4 1/2oz Kelly Kettle

[Rog Tallbloke]

Interesting pics. My stove is made from tealight cups too. It burns 12g in around 7-9mins depending on how hot it gets.

My latest design is up to 56% thermal efficiency and boils 16oz of 12C tapwater in 7 mins with 11g of fuel. The unit is down to a thrifty 63g including insulation and stove.

[Dan Yeruski]

My tealites are not open burners. They contain fiberglass and release the fuel at a controlled rate and the opening is 1/2 the original size of the tealite.

Your improvements are impressive.

How many grams does 15ml of alcohol weigh? I'll be using weight for an upcoming stove test for a mini kerosene stove that I've designed.

Here are some quotes from my website http://www.bplite.com

by zelph on Tue Feb 26, 2008 2:02 pm

I did a kitchen test yesterday using 13ml of denatured. Water boiled at 20 min. and continued to boil for an additional 3 min. until flame out. Will do a test without central tube heat exchangers today.

by zelph on Tue Feb 26, 2008 9:16 pm

Did the test without the tubes in the chimney.

13ml of denatured, 2cups of 70 degree water to start.

Flame out at 21 min. Water temperature rose to only 150 degrees

What a difference the tubes made. Terrific heat exchangers for what its worth.

I think it's an interesting concept, I may take it a little further if I can stay focused

This was a test of the ability of brass tubes to conduct heat through the walls of the chimney. Chimney thickness: 1.5mm/1/16"

The tubes act as the fins that were mentioned earlier.

It's too bad you don't live next door to me so I could take this set-up over to your place to show how much heat is absorbed by the tubes. : )

Also check out the "Helly Kettle" in this thread : http://www.bplite.com/viewtopic.php?f=19&t=627&st=0&sk=t&sd=a Made by Allen, with a Heineken can and an aluminum beer bottle.

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[Rog Tallbloke]

Hi Dan. Thanks for the compliment, I took my design to some patent lawyers yesterday who think I may be onto something.

Specific gravity of Ethyl Alcohol at 20C is 789.20 so 15ml alcohol weighs around 12.7g. (Denatured alcohol varies in composition from country to country and brand to brand but usually contains around 90-95% ethyl alcohol)

Ethyl Alcohol has a burning capacity of around 29.5 Mega Joules per Kg (Methyl around 22.5MJ) and the specific heat of water is 1 calorie/gram °C = 4.186 joule/gram °C

If my math is correct it should take around 6.41g of denatured to boil 1/2 a litre from 10C if the setup is 100% efficient. This figure doesn't match that worked out by Sgt Rock. According to my way of working it out, my latest design is 56% efficient (And pretty fast too :-)
According to Sgt Rocks way of working it out my latest design is 75% efficient, which I don't think is really credible. I wish it was ;-)

Looking at your figures and thinking about how a slow burning stove heats the water I think as much as conducting heat the beneficial effect of the tubes was to hold the gases in the chimney longer so they had a chance to give up their heat before escapng. As I said before, the flame is reluctant to split, so you may have in effect been using one of the tubes as the chimney and the others as heat exchangers. I have made a kettle with an old cigar tube as chimney which works fine with a slow burner (A simple open tealight cup of denatured) but is too small to cope with a burner which gets through 12g in 10 mins or less. I reckon your test without the tubes wasn't so successful because your chimney was too big for the stove.

[Dan Yeruski]

Hi Rog, thanks for the weight conversion from ml to grams.

I'll have to go to Sgt Rock's site and cet a copy of his formula. Whiteblaze.net has one also that might help. I'll see if I can get you a link to it.

I'm finding it hard to comprehend whats going on with the tubes in the chimney. If the gasses are slowing down, would'nt there be some back pressure of a type that would cause a slower burn reat, extending the length of the burn time? Both tests had the same length of burn time.

The tubes are recessed about one inch from the bottom of the chimney. I believe the flame, once inside the chimney, is automatically centered by the incoming air that accompanies it. The air condenses it into a cone shape. Once it comes in contact with the tubes we can only speculate at this point what course it takes.

The tube I used as the chimney was of a size to fill the opening of the bottle. press fit. Tubes were chosen to be press fit also. Made things easy for me ; )

Thanks for your inovative design. I enjoyed pondering your design and learning from your experience.

[Rog Tallbloke]

Hi Dan, Fair point about the similar burn times, I guess your right that the tubes just act as heat exchangers. That's still less efficient than transferring heat directly to the water though, so try a stove which pushes the envelope of what the chimney can take without choking the flame. (you'll hear it guttering and/or smell the unburnt alcohol) To check the flame pattern, how about holding a piece of paper near the top and seeing where it scorches? I'd guess the flame would head for the biggest diameter tube, the path of least resistance. Having said that, if the output from your stove is low, it may be just hot exhaust gases that are reaching the tubes rather than still burning fuel vapour and oxygen.

Try a hotter stove :-)

[Dan Yeruski]

Hi Rog, I'll put the tubes back in and see if one is exhausting hotter than the others. I'll get a photo of the tubes befor I do another test to show you the discoloration that has occured from the heat.

[Dan Yeruski]

Tubes were returned and put to a test.

The two larger tubes exhaust the majority of the heat. I can hold my hand within 1/2" of the tubes for 8 seconds and not have to move it away because of the heat. Not much heat escaping.

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[Roger Caffin]

> I took my design to some patent lawyers yesterday who think I may be onto something.
Forgive my extreme cynicism, but may I suggest you compare the cost of the lawyers with the practical returns?

> the beneficial effect of the tubes was to hold the gases in the chimney longer so they had a chance to give up their heat before escaping
That would be my opinion too. The amount of heat transferred is proportional to the length of contact time. That is one reason the Kelly Kettle works well.

[Yukio Yamakawa]

<div>Outside of the 350 ml bottle
100 ml bottle inside
A difference, about 200 ml
Heat-resistant adhesive to the bottom of a fixed part and then punching them.</div>

fuel are alcohol ,Esbit,even wood

[Rog Tallbloke]

Nice job Yukio, looks good.

Roger: I'm filing a UK patent for free and then I'm going to produce some and see if they sell. If they do, I can get a 'first submission date' for a US and EU patent backdated to the UK submission date as long as I go for it within 12 months.

I got some free advice from some decent patent lawyers. ;-)

Boil time is now under 6 mins for 14.4 oz from 10C.

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