[pct-l] RE: Fuels and Stoves

[ROYROBIN@aol.com (ROYROBIN@aol.com)]

Bill Murdoch on the BackpackingLight list has raised some interesting 
questions about alcohol stoves, alternate fuels, etc., and has quoted some 
useful information (not verified by me) about melting points, flash points, 
boiling points and heat content.  (See his original message below.)

The bad news is that I've totalled one CatStove testing some of these ideas.  
Here are the results:

Kerosene does not work in a CatStove.  Same for Lamp Fuel.  Same for Coleman 
Fuel.  There seems to be very little difference between these fuels, as used 
in an alcohol stove.  They all burn very hot, are oxygen starved and tend to 
set the surrounding area on fire (probably in search of air.)  Because they 
are oxygen-deprived, they create a lot of smoke and soot.  This reinforces my 
suggestion that using gas fuels in an alcohol stove is dangerous.  It is also 
dirty, messy, and almost impossible to clean up.  

There is some very good news!  I've never thought much of using a simmer ring 
on the CatStove to make it burn slower.  It works, but is a nuisance to fool 
with.  Here is the BEST way to make a CatStove simmer, and you can leave the 
simmer ring at home:

Bring your meal to a boil using two tablespoons of alcohol, as usual.  That's 
enough fuel to bring a pint (500 ml) of water to a rolling boil.  Before the 
alcohol burns out, drop some paraffin (about 1/2 the size of one Esbit 
tablet) into the stove.  It will melt and be absorbed into the fiberglass 
wicking, where it will burn long after the alcohol has all been used up.  A 
bit of candle will do the job just as well.  (For those who speak English 
instead of 'Merican, I'm talking paraffin WAX, not kerosene.)  A chunk of 
paraffin about the size of a quarter should simmer your pot for 8-10 minutes 
after the alcohol burns out.  It does create some smoke and soot, so 
experiment to find the amount that suits your needs.  Use too little rather 
than too much.

Roy Robinson
   

---------------------------

Original Message:

From:  WSMurdoch@a... 
Date:  Fri Dec 28, 2001  6:45 am
Subject:  Fuels and Stoves


Some time ago we had a little discussion about stoves and stove fuels that 
was joined by Corry from MSR. The general run of the thread was that alcohol 
stoves were light, but their fuel was heavy; that gasoline stoves were heavy 
(especially if you include all the pieces), but their fuel was light; and 
that propane/butane/isobutene stoves just might combine a light stove with 
light fuel, but a gaseous fuel has its problems with availability, container 
weight, and cold weather use.

Anyway, it got me looking at fuels. I made up this table. (It is a table in 
Word 10 pt courier new. Who knows about web browsers.) It lists some fuels, 
their chemical formulas, melting points, flash points, boiling points, and 
heats of combustion. I picked carbon and coal because they are sort of like 
charcoal; propane, butane, and isobutene because they are camping gases; 
hexane and octane because they are major components of gasoline and Coleman 
fuel; decane because it is like kerosene, and pentacosane because it is like 
paraffin wax. Toluene and xylene are both sold as paint thinners or 
solvents. Methanol, ethanol, and isopropanol are the alcohol fuels. 
Diethylene glycol is the stuff in the chaffing dish lamps at Sams Club. 
Trioxane and hexamethylenetetramine are the camping solid fuels. The rest, 
from gasoline to stearic acid, are other fuels.

Material m.p. f.p. b.p. Hc _

(°F) (°F) (°F) (BTU/lb)
Carbon C 14,096
Coal 14,310
Propane C3H8 -306 -104 -44 19,944
Isobutane C4H10 -255 -74 11 19,629
Butane C4H10 -214 31 19,679
Hexane C6H14 -140 -7 156 19,130
Octane C8H18 -70 55 259 19,029
Decane C10H22 -21 115 345 19,031
Pentacosane C25H52 128 395 755 18,773
Xylene (1,3) C8H10 -54 77 282 17,760
Toluene C7H8 -139 39 231 17,601
Methanol CH4O -144 52 148 8,570
Ethanol (100%) C2H6O -173 55 173 11,531
Isopropanol (100%) C3H8O -126 53 180 13,100
Isopropanol (70%) 71 8,854
Diethylene Glycol C4H10O3 13 255 473 8,736
Trioxane C3H6O3 143 113 238 6,609
Hexamethylenetetramine C6H12N4 536 482 538(d) 12,079
Gasoline -49 77-437 18,900
Kerosene 115 320-572 18,510
Diesel Oil (2D) >125 348-698 18,250
Coleman Fuel <0 >100
Mineral Spirits 104 
Charcoal Lighter Fluid 120 >148
Lamp Oil 120 370-520
Paraffin Wax 133 399 18,074
Stearic Acid C18H36O2 157 385 707 15,900


Looking at the table, it appears that fuels with combined oxygen are low in 
heat content; the alcohols, diethylene glycol, trioxane, and stearic acid 
have lower heats of combustion than the hydrocarbon fuels. A smaller heat of 
combustion benefit comes from having a larger proportion of hydrogen and a 
lesser proportion of carbon in the fuel; from propane down to toluene the 
heats of combustion decrease as the ratio of hydrogen to carbon falls from 
2.7 to 0.9 and coal and carbon with little and no hydrogen have still lower 
heats of combustion.

The data match experience. Alcohol stoves need about twice the weight of 
fuel as either gas or gasoline stoves to boil similar amounts of water. 
Ethanol is a better stove alcohol than methanol or 70% isopropanol. Coleman 
fuel is a little safer as a fuel than gasoline. Trioxane is easier to light 
than hexamethylenetetramine (lower flash point), but it gives off less heat. 
Butane stoves do not work well in cold weather.

Now two questions.

Has anybody played with paraffin wax as a fuel? I know there is a Nu-Wax 
candle stove and that is oh-so-slow. I also know that the guys who fly dry 
cleaner bag balloons use 10 or more birthday candles to lift the balloons. 
And, I have boiled a pint of water in 7 minutes over 0.5 oz or 12 birthday 
candles, but is smokes up the pot a lot. Candles would let you have a fuel 
with no stove and candles cannot spill. Is this a better way?

What happens if you fuel an alcohol stove with hexane, Coleman fuel, or 
mineral spirits? I know the top of my Trangia stove says not to do it, and 
several of the alcohol stove web sites have warnings, but what happens? 
Would a different hole drilling arrangement in a Photon stove let it burn a 
higher heat content fuel? Can you burn kerosene or lamp oil in a cat stove? 
Would that give you the combination of a light stove with a light fuel?

Bill Murdoch