Vortex J tube update

[martyn]

I have recently updated my vortex J tube with a glass front and top, very easy and forgiving to use.

[fuegos]

That looks great Martyn , i love that glass firebox top/front.Does the riser just sit on the burn tunnel or is it held in place with some fixing ? Do you seal the top or does it just sit on the fiberglass rope ? I imagine that being screwed down it's pretty airtight. Same question about the cooktop - just a piece of ceramic glass over the hole ?

[martyn]

Hi Fuegos, yes really simple design but works really well for my use, like a burning dustbin without the smoke as it will burn virtually anything that will fit in under the lid.
The riser simply sits on top of the ceramic burn tunnel, the coiled up ceramic mat protrudes enough to make a good seal.
The glass front and lid are simply made from vermiculite, ceramic glass and titanium exhaust wrap held together with silicone and aluminium tape. Even the hinge for the lid is just a piece of exhaust wrap siliconed in place.
The steel top is screwed down and the hole has a bit of glass to cover it but I can remove the glass and put my wok directly over the heat riser for cooking.
Also I have a small mirror fixed to the chimney that reflects down the riser so you can see the vortex... just for fun!
There is a secondary air inlet between the glass top and the barrel.
The fire box is a little bigger than standard at 10” x 7” x 12 “ high.
I can make a more detailed video if you are interested.

[Vortex]

That's nice Martyn. Is the burn tunnel offset to create a single vortex?

patamos made something similar a few years ago:

[martyn]

My previous design used a more complex tunnel and shaped vortex but this one is really simple with just a piece of ceramic fibre blocking off one half of the burn tunnel..
I tried it with a double vortex as well and no vortex at all, all versions seem to work but i settled on the single vortex as it seems to start very easily.
I have used a piece of glass along the top of the tunnel to carry the secondry air, it might not last or perhaps the fresh air will keep it cool enough to last?

[fuegos]

Apr 4, 2021 3:41:43 GMT -8 martyn said:

I can make a more detailed video if you are interested.

A rough sketch with sizes would be great , but yeah a video would help a lot.I'm thinking about building some sort of J for outdoor cooking , no barrel or mass , just a hotplate on top of the riser .The vortex bit of this build is interesting to me , not sure about CFB , not that i have any doubts , just that i have firebricks and clay at hand.The door looks really neat , the airwash idea looks like it could be adapted for other batch box designs ?

[martyn]

The air wash works perfectly so far, the vortex is fun to show folk but i cant say if it has any benefits over a standard J tube.
I can tell you that a bigger fire box and a lid will extend the burn time, the overall design is easy to operate and very quick to heat up.
The temperatures on the barrel are impressive, the hot plate average temperature seems to run around 400c in the centre and 220 around the edges.
I can push the temps way over that though with 580-590c frequently seen!

I can easily access the fire box as the front glass is a drop in unit, so I have tried many configurations like the vortex restriction or a double vortex just by sliding in a piece of ceramic fibreboard.
However I have only just played a little bit as its current format is way past my expectations and requirements.
Possibly the most different aspect is the piece of glass in the roof of the burn tunnel, it is a continuation on the P channel that runs 100mm down the fire box and has a 5mm gap.
I dont know if this is working to my benefit or not but it seems to work!

[fuegos]

"I can easily access the fire box as the front glass is a drop in unit " something that is useful for cleanout i guess ? we're 100% offgrid here & don't have a vacuum cleaner so any build has to cleanable by hand .I guess your design could be just as easy copied in steel plate for the top/front as i'm guessing it won't get hot enough there to cause spalling .

[martyn]

A bit of an update, I have taken out the little vortex restriction just to see if there is any difference in performance.

It does not actually make much difference overall but there are several notable changes, the top does not get so hot, after about one hour of burning the top is reading about 420c where as with the vortex I was seeing around 500c .
However it seems to just lite up really easily and get to 350c in just a few minutes but the glass top is probably more lightly to make those sort of differences ?

Not a very good experiment as I changed several things, it is really easy to just slide in the vortex restriction so I will do that in the near future …

[Orange]

nice upgrades! Unfortunately the flames don't shoot out of the riser for more spectacurlar view.

[martyn]

I have been wondering about that, if I can reduce the insulated riser and replace the top third of the riser with some glass it might still draw well enough and make a better display?

[martyn]

New video showing how a very basic modification can alter the effects!

[satamax]

Nice Martyn.

Well, if ever you want to tinker further with the idea. One day. I think making a conical heat riser, with a edge burn tunnel (neutral vane), like a dust extraction cyclone. Making a big chamber at the bottom, and CSA at the top. could be interesting.

What gave me the idea.

billpentz.com/woodworking/cyclone/cyclone_plan.php

[martyn]

Hi Max, it all about finding the time nowadays, I would love to experiment some more but this version is so easy going and suits my needs.
Also my partner gets really fed up every time I rip down a perfectly good and well functioning project!

[satamax]

Oct 2, 2021 10:33:12 GMT -8 martyn said:

Hi Max, it all about finding the time nowadays, I would love to experiment some more but this version is so easy going and suits my needs.
Also my partner gets really fed up every time I rip down a perfectly good and well functioning project!

I can get that. I have nearly been the cyclonic path. Well, i did a J with a "neutral vane" and an expansion or tornado chamber behind. But it wasn't conical. The top of the chamber ; a gas bottle, sagged under it's own weight after a while.

Then i discovered Peter's batch.