Copper coil jet stove: video of boil test.

[Rog Tallbloke]

I made a simple version of a copper coil jet stove to see how fast they are and discover their quirks. Here’s the video I made of it in action. More exciting than the average alcohol stove :-)

If anyone is interested, I’ll say some more about construction. Main components are a single portion preserve jar, a piece of copper brake line and a piece of mop string.

400ml (13.5 fluid oz) of 14C water boiled in 4:47 using around 10g of fuel.

[DAN-Y/FANCEE FEEST]

They are interesting and dangerous.

[Rog Tallbloke]

I should have known better than to venture onto Dan Yeruski’s turf with an efficient, fast boiling and wind resistant alcohol stove design. :-)

Anyone who has seen a ‘Borde Bombe’ in action won’t be too worried by this design.

[James Marco]

While interesting, you will note that these are just another way to burn alcohol.
Alcohol is partially combusted already. Overall it has a low heat content compared with WG, Butane or propane. Assuming a clean combustion, WG is around 19500BTU/lb, Butane/Propane is around 20500BTU/lb. Alcohol is around 9500(methanol)/12000BTU/lb(ethanol.) Using glass can shatter in cold conditions, spraying alky all over, though it usually just creates a puddle of burning alky about 8″ around. I had this happen. Never used glass again, besides the weight.

Alky pretty much burns the same, regardless of the stove. A plain old cat stove works as well as some of the fancy concoctions. There is a minimum and maximum size for the flame, but it is rather forgiving anywhere in-between. The coil stoves have seen some proponents, and, there was a few threads about it 7-8 years ago.

[Bob Moulder]

How hot does the bottom (glass jar) get when it’s running full throttle with pot and windscreen in place? Pressurized alcohol stoves always give me pause, although I don’t personally know whether my concern is perhaps misplaced.

Safety concerns aside, I’ve seen these before but was put off by the weight of them and the BTU-per-weight for alcohol. It’d be cool to know the exact weight of the fuel… 10g is about 12.5ml, which is not super efficient for boiling 400ml. The time was pretty impressive considering there was no lid on the pot. Flames around the side of the pot represent wasted heat—this setup would benefit enormously from the use of a HX pot such as the Olicamp XTS.

Further testing with tighter controls would be interesting. Though I’m still pretty sure I wouldn’t take this into the woods.

[Rog Tallbloke]

James: “A plain old cat stove works as well as some of the fancy concoctions”

I’ve yet to see one boil 400ml in 4:47 or anywhere near it. Mind you, 4:47 is slow compared to heavier gas powered solutions I’ll admit. I’ve got my 2oz beer-can kelly kettle system down to 3:40 using alky burners inside and outside simultaneously. That’s not far off real world gas powered times, and doesn’t need a fancy (and heavy) finned pot to do it with.

“Using glass can shatter in cold conditions, spraying alky all over”

Yes. This is just a first attempt at a coil stove, using a quick and easy method. When backpacking, I don’t carry glass.

[Rog Tallbloke]

Bob: “How hot does the bottom (glass jar) get when it’s running full throttle with pot and windscreen in place?”

Not so hot that I couldn’t pick it up with my bare fingers immediately after the end of the test.

“this setup would benefit enormously from the use of a HX pot such as the Olicamp XTS.”

The flame spill only happened for a minute of so round the peak of the burn, so I couldn’t justify the extra weight of carrying a HX pot. It would be interesting to test it though, to see how much difference it makes to speed and efficiency.

“Further testing with tighter controls”

Won’t be done by me. I experiment for fun, and don’t have an equipped lab to work in.

 

[Ben H.]

Nice looking stove Rog!

Using my Stove efficiency calculator I made up some time ago I get just under 50% efficiency is a standard ethanol mixture which is not too bad.

I think a wind screen that comes up the sides more would increase your efficiency and decrease boil time.  Do you run the mop strings all the way through the copper coil?  My main safety concern would be pressurizing the glass jar.  Tetkoba (beautiful stoves if you never checked out his Youtube channel) designed a bunch of pressurized alcohol stoves that did not required a pressurized container.  His latest capillary stoves are still pressurized but I don’t think they operate at as high of a pressure as you do.

Interesting work.  Thanks for sharing!

[David Thomas]

I’m intrigued. Thanks for the post and the video.

If it can be picked up by hand (i.e. less than 140F) then HDPE could easily handle the temperatures, be shatter-proof, lighter, yet still translucent to see fuel level. Nalgene and others make 1- and 2-ounce capacity screw-top nalgene HDPE jars.

When they misbehave, what is the failure mode?

[DAN-Y/FANCEE FEEST]

I’ve designed a few and learned their quirks :-) and their dangers ;-)

The Borde Bombe is a different animal, has shut of valve ;-) apples and oranges ;-)

http://bplite.com/viewtopic.php?f=2&t=6343&hilit=coil+burner&sid=b7c761957c52815c18487033c73edb38

 

 

[Rog Tallbloke]

Ben: “I think a wind screen that comes up the sides more would increase your efficiency and decrease boil time. “

Agree.

Do you run the mop strings all the way through the copper coil?

No. Just up to the coil centreline. Mop string is a temporary measure until some fibreglass string arrives. It’s not so good, as it singes and makes a hard nub inside the tube.

My main safety concern would be pressurizing the glass jar.  Tetkoba (beautiful stoves if you never checked out his Youtube channel) designed a bunch of pressurized alcohol stoves that did not required a pressurized container.

Yes, I saw a couple of those on Youtube. It shows that there isn’t much pressure building up inside the reservoir. It’s mostly down to the expansion of vapour between the top ends of the wick and the jet.

His latest capillary stoves are still pressurized but I don’t think they operate at as high of a pressure as you do.

I made a couple of the capillary stoves. They work ok, but not as nice a swirling blue tornado as he gets!

[Rog Tallbloke]

David:If it can be picked up by hand (i.e. less than 140F) then HDPE could easily handle the temperatures, be shatter-proof, lighter, yet still translucent to see fuel level. Nalgene and others make 1- and 2-ounce capacity screw-top nalgene HDPE jars.

There’s always the possibility of burning spillage to consider. I expect it would probably be ok, and likely stronger than using beer can ends.

When they misbehave, what is the failure mode?

Dan Y is the man to ask, I’ve only made this one, and it hasn’t failed.

 

[Rog Tallbloke]

Dan Y: The Borde Bombe is a different animal, has shut of valve ;-) apples and oranges ;-)

Assuming you’re brave enough to enter the fireball to operate it :-)

[Colin Krusor]

Nice job on that prototype, Rog. Could a short, perforated metal tube be brazed or mechanically fastened to one of the copper tubes, over a fuel gas hole, to draw air into the flame, like in an alkane gas stove? If that would work, it seems to me that a higher boiling fuel, with better energy density, might be tenable (if good air mixing can be achieved, smaller and more numerous copper tubes are used, and the copper tubes are split at the ends and spread out in the fuel reservoir). I’m interested in your thoughts about using parraffin oil, higher molecular weight alcohols, olive oil, or coconut oil in some variant of this stove design.

[Colin Krusor]

Also, small fluoropolymer bottles (I’ve seen PTFE, FEP, and PFA) are readily available in many sizes. I buy them for my lab. Some of those will tolerate temperatures to 200 C (400 F), much higher than HDPE, and they’re translucent and impact resistant (and very inert, obviously). This, too, might be a candidate material for the fuel reservoir, if you want another alternative to aluminum to consider.

[Rog Tallbloke]

thanks for the observations and ideas Colin. I don’t know how much is to be gained from the air entrainment idea. The burn is starting in the right spot, just under the upper part of the coil, which as you can see introduces plenty of turbulence to mix air into the alcohol vapor.

Higher heat of combustion fuels scare me a bit, and are hard to obtain in the field (except unleaded petroleum (which is really scary, and stinky).

Paraffin and heavier oils like olive and coconut tend to like a lot of preheating before they’ll play. I did mke a hybrid stove which started with alcohol, preheating olive oil at the same time as achieving the boil, leaving the olive oil to do the simmering via a wick. It worked, but was a bit messy. They also require higher pressures to ensure atomisation as they exit the jet, which is beyond ultralite scope I think.

The special high temperature plastics sound good. I’d like to try them. Lab gear of that sort tends to be sold in high numbers though, or inflated prices for small numbers. let me know if you can offer any samples and I’ll cover postage plus a beer or two.

[Roger Caffin]

This is not a new design. One moderately popular version was the Handy Camper stove from the 60s and earlier. Is it any better than what we havve today?

This is a complete kit: stove, pot supports, pricker and lighting stick – and CORK. What’s with the cork you might ask. When you want to turn the stove off you jam the cork into the loop of copper tube, thereby blocking the jet. The flame goes out.

Ah yes, I forgot to mention: this stove does not run on wimpy alcohol: it runs on white gas!

Cheers
PS: yes, I have one. It works fine.

[Rog Tallbloke]

Fantastic, thanks Roger C. I love the smell of burnt cork in the morning.

Is that a brass tank or tin plated steel? Does the shroud around the coil actually touch so it conducts more heat back into the reservoir tank?

[DAN-Y/FANCEE FEEST]

The shut off valve prevents fuel from escaping. :-)

Commercial laboratory alcohol lamps had such a safety concern I had to file a report to the United States CONSUMER PRODUCT SAFETY COMMISSION. What I had discovered also applies to these DIY burners that Rog is playing with.

That cork Roger refers to is not to shove into the coil to shut it off. ;-)

The shroud is not for conducting heat.

from hikingjims site:

OK, let’s get started shall we? Now, since the Borde is a white gasoline type stove, we’ll need to prime (pre-heat) the stove. The directions say that one should open the valve (by rotating the “star” burner plate assembly to the left), turn the stove upside down allowing a small amount of gasoline to come out, and ignite the gasoline <i>while holding the stove in one’s hands</i>. Let’s see, holding a lighted container of <i>dripping</i> gasoline in one’s hands. Uh, is it just me or does this sound completely nuts? lol. There is a better way. First we’ll need the following set up: a bottle of alcohol, a small pan, and of course our Borde stove:

 

https://adventuresinstoving.blogspot.com/2011/02/stove-of-week-borde-stove.html

[Rog Tallbloke]

Dan Y: What I had discovered

Do tell.

[Roger Caffin]

Hi Rog

Brass tank of course.
The shroud on mine clips to the coil and does not have to touch the tank. It may gently do so, depending on the fit.

Hi Dan
That cork Roger refers to is not to shove into the coil to shut it off.
Funny about that. Yes, the instructions do say ‘blow out the flame and loosen the cap’. Well, as I said, I have actually USED this stove in the field and I found the idea of being able to blow the flame out is a bit of a giggle (once it is going). Naturally, you do not loosen the cap before extinguishing the flame. But quickly sticking the cork in the loop works every time. Yes, I think I have replaced the cork at least once.

Fwiiw: this ‘stove’ was made originally in the UK by Stesco. Then it was made in the USA, then it was made in Japan, then …

Cheers

[Rog Tallbloke]

Hi Roger C, Yes, I came across the Stesco original here after I googled your happy camper stove.

http://classiccampstoves.com/threads/stesco-coil-burner-petrol-gasoline.9866/

Britain innovates, the world imitates. dangerous Hawker-Harrier VTOL aircraft, dangerous camp stoves, you name it…

The cork to put out the flame is a sound plan. Just carry a spare to stopper the stove with when cold.

It’s almost giving me the courage to try a gasoline version. I’m thinking you could use modern materials like carbon felt and the poorly conducting plastics Colin mentioned  to regulate it to some extent. Somewhere in the design you’ve got to bridge hot coil to cool fuel.

[Roger Caffin]

Somewhere in the design you’ve got to bridge hot coil to cool fuel.
There are 1 or 2 bits of cotton wick going from the fuel to the copper tubing of course. I have NO idea how they get it in there!

Cheers

[James Marco]

Well, time is never of primary concern with Alky stoves. While working on a HX pot I did many burns of 16oz(2 cups or around 473ml) of 40-45degree water in about 5:15 or so with .625oz of fuel. Like I say, alky all burns about the same for most camping stoves, at least within the tolerance of my testing with many different types of stoves, including the coil stove. Note that this is actually a better time to boil, considering you started at 17C, not 5C, your test did 406ml, not 473, and the fuel consumption (18-19g) was about the same. But, I also had it in a cone. I would say it was roughly the same using the 12/10, though I did need to add an air space under the cone or a simmer ring slowing it down to get a decent fuel consumption.

I was hoping to produce a UL version of a WG stove, since canisters were not widely available in much of the ADK’s…mainly larger stores. However over the past 5 years, this has changed. Even the typical general store stocks a few, nowdays.

At the time, I was looking for a smaller(about the size of a cup,) lighter (<4oz,) and, reliable (works in all weather, hot or cold) stove that would burn WG/Kero. None of these worked well without some sort of regulator valve adjusting for temp, of the outside and the stove. Even the Borde Bomb was too heavy.

[DAN-Y/FANCEE FEEST]

Rog Tallbloke wrote:

I should have known better than to venture onto Dan Yeruski’s turf with an efficient, fast boiling and wind resistant alcohol stove design. :-)

Anyone who has seen a ‘Borde Bombe’ in action won’t be too worried by this design.

Yours is not wind resistant as is ;-)  What have you discovered about how it reacts in the wind in actual field tests?

HikingJim seems to be concerned about the safety of the Borde bombe:

<span class=”postbody”><b>A word of caution:</b>  Since the burner is directly attached to the fuel tank, the Borde stove gets <b>hot</b>.  Always pick up or move the stove by the wire holder.  It should be noted that <i>the Borde stove has no safety devices of any kind whatsoever</i>.  Overheat this stove, and it will explode.  Indeed, the nickname of this stove is the Borde Bomb, although some claim that the nickname derives more from the method of priming than the way in which the stove operates.  The plug at the base will sometimes fail first, but the plug failing first may not always happen.  In short, <i>you </i>are the safety device.  It is up to you to turn down the stove if it seems to be surging too powerfully.  You must be mindful at all times of how the stove is sounding and performing. </span>

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