Forum Index » GEAR » Most fuel-efficient on Snow Peak Litemax (or other canister stoves)

 Display Avatars Sort By: Date (Chronological) Date (Reverse Chronological)
 Misha Berger (aeropenguin) - F - M Locale: Berkeley, CA Most fuel-efficient setting on Snow Peak Litemax (or other canister stoves) on 08/06/2012 19:21:51 MDT Thanks to REI's online "compare" feature, I now have both the lightest stove and most fuel-efficient canister stove commonly available.But what setting do I use to maximize this efficiency??? I seem to remember someone mentioning medium flame being best. Has anyone done any analyses on this?Of course the temperature, pressure, and pot dimensions/material will all have an effect on this, so it may just be best to perform the test myself when I get up to altitude. However, since I won't be bringing a weigh scale with me or crossing a post office until a ways into my trip, even a general guideline would be helpful for now.The test is really easy to perform -- just divide the change in degrees of the water by the change in mass of the canister for a given volume of water and voila. (The full expression would be Q/m_fuel=m_water*c(T2-T1)/m_fuel, where m_water is the volume in mL and c=1 cal/mL/*C and Q is energy in calories.)I suppose I could make a makeshift balance beam on location but this would be more tedious and less scientific than I'd like. Edited by aeropenguin on 08/06/2012 19:54:23 MDT.
 Franco Darioli (Franco) - M Locale: Melbourne Most fuel-efficient on Snow Peak Litemax on 08/06/2012 19:40:32 MDT I have the Kovea branded version of that stove.When I used that , a few years ago, I did perform some tests and concluded that it was most efficient ,for a boil, at around half throttle.That was using Ti pots around around the 900ml/ 1 liter size, about 5" wide.my take is that with a bigger flame a lot of the heat was just going up the side therefore almost wasted.In practice I try to keep the flame of my gas stoves at around 1/3rd less than the pot diameter.But yes that is not very scientific, it just happens to work for me.Franco
 James Marco (jamesdmarco) - MLife Locale: Finger Lakes Re: Most fuel-efficient setting on Snow Peak Litemax (or other canister stoves) on 08/06/2012 20:39:48 MDT Misha,Yeah, Basically you are doing what I tried 20 years ago. You bump into all sorts of variables. Wind, air temp, thickness of pots, distribution of heat, etc...To call all this stuff meaningless is not worthy of my scientific training, but basically, ignoring heat loss and assuming a good wind screen/heat trap, you'll find that the lowest heat you can still manage to burn consistently on a stove, the more efficient it is. Nearly linear between 3 and 14 minutes, anyway. In a lab, boiling to 200F on a digital thermometer, I get good efficiency at about 13-15 minutes for two cups (16oz) of water using a small alcohol based stove: roughly 1/3oz of 50/50 ethanol/methanol from 40F, to 200F. (Note that 200F was chosen to avoid the effects of altitude and day to day air pressure changes.) Efficiency goes down about .05oz per minute for each minute I boil faster. The best time vs fuel was about 5:30 and 5/8oz of alcohol. An even slower boil runs into things like radiative cooling and convectional loss over the lid. So it starts leveling out...bumping in to that "too slow" region that makes no sense out camping. Since no canister burns that slowly, I can only conclude that the lowest possble flame on a canister stove (or WG or Kerosene stove) will be the most efficient. Indeed I tried it with two canisters I had (picked up at the same time and from the same place) and I got 5-6 extra boils out of the canister on "as low as it would go" as opposed to the canister on 3/4 throttle. This wasn't very scientific, though. I just kept cycling between emptying the pan and pouring a premeasured amount in as it alarmed, filling the premeasure, again. Took a couple hours. A heat exchanger on the bottom of the pot will help as much as 15%. I think this pot is one that will work on any stove: Olicamp XTS Pot (1L size) A side screen will add another 5-8%, minimum. I think the adds say 40%, well...maybe for a half or quarter cup at a time.
 Misha Berger (aeropenguin) - F - M Locale: Berkeley, CA Re: Re: Most fuel-efficient setting on Snow Peak Litemax (or other canister stoves) on 08/07/2012 00:03:08 MDT Fascinating! I will definitely test this for myself when I get the chance. This outcome strikes me as quite elegant, as it is largely independent of (mild) temperature and pressure variation because as you said you can't turn the flame down low enough for the heat loss from the top and sides to outweigh the benefits of the low flame anyway.Do you think the reason for this trend is simply the efficiency of the burn, or just the flames whisking around the edges of the pot? In other words, should I be worried about greater exposure to CO while waiting for my water to boil on low heat? We did assume no wind ;)It would be interesting to repeat the test with a catering tray for a pot, which would be similarly thin, and the bottom would approximate an infinite plane and therefore eliminate fringe effects. Edited by aeropenguin on 08/07/2012 00:07:29 MDT.
 David Thomas (DavidinKenai) - M Locale: North Woods. Far North. Re: Most fuel-efficient setting on Snow Peak Litemax (or other canister stoves) on 08/07/2012 01:04:35 MDT Misha: I'm a UCB BS ChemE living 2100 miles to your NW.Short version for a cannister stove:Paint the bottom of your pot. Surprisingly, white, black and red paint are all black in the infrared (as determined side-by-side on identical stoves in my well-equipped garage).Wider pots are more efficient than tall pots.Moderate flame setting. I want to say a little higher in cold weather, a little lower in warm temps, but I haven't confirmed it experimentally.A good cover cuts evaporative losses.A modern HX pot comes out ahead after 5-10 liters of boiled water. i.e. not needed for a weekend trip, but desireable beyond that. Definitely for any snow camping where you are melting snow for drinking water.A modern HX pot also can extract enough heat to allow an insulating "coozy" around the sides of the pot which obvious reduces heat losses, but I'd only do that if I was simmering for a long time*Most all the resistance to heat exchange is in the air film on the outside of the pot. Vortex generators akin to those on airplane wings help at almost no weight (checked that myself)Windscreens help all the time. A huge amount in the huge.*This is a bigger tip than all the heat exchange mumbo jumbo: Don't think of COOKING your food (time and temperature), think of it as REHYDRATING it. Soaking in cold water cuts cooking time of noodles, ramen, beans, rice. Letting stand once boiled allows you to stop the burner much sooner. (You really don't want to eat 100C food anyway!). Experiment at home, but most foods can be perfectly cooked only by bringing close to a boil once (at most, one more time 5-10 minutes later). Never simmering (by selecting WHAT you cook and changing HOW you cook it) saves a LOT of fuel.