View Full Version : Tea Candle Alcohol Stove Efficiency
LostInSpace
02-25-2006, 00:10
I would appreciate getting comments about my results for an open-flame tea candle alcohol stove from anyone else that has made one. This version is simply an empty tea candle cup. HogOnIce, are these results reasonable? I’m just wondering what an acceptable performance benchmark is.
How efficient is mine with respect to fuel consumption?
How good/poor is the boil time?
Tea candle fuel cup – 0.6 oz.
Fuel – boat stove alcohol, ten years or more old
Pot – 1.25 liter aluminum
Water quantity – 0.5 liter
Starting water temperature – 59 deg. F
Ambient air temperature – 68 deg. F
No wind screen was used. The pot support is one half of an electronics mini-box, so the mini-box provides some very minimal chimney effect.
190 deg – 8 minutes
200 deg – 9 minutes
212 deg – 10 minutes
Fuel burnout – 10 minutes 45 seconds.
The alcohol left a residue, not just soot, on the bottom of the pot, so I expect that the quality of the fuel is not that good.
In broad terms what I see in your results seems to be reasonably in line with what I have seen but there are some differences in the details - as with many things all the parts of the system have an effect in alcohol stoves:
- I always use a windscreen as this is probably the one area where heat loss is the highest
- I use a sheet of foil under the stove as a "bottom reflector" - I think it helps a little but the main advantage is that it keeps the heat from scorching the surface I am coooking on
- under the foil bottom reflector I will often have a piece of closed cell foam to insulate the stove from the cold ground
- another area that one may optimize is the distance from the tea light candle tin to the pot - based on other peoples work this distance is one of the critical factors in getting good efficiency
- the pot support itself is probably another item that affects the efficiency but I have less of a feel as to the effect - what I use is a 3 high cylinder of 0.5 inch hardware cloth but I mainly use this for reasons other than efficiency (provides very stable pot support for a beer can pot)
- the lid to the pot is another critical item for efficiency - recently I switched from a foil lid to using a tight fitting _insulated_ lid - this approach while it did cost me an ounce seems to have produced a significant improvement in the efficiency of the system
- lastly take a close look at the amount of water you _really_ need to boil for your cooking - I have found that the "standard" of 2 cups (.47 l) is more than necessary for most everything I cook - note however I am talking about ziplock cooking in a cozy - very little water loss to the cooking process
wrt the residue left by the fuel you used I would suggest getting some better fuel - alcohol should burn cleanly in a good stove system - avoid isopropyl alcohol - denatured alcohol (eg. shellac thinner) should burn cleanly and is what I use most - "dry gas" such as Heet can also be used - just make sure you don't use Iso-Heet since that is is isopropyl alcohol
wrt the burn time - yep that is about right - a tea candle burner is not as fast as some of the other burners but I am in no hurry when cooking
jasonklass
02-25-2006, 15:18
How much fuel did you put in there? That will determine the effeciency. Also, try it with new alcohol or better yet, HEET. The results you got are good but they can only get better with newer fuel.
I tried a tea candle stove with wicking material. It did not bring 2 cups water to boil at 25F ambient, it just warmed the water up a bit. It might work in warmer temps. It is a nice simple solution if you can get it to work.
I tried a tea candle stove with wicking material. It did not bring 2 cups water to boil at 25F ambient, it just warmed the water up a bit. It might work in warmer temps. It is a nice simple solution if you can get it to work.
yep that happens - what I do when I don't get a boil at lower temps is to just wait until the burner goes out then add some more alcohol and relight - the thin metal in the tea light candle tin cools off very fast so its less of a danger to refill than some other heavier burners - my technique is to pick up the burner - if I can pick it up then it is cool enough to refill - typically the second fill is just a partial fill and there is alcohol left over after the water boils - since I no longer use any wick I can blow out the flame on the burner and pour the left over alcohol back into the bottle
note also that I don't try to boil a full 2 cups of water - 1.75 cups is more like what I boil so as to ziplock cook a liptons meal
So you just use the tea candle base with no wick? I will try that. Do you fill it with acohol? half way?
So you just use the tea candle base with no wick? I will try that. Do you fill it with acohol? half way?
yes - just an empty tea light candle tin
the first time I fill it all the way with alcohol and then if it needs more time I just fill it half way - that is usually more than enough
LostInSpace
02-27-2006, 16:28
HOI, thanks for the detailed reply.
I have not yet run tests with a windscreen, as I have been testing inside, but I can readily see the need for a windscreen. As you indicate, it will reduce heat loss, and I suspect even in the absence of any wind.
My pot support is an aluminum U-shaped channel. As such, the bottom of it serves as a reflector. Two opposite sides are closed, and the other two sides are open. It just happens to fit the size pot I am currently using for testing. I suspect that some heat is reflected and contained by the pot support. The heat discoloration on the closed sides indicates that those sides spread the flame out to the edges of the pot over the open sides, but not excessively so.
This pot support is extremely stable. It could probably hold a 20# pot because it is extruded aluminum. However, the support is unnecessarily heavy, and I will have to lighten it.
By chance, the height of the pot over the tea light candle is 7/8 inches. My observation of the flame spread seems to indicate that this is a good height for this particular combination of pot and pot support.
Although my pot lid seems to fit reasonably well, it has not been on tight during testing. The lid is cracked to enable the thermometer probe to go into the pot. I suspect, as you discovered, a tight fitting lid will cause an improvement in efficiency, perhaps because the contents becomes pressurized to some extent.
I agree that 2 cups of water is likely to be excessive. I selected that volume just for the purpose of a benchmark.
I’m wondering what effect, if any, the pot diameter has on the optimum height above the tea candle burner. The pot I am currently using is too large. It certainly can be shorter, and of lighter gauge aluminum. If I get a narrower pot, then the physical dimensions of the pot support will have to change.
One advantage is that the tea candle burner needs no priming. It produces the desired flame shape immediately.
LostInSpace
02-27-2006, 16:31
How much fuel did you put in there? That will determine the effeciency. Also, try it with new alcohol or better yet, HEET. The results you got are good but they can only get better with newer fuel.
The tea light candle holds 0.6 oz., and I fill it to the top.
I have three quarts of this old alcohol left to play with, so I might as well use it up with experimentation.
jasonklass
02-27-2006, 23:26
The tea light candle holds 0.6 oz., and I fill it to the top.
I have three quarts of this old alcohol left to play with, so I might as well use it up with experimentation.
I agree. Use up what you have. But don't rely on that to provide an accurate measurement of effeciency. I'd be curious to know what the stove can do with HEET...Hmmm....wait, I think I have some tea candles over here.
I made a side burner tea candle stove. Material is too soft to support anything. I also used a cap from a Sake bottle for a warmer. Not enough volume of alcohol to get a boil from any amount of fuel, but after your regular stove brings your food to a boil, you can place the Sake cap underneath for a nice, slow simmer. Of course, you need a pot support for this. I'd rather use a Supercat stove and the ti foil windscreen I bought at Backpacking Light.
I've decided to use Esbit tabs in favor of alcohol for my Georgia section hike next month. You don't get the flame spillage around the pot. They're more efficient per oz. of fuel carried, and can't spill. They do smell a bit, and leave a small amount of residue (easily removed with a handful of sand) on the bottom of the pot, but I like them a lot more than alcohol.
Lost In Space!!!!
You did a great job on your stove, keep up the good work!!!!!!
I've made a few tea candle stoves, cute little things they are!!!!!!
My recent one has a central flame that concentrates heat right where its needed most and increases fuel efficiency. No tests have been made yet.
this is a photo of it:
http://img.photobucket.com/albums/v228/obijiwa/tc5dualflame003.jpg
jasonklass
03-12-2006, 11:50
Fireboy-
What did you use for the bottom of the stove? It looks like you used the tea candle upside down and then added a bottom of aluminum or something. Is this right?
The one on the left is a side jet, low pressure, made with two tea candle tins, one on top of the other, just like a pop can stove.
The one on the far right is an open flame made with two tea candle tins same as above. it has a wick in the center that aids in start up and continued burn. Because of the wick it will light in cold weather, I have tested it this year at 9 degrees F.
The one in the center is made with only one bottom tin. It has a hole cut in the bottom and a tube inserted and JB welded to support it. Air comes up through the center to give oxygen to central vapors, thus forming central flame. Fiberglass wick fills the area around the central tube, totally absorbing all fuel making it more safe than if it were the other way...If it were to be knocked over somehow, flowing fuel would not spill out.
jasonklass
03-14-2006, 00:04
The one on the left is a side jet, low pressure, made with two tea candle tins, one on top of the other, just like a pop can stove.
The one on the far right is an open flame made with two tea candle tins same as above. it has a wick in the center that aids in start up and continued burn. Because of the wick it will light in cold weather, I have tested it this year at 9 degrees F.
The one in the center is made with only one bottom tin. It has a hole cut in the bottom and a tube inserted and JB welded to support it. Air comes up through the center to give oxygen to central vapors, thus forming central flame. Fiberglass wick fills the area around the central tube, totally absorbing all fuel making it more safe than if it were the other way...If it were to be knocked over somehow, flowing fuel would not spill out.
Ahh. So you just kind of force them to fit together? I suppose the metal is soft enough to do this. I'll give it a try. Thanks!
Still working on the right pot stand, last night I got a 17 min. burn out of a full TC5. It started to bubble in 5 min. Cooked a full package of instant refried beans. I refilled the stove to half full and lite it again to get a good boil. It burned 7 min. the second time. Ill be using this one for my solo section this year. CAUTION !!! Be sure you can pick up the stove befor refilling ! If you can hold it in your hand it is cool enough to fill.
Lost in space!!!!!
Here is some additional info on tea candle stoves:
http://hikinghq.net/forum/showthread.php?t=1559
RuffianPoet
03-18-2006, 15:11
I just made my tealight stove. I cut down a tomato paste can to about 1.5" and notched it at the bottom & top to use as a burner. I used the foil reflector on the bottom and also used a 3" high foil windscreen/reflector. I am using a Fosters beer can pot. Anyways, the problem I ran into is that a significant amount of condensation beads up on the bottom of the pot in the early stages of burning. I can bring 1.75 cups of 52deg water to a rolling boil before the fuel runs out (approx. 11 mins in my kitchen with the windows open). Anybody have this problem? Is it even something I should worry about? Thanks!
~~~ Anyways, the problem I ran into is that a significant amount of condensation beads up on the bottom of the pot in the early stages of burning. I can bring 1.75 cups of 52deg water to a rolling boil before the fuel runs out (approx. 11 mins in my kitchen with the windows open). Anybody have this problem? Is it even something I should worry about? Thanks!
RuffianPoet,
Water is a byproduct of the combustion of alcohol. In the early stages of burning, your pot is cool enough to allow water vapor to condense on the bottom of the pot. This is normal. As the pot heats up, the water vapor no longer condenses on the pot's metal surface.
jasonklass
03-19-2006, 10:56
I "made" one last night. I'm really impressed with the effeciency. I got a rolling boil in 9 min. and an overall burn time of just over 10 min. on 1/2 alcohol. I tried 91% rubbing alcohol too but didn't like the soot. I found that adding insulation slightly decreased the boil time but also created orange flames and decreased the overall burn time so I think I'll just use it empty. Funny how we spend so much time making these complicated designs when an empty tea candle tin turns out to be so effecient!
Learn to bake with the tc5's:banana
http://hikinghq.net/forum/showthread.php?p=12183#post12183
LostInSpace
03-21-2006, 23:55
Lost in space!!!!!
Here is some additional info on tea candle stoves:
http://hikinghq.net/forum/showthread.php?t=1559
Thanks. Always good to get more info.
LostInSpace
03-22-2006, 00:02
I have found that too much heat reflected/concentrated by a windscreen or pot holder decreases the efficiency by increasing the alcohol burn rate too much. This seems to allow insufficient time for heat transfer to the water, so the alcohol burns out too soon. Anyone else have a similar experience? Perhaps a lighter guage pot (e.g., beer can) would provide better heat exchange.
Forestescapes
03-22-2006, 08:55
I don't know...
If you are going to simply burn metho in an open tea candle tin...can that really be called a stove?
The fun and cut fingers of designing a can stove that actually turns the fuel into gas is surely worth the effort!
Life was not meant to be easy...
dc
it rather surprised me when trying to find a fuel efficient burner to use with a beer can pot that the tea candle tin turned out to be the best choice for me but...
Life is full of little surprises
http://img.photobucket.com/albums/v228/obijiwa/teacandlestove010.jpg
This little potstand worked good for me. 50% windscre50 % potstand:)
jasonklass
03-22-2006, 21:27
http://img.photobucket.com/albums/v228/obijiwa/teacandlestove010.jpg
This little potstand worked good for me. 50% windscre50 % potstand:)
That looks like a cool stand but how could it block any wind with all of those holes? BTW, care to shre where to get that material and what it's called?
I added an aluminum ring to the interior of the tea candle tin to increase it's strength. The photo shows it in it's raised position, it slides down into the tin and will be flush with it's rim. It will support 15 pounds easily. ( 1 gallon H2O):)
I posted a photo of a side burner tea candle stove up above I think.
Jasonklass : The stand is made from the interior of a oil filter. I'll post a link tomorrow that will shed some light on it's ability to serve as windblock.
http://img.photobucket.com/albums/v228/obijiwa/tc5oven.jpg
jasonklass
03-23-2006, 21:25
Thanks Fireboy. So, do you still use another windscreen with this?
Jasonklass: this tc5 is a new concept, 2 tins joined together, came up with the idea at the end of January of this year.
I have not used it outside to field test it. As with all alcohol stoves/burners it is recommended that a windscreen be used.
Here is a photo of the oil filter used to get the material for the potstand. It also shows the pot used to test the tc5 (tea candle 5 grams) The burner weighs 1 gram and the potstand is 4 grams. Combined they make up the lightest and smallest stove in the universe, to infinity and beyond:)
The hand sanitizer shown makes an exceptable jelled alcohol fuel.(smells good too!!!!)
http://img.photobucket.com/albums/v228/obijiwa/TinyTP013.jpg
I was just out at Walmart and seen a "super" tea candle. Looks like about
1-3/4" in diameter or so and about 3/4" high. Thin looking material just like the standard tea candle, just larger. For all you "stove explorers" out there, see what you can do with them. I would think though that it would wiegh almost as much as my V-8 stove.
If you decide to accept this mission your on your own, this post will self destruct in 30 days.
Mike