big inboard
motors. Jet boating dudes make nascar dudes seem civilized, but i don't like stereotyping.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
