Alcohol vs Shellite vs Gas stoves

[Tony]

This is the results of some test that I did to compare Alcohol, Petrol (White gas or Shellite) and Gas (Canister) stoves.

I tested a Trangia 27-1, a MSR Whistperlite and MSR Pocket Rocket all of them are considered to be classic stoves and are available in most countries of the world.

I tested them through a range of adjustment settings from the fastest to the slowest that I could get the stoves to operate with in reason. I used a 1l Snowpeak Titanium pot 150 mm diameter with a specially made Stainless Steel lid with a hole in the middle so I could place my temperature measurement probe into the water.

In all test I raised 1liter of water 80C, the ambient temperature was about 20C.

Adjustment

With the Trangia I used the simmering ring to choke the flame down to produce the slower heating rates, the fastest heating rate used was with no simmer ring.

The Whisperlite was the hardest to adjust, I did this by pumping different number of pumps into the fuel tank from a few pumps at a time to about 40 pumps and the valve was opened fully in all tests.

With the Pocket Rocket, this was simple I adjusted the heating rate by adjusting the valve from very fast to very slow, if the valve was opened too much lift off of the flame was experienced



Results

The results show the amount of fuel used in each test in grams vs time.

Trangia

Note that no matter how slow I adjusted the heating rate it used the same amount of fuel from 12 minutes to 30 minutes. 23-24 grams, Note the Trangia used nearly twice as much fuel as the correctly adjusted Pocket Rocket.

Whisperlite

The Whisperlite showed great improvement in efficiency 25% with slowing down the heating rate, this stove is not design to simmer and is very inefficient at the normal setting, though it has the advantage of working in very cold conditions.

Pocket Rocket

The Pocket Rocket also benefited from slowing down the heating rate a 25% improvement was seen. Note as can be seen from the curve (yellow line) that using the Pocket Rocket at too high a heating rate is a waste of energy, a time of around 12 minutes seems to be the optimum and heating rate faster was a waste of fuel and slower was a waste of time. Please note the most efficient fuel/time point 12 minutes coincides with the fastest heating rate from the Trangia 12 minutes, I am not sure if this means anything though but I found it an interesting point. Upright canister stoves have problems working in cold conditions but they can still work in the cold if used correctly

I hope this information is of some help to stove users and prospective stove buyers.

Tony

[tas-man]

Tony, is my reading of your results plot that shellite stoves are more efficient run full throttle than in simmer mode as compared to the others? IE the conversion of fuel to heat in the pot so to speak, works best when quickly boiling a billy? It would be interesting to do a similar chart with the total weight of the stove/fuel/canister combination related to heating capacity to give some indication of the heating output per Kg of equipment that could be compared to work out for longer trips what might be the most weight efficient cooking combination to carry.

Can you increase the size of the image so the info can be more easily read?

[whiskeylover]

I have just looked up a site comparing fuels Have got it listed below . Approximate energy levels in different fuels
White gas: 10630 kcal/kg, 44,5 Mj/kg
Kerosene: 10270 kcal/kg, 42,9 Mj/kg
Diesel: 10290 kcal/kg, 43,1 Mj/kg
Aviation fuel: 10220 kcal/kg, 42,8Mj/kg
LP-gas: 11900 kcal/kg, 49,8 Mj/kg
Spirits: 7130 kcal/kg, 29,9Mj/kg

As you can see spirits or metho produce the least ammount of fuel for weight and lp gas is as half as good again .I seem to remember from my apprenticeship cookery days that if you have a burner on really high, a lot of heat just goes straight up past the pot and heats the air, and is just waisted.I think thatis why the jetboils are more efficient .The metho burner would not produce a lot of excees heat and waste it compared to the other two burners.But as the chart shows it takes nearly twice the ammount of weight in metho to boil the same ammount of water as gas does.thanks Tony gets the Brain thinking ,I must admit before converting to using a shellite /multifuel burner on my trangia I loved the metho burner ,simple nothing to break no jet engines to listen to and by the time the tent was set up ,mats inflated and sleeping bags set up the kettle was boiled ,and a cup of coffee could be had.

[Tony]

Hi Tas_man,

Tony, is my reading of your results plot that shellite stoves are more efficient run full throttle than in simmer mode as compared to the others? IE the conversion of fuel to heat in the pot so to speak, works best when quickly boiling a billy?

Absolutely not, I do not get the same results from the graph, I would like to thank whiskeylover for posting the heating values of fuel I should have done it in the previous posts, I would like to correct the value of Spirits, the value posted of 29.9 Mj/kg is for IPA which is not a suitable alcohol fuel for stove use, Australian Methylated spirits has a heating value of closer to 26 Mj/kg which is approximately half that of butane/propane fuels (I would also like to add that Australian Methylated Spirits 95% ethanol is about the best Denatured alcohol fuel available in the world)

As whiskeylover correctly pointed out it is why the Trangia uses twice the fuel that the Pocket Rocket used.

Back to the Whisperlite as Shellite has nearly the same heating energy as butane/propane from the graph it can be taken from the graph that the whisperlite is a very poor performer at full throttle and that slowing down the heating rate improves its efficiency dramatically. There are several reasons for this and again whiskeylover alluded to this, one reason is that the whisperlite at full throttle blows most of its heat up the sides of the pot.


Tony