Vortex Stove

[Vortex]

Dec 2, 2022 10:54:59 GMT -8 bibo said:

Thank you Trevor for reply,

Can you please tell me, when you were pouring concrete, did you follow drying and heating procedure, or it can be skipped?

Company I have contacted for buying refractory cement (finished mix) provided me with strict rules of taking care of curing concrete. They say that in order to get good product, it need to be moistured every hour for 24 hours, then let dried for 3 days, than kept for 24 hours at 150 degrees C, than slowly adding temperature until it reaches stove's operating temp. Since I can't do that, I am thinking to order from them custom sized refractory bricks, which would be same size as concrete slabs.. What you think?

Hi bibo,

I follow the instructions on the bag of the brand I use. I keep it covered for the first 2 days, then a day or 2 uncovered before removing it from the mould. I let them dry slowly in the house and when first firing start with a small fire the first time, gradually getting hotter over a few burns.

Trev

[bibo]

Thank you Trevor,

I will try my luck than that way.

I will put my progressing and photos here.

[bibo]

Trevor, 

I am searching, but can't find.

Is there any reason why you used calcium silicate boards for firebox insulation, and not vermiculite for example? I understood you were avoiding CFB, just I wonder why not vermiculite? 
I bought vermiculite boards for afterburner, and calcium silicate is easy avalaible, but since you said they react with steel a little, I started to consider vermiculite for firebox.. Or calcium silicate has better insulating properties?

[Vortex]

Vermiculite board would be fine for the firebox insulation. The Calcium Silicate board was the cheapest option at the time and vermiculite board was not available locally here. I haven't looked up their relative insulation values though.

[jonasp]

I'm about to order the materials for the core at the moment I'm planning to built the firebox out of firebricks, afterburner the walls of insulation firebricks, the shelves of the afterburner out of Vermiculite board.
The website I'm ordering doesn't have firebrick boards to make the roof of the firebox, would Vermiculite board be as good (25mm thick) or would you advise against that?

An oven (built out of firebricks) will be placed on top of the afterburner but I'm not sure if I should make the roof of the afterburner out of Vermiculite board to have a better? burn and warm the oven because it'll be at the top of the bell or have the roof of the afterburner also made out of firebrick boards (which i would need to source from somewhere else). I'm leaning towards Vermiculite board since I'm guessing it would already have high enough temperatures.

[Vortex]

Only time I've used vermiculite for the firebox roof was on my outside test stoves and they were not used many times, it can take the heat but is prone to physical damage when loading. If you can get kiln shelves they can be used for the firebox walls and roof.

[awan]

I have made the vertex stove hight 8", width 9", deep 9" afterburn hight 4" wide 6"

Problem is stove not forming vortex. I have a pot hole directly over vortex.

[Vortex]

Your dimensions seem all wrong. Afterburner chamber width should be twice the height - 4" high by 6" wide wouldn't have enough room to form the vortex properly, so no surprise there.

[victorlt]

Nov 27, 2022 11:11:53 GMT -8 Vortex said:

Hi jonasp, To my knowledge no one's built a 180mm Vortex core yet so it would be a first. The ISA sounds like it's about the max, I wouldn't go much bigger. If the oven is inside the bell I don't think it would make much difference, though I'm no expert on that side of things.

Install a bypass, they're great for use while the door is open, like when you're lighting it or if you need to open the door while it's running, that's the only times I use mine. I wouldn't bother with secondary air to the afterburner, if the rest of the stove is correct you shouldn't need it. I would recommend the ashbox below with a small amount of air up from below for the latter stages though.

Trev

Hi Vortex,

There is one 180mm core already After many test burns and modifications I finally build it! This is 180mm system which I adopted to my sauna stove. I'm very happy with final result:

youtu.be/5jvqq12aK5s

[Vortex]

Thanks for sharing your video victorlt

Great to know there's a successful 8" Vortex stove out there now. The vortex looks like a perfect clean burn in that clip. What modifications did you make to the design?

[awan]

Dec 19, 2022 12:03:41 GMT -8 Vortex said:

Your dimensions seem all wrong. Afterburner chamber width should be twice the height - 4" high by 6" wide wouldn't have enough room to form the vortex properly, so no surprise there.

But I got that dimensions from this thread.
Here is the link to that dimensions
paste.pics/KJH32

[awan]

I am basically looking for fuel effective cook wood stove we put our pot on directly fire. Its not a big deal but I am in search of stove that should be smokeless and fuel effective. If I can have 2 pot spaces on stove that will be extra edge.

[Vortex]

Only the width of your firebox and afterburner are the same - For a 4" you have a very short firebox and the afterburner much to high, it should be 3" / 75mm.

Do you have the top chamber like in that drawing? The later cookstove version would be better for you:
donkey32.proboards.com/post/36456/thread

[victorlt]

Dec 20, 2022 5:34:33 GMT -8 Vortex said:

Thanks for sharing your video victorlt

Great to know there's a successful 8" Vortex stove out there now. The vortex looks like a perfect clean burn in that clip. What modifications did you make to the design?

First of all thank you for sharing your idea and knowledge - it is really great and nice idea. If shortly, I have spent almost a year from I found this forum last winter till the stove design I'm running now. Probably like most folks here I also started from the test 125mm core which I made from vermiculite boards. Following your measures the core alone without heat exchanger run perfectly from the first run. But when I started tests with 250kg stones load in heat exchanger, it started to fail. Soot, overfueling, full chamber of charcoal - it's just a few well known issues I faced with trying to heat up this mass of stones. At some point I was giving up with decision that this type of burning is not suitable for such sauna stove design I'm trying to build. But day after day making small changes I finally started to get nice runs. After intensive autumn session (1-2 burns a day each day), finally I found balance between burning core and heat exchanger design which works exceeding my expectations. The main changes I made to the burning core comparing with yours are:

1. Higher firebox with flat floor (without V-shaped floor). Because of sauna stove specifics, till I reach 250kg of stones mass till the glowing red stage, I need to run stove 2-3 hours adding 4-5 loads of wood (20-30 kg of wood) . So if the firebox is V-shaped and square, after 3rd load all firebox is full of charcoal and there is not enough space to add more than 3-4 small pieces of wood. It leads to long stones heating time, frequent wood loading, overfueling. Also when the sauna stones are ready and gasses burn stage is over, charcoal from firebox is then removed to prevent any possibility to carbon monoxide poisoning.
2. Air supply from firebox sides. Biggest part of air I give from firebox bottom left and right sides and just a small part from the front (over holes in firebox door and floor near to door, to prevent glass from getting in soot when starting the stove). This air supply design doesn't allow air "jump" over the fuel pile and reach the port in a short way. I also noticed that such air supply also reduces the charcoal burning time.

3. More primary air. If to use original Peters and your configuration (20-25% of CSA primary air and 25-30% in total with secondary) means that stove can take ~ 1 wood load per hour. Despite very effective burning, converting this wood mass to the calories which I need to heat up stones in such conditions leads to a very long stones heating time - 4-5 hours, which is out of my target 2-3 hours time. The box full of stones seams to be very effective heat exchanger and can take more calories during the same time than 180 mm system can offer running it in conservative manner. So I decided to try speed up things a little and increased primary air up to 35% with possibility to close 5% on the firebox doors inlet. You already know consequences of that increase, but this was breaking point of my system design. More primary air in many cases destroy vortex and causes overfueling – this is what I got at first. Solution follows in next points.

4. Secondary air inlet from the port left ant right sides, 8 % of CSA. Secondary air in my design seams to be essential. After 1-1.5 hour of burning, when adding bunch of would in a glowing firebox it starting to generate amazing amount of gasses and first 10-15 seconds just a flickering gasses flow is seen in the secondary chamber. When closing the door, temperature in firebox rises up and air flows finds its way to the secondary air channels, vortex appears again, it clearly seen that secondary air holes ignites the gasses coming from firebox while middle of the port is fully taken by the gasses flow.

5. As you see, I’m using around ~43% of CSA air in total (35% primary and 8% secondary). This amount speeds up burning process in firebox, but because of ballast gasses can destroy burning efectivenes and kill the vortex at all. So this point brought thought – why not try to get rid of ballast gasses instead off letting them to pass over the port? After few test burns I finally stayed at the 10% of CSA in total leaving two vertical holes at the firebox end in the bottom trough which ballast gasses directly enters exhaust duct. This configuration in conjunction with points No 3 and 4 gives very stable and powerful burn even feeding stove with not ideally dry wood, vortex remains stable even when I add wood with remnants of snow and ice from wood bunch outside. Stones in the heat exchanger starting to glow after 2 hours of burn and stove is ready to serve gourmet “Löyly” for sauna visitors 😊

p.s. All conclusions above are based on my subjective opinion and may not work for you due to different circumstances, stove materials and overall configuration. I don’t have any analyzer like “testo”, and all tests I done are evaluated by myself empirically and visually. Hope this will useful for someone or will ignite some nice ideas 😉
drive.google.com/file/d/1nuFRdzb3XFz20At5XcQgx5Uk_nl7AP6C/view?usp=share_link

[awan]

Jul 20, 2021 5:04:13 GMT -8 Vortex said:

Last year for my summer project I made a scale 4 inch Vortex stove:



donkey32.proboards.com/post/34699/thread

This year I decided to try adapting the design to make a dedicated 4" cookstove. We often get people coming to the forum asking for small cooking stove designs for the 3rd world, and I've been wondering how well this would work.

To adapt it to a dedicated cookstove I wanted the hotplate above the port, as the main difficulty I see with getting heat into hotplates is the problem of laminar flow, where a layer of air separates the flame from the metal plate.

I removed the top chamber and cut some small pieces of vermiculite board to make the side and back walls of the afterburner. The top is now the hotplate and the exit of the afterburner is to the right and left sides (65mm wide x 75mm high). The chimney was the same as previous.









The increased resistance of the double exit channels seemed to have the same effect I observed on my 6" stove when I increased the surface area to volume ratio for the top chamber (Page 56).

The little cookstove ran excellent, the vortex stayed doggedly in the afterburner the whole burn. The fire ran for over an hour on the kindling I'd usually use to light the 6 incher. I boiled several large kettles of water on the cooktop while it was running.

What are the dimensions of this vortex cook stove?
When you say 4" or 6" stove, 4" refer to what?