[pct-l] Let Mags BURN E85 IN ALCOHOL STOVE

[Jim Eagleton]

I'm having a little trouble mixing humor and my geeky analysis.  

a)  Why on the internet do people with the least knowledge want us to know just how smart they are?  (not just Tobin) While I am not impressed by your analysis, I do like your safety values.  Everyone, keep safe.  

 

b)  Ethanol (denatured alcohol) and especially methanol (yellow HEET) are MORE volitile than octane (gasoline).  If this was not true, you could leave the cap off your E85 bottle until the octane escaped and you had an even closer approximation to ethanol.  

 

c)  I would think that E85 would work... until it doesn't work.  My guess is that the problems listed below, will limit the use of E85.  However, E85 always has an advantage on cost, energy/weight, and less likely to be out of stock (not sure about overall availability, it was very poor in 1976).  Wouldn't it be cool if E85 worked for 85+ % of the burn?  

 

d)  While the E85 may start off very similar to ethanol, at the end of the burn, it will approch octane.  Even a minute of soot will make your pots pretty dirty.  You might try using a small excess of E85, and taking the pot off the stove well before the end of the burn.  If you only wasted the last 5 % of fuel, you would loose any weight savings for the E85 blend.  Octane burns yellow because not enough oxygen is mixed in.  As a first approximation, the ideal gas law says that a given volume of gas (at a given temperature and elevation) will have the same moles of gas.  A mole of octane takes 4.2 times more air to burn than a mole of ethanol.  Octane takes 8.3 times more air to burn than a mole of methanol.  So I would try E85 in a stove with small holes (small volume) like a pepsi can stove and not large holes like a cat can stove made from a paper punce.  

 

e)  Not sure how big a problem flare-ups would be at the end of the burn.  It is not just that octane has more heat than alcohol, and the stoves are tuned to the wrong fuel, but also, octane has a lower heat of vaporization so it will be more unstable.  I think the overriding factor is the stove design, so we get to f...  Mags can you find a  stove with holes smaller than this?  

http://www.pmags.com/joomla/index.php/Backpacking-and-Hiking-documents/mags_gear_cc.html  

 

f)  Remember Graves Law:  Always light E85 with your left hand and your good eye closed.  Actually, Dr. Graves said "always check for steam leaks with your non-dominent hand".  She must have thought that someday we would have a left handed president.

 

g)  It seems to me E85 is not an ideal fuel.  If you have to tune your stove to E85, do you carry 2 stoves?  What about the smell and contamination on you hands when you fill your bottle and the stove.  What about the small quantity of tri-methyl death in commercial gasoline?  

 

Regards, 

toc  

Jim

 


 
> From: tobin.van.pelt at mac.com
> To: pct-l at backcountry.net
> Date: Fri, 17 Apr 2009 07:33:58 -0700
> Subject: Re: [pct-l] DON'T BURN E85 IN ALCOHOL STOVE
> 
> I want to shout out here as well.
> 
> To Robert Reiss, I TOTALLY AGREE with Numael (see below):
> 
> I am not a chemist ... but do indeed have an extensive rocket science 
> background.
> 
> Any type of motor fuel, even E/85 with only 15% gasoline is a bad idea:
> 
> a. not likely to burn properly with a light weight stove - fuel to air 
> ratios will be all wrong
> 
> b. are very volatile fuels - you'll be carrying a bomb on your back! 
> Big difference between a vapor burning such as alcohol and a vapor 
> exploding such as gasoline. E85 won't be that explosive by itself ... 
> BUT the gasoline vapors could come out of the fuel much faster and 
> accumulate somewhere (like in your pack) ... and then it is not 15% 
> anymore ... bad situation. Marine explosions happen in this 
> manner ... gasoline boats sometimes explode ... this is why most boats 
> use diesel. Diesel vapors are not flammable unless they are under 
> pressure.
> 
> c. worse are the flame stability issues - if you did get one to light 
> with a tuna can stove and burn ... it could burn stable for a few 
> seconds (making you think it was safe and stable), then build up a 
> rich gasoline fuel pocket in the flow pattern and then explode later 
> with no notice. Like a chugging effect. It could exhibit very 
> UNSTABLE thermal/aero dynamic burn patterns.
> 
> d. there is no real cost tradeoff argument here - even if you did get 
> E85 to burn stable ... it would do so less efficiently for purposes of 
> heating food (more volatile, faster burn initially, less time for heat 
> transfer, etc) - so your factor of $14/gal savings ... could be closer 
> to $8/gal or less. You will go through 12 gallons on a thru hike. 
> We're in the $100 saving region. Not worth it! Plastic surgery and 
> fines for burning down national forests are too high.
> 
> e. there is a culture of expert alcohol stove builders that has 
> emerged. I have studied these guys designs. Built a few myself. 
> They are GREAT trial and error inventors. If E85 worked in anything 
> close to existing tuna can style configurations - TRUST ME ... they 
> would have discovered it by now! SuperCat inventor Jim Wood at http://www.jwbasecamp.com/Articles/SuperCat/index.html 
> says this:
> 
> "I've not personally tried E85 in a Super Cat stove, but I've heard 
> from those who have. They've reported that although the fuel contains 
> only about 15% gasoline, it burns with substantially the same 
> properties as regular gasoline. The resultant low-temperature, sooty 
> flame apparently burns mostly yellow and fails to pressurize in the 
> stove, making E85 largely unsuitable for use in a Super Cat."
> 
> (This rather benign warning was conducted in a laboratory setting in a 
> garage somewhere - and doesn't event touch on safety considerations. 
> It does point out that people have tries it and it does not work.)
> 
> In summary - rethink this PLEASE and BE CAREFUL. With all of that 
> being said ... it would be fun to do VERY CONTROLLED experiment with 
> the right equipment to find out what happens ... could be a great 
> "funniest home video" clip :-)
> 
> See you on the trail.
> 
> Tobin
> PCT -09
> 
> 
> On Apr 16, 2009, at 10:13 PM, pct-l-request at backcountry.net wrote:
> 
> > Greetings,
> >
> > I am the father of a PCT hiker (and have hiked portions of the PCT 
> > myself),
> > but have posted here very seldom, so please forgive the intrusion. 
> > I want
> > to speak against using fuels that are not intended for a particular 
> > stove or
> > cooking mechanism, in particular against using motor fuel as a 
> > substitute
> > for another fuel (unless the stove manufacturer recommends it 
> > explicitly).
> >
> > Motor fuel is a totally different animal: its vapors are explosive, 
> > it burns
> > much hotter, and it's much harder to extinguish. A friend had an 
> > accidental
> > ignition of motor fuel in a can, which unfortunately splashed on his 
> > leg as
> > he tried to put it out. From this accident he has had several 
> > operations,
> > therapy, skin transplants adding up to hundreds of thousands of 
> > dollars, and
> > he will never be the same.
> >
> > Please stay safe on the trail, and have a wonderful journey!
> > Numael
> 
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