Post by Vortex on Jan 30, 2013 14:20:14 GMT -8
THE VORTEX STOVE
Metric Sketchup file (ver. 17) for 6" Vortex Stove
Imperial Sketchup file (ver. 17) for 6" Vortex Stove
Summer 2020 I built a 4" / 100mm scaled version:
donkey32.proboards.com/post/34699/thread
Summer 2021 converted the 4" into a dedicated cookstove:
donkey32.proboards.com/post/36456/thread
OVERVIEW
3 Chambers: Fire Box, Afterburner & Top Chamber.
All dimensions below are for a 6 inch / 150mm system.
To get the dimensions for other sizes:
4" / 100mm multiply by 0.666
4-3/4" /120mm multiply by 0.800
5" / 125mm multiply by 0.833
7" / 180mm multiply by 1.166
Firebox: 305mm / 12" High, 305mm / 12" Wide, 433mm / 17" Deep (not inc. the door frame or V-shaped floor).
Firebox Port: 50mm / 2" Wide X 175mm / 6-7/8" Long. (approx 50% CSA*)
Afterburner: 114mm / 4-1/2" High, 230mm / 9" Wide, 458mm / 18" Deep.
Top Chamber: 65mm* / 2-9/16" High X 280mm / 11" Wide X 470mm / 18-1/2" Deep.
(*Note: The 3 layers of the top chamber floor are there so you have room for adjustment by adding or removing pieces, as this is used to tune it to the mass and chimney, so allow enough room for this.)
Firebox should be made from cast refractory material. Ideally the mass of the firebox should not be so much that it leads to slow startups, but enough to help the coals burn up at the end. Best seems to be 45-50mm / 1 3/4"-2" on a 150mm / 6" stove (multiply by the above for other sizes).
Afterburner should be low mass and well insulated. I do not recommend using ceramic fiber products in any stove if you can avoid it, but if you have to, then enclose them so they are not releasing fibers into the gas stream. Insulating firebricks and vermiculite seem to be ok, but I recommend always using breathing protection when working with refractory materials.
Afterburner Shelf (roof of the Afterburner / floor of the Top Chamber). A gap of 110mm between shelf front and glass seems to be good, as it is large enough to avoid heat damage to the surface of the glass, but close enough that if the stove overfuels and smoke deposit is left on the inside of the afterburner glass it burns off clean again quickly. Make the glass easily accessible for cleaning.
Unless you are building the dedicated cookstove version then the roof of the afterburner should be made of an insulating or low mass material. Ideally I think a material that will glow as quickly as possible would be the best. I've used Vermiculite board or kiln shelves.
The roof of the Top Chamber in a cookstove may be a hotplate (ceramic glass, steel or cast iron plate) or the base of an oven.
Top Chamber: 65mm High X 280mm Wide X 470mm Deep, this low wide shape is important for the high surface area to volume ratio (SA:V), as that's replaced the stumbler. It's purpose is to create the back pressure that holds the vortex in the afterburner. The vortex is a balance between the push of the expanding firebox gases and the draw of the chimney, so make the top chamber easily accessible so you can tune it to your setup. The SA:V should be around 1.5, to calculate it measure the inside perimeter of the 1 CSA top chamber, eg: 65mm + 280mm + 65mm + 280mm = 690mm, then divide that by 471.3mm (the inside perimeter of a 1 CSA 6"/150mm round chimney pipe) 690 / 471.3 = SA:V 1.434. The Top Chamber Exit should be 1 CSA.
Air Supply: Primary 11" / 280mm wide X 1-3/8" / 35mm high at the bottom of the door below the glass, with a mesh diffuser screen on the inside, so the actual air supply is 20% CSA through the screen. This protects from sparks and diffuses and shreds the incoming air so it mixes with the firebox gases.
Bottom air: 1" / 25mm circular hole with round metal disk held over the hole with single bolt, so the disk can be turned to regulate the air. <3% CSA. Bottom air should only be used after the fire has peaked and until the embers are all gone.
V-shaped floor: ( donkey32.proboards.com/post/36830/thread ) This consolidates the coals and remaining fuel at the end of the burn, maintaining a high enough temperature for efficient combustion. It also guides the ashes into the ash-box underneath and allows for bottom air to come up though the embers during the coaling phase.
The stove runs best on full to 3/4 loads so better to make a size that suits this, you can do reloads so long as it's after the peak of the burn but before the start of the coaling phase, best done with a few larger pieces, not lots of small sticks.
Door construction: donkey32.proboards.com/post/20634/thread
*CSA = Cross Sectional Area. Example: On a 150mm system: (the radius) 75mm x 75mm x Pi (π 3.142) = 17673mm²
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UPDATE: This thread is now over 10 years old, the original stove was dismantled and a new one built.
Discussion of the new stove starts around page 15: donkey32.proboards.com/thread/703/vortex-stove?page=15
Building of the new stove starts on page 20: donkey32.proboards.com/post/23834/thread
2018 I started experimenting with a new Vortex style afterburner on the stove, discussion of that starts on page 28: donkey32.proboards.com/post/30273/thread
START OF ORIGINAL THREAD:
I recently stumbled across your great little forum and thought I'd share my stoves with you. The design is not classic rocket stove but includes elements of it. It's a horizontal front load, batch fed, mass stove with cook top. Now on it's 5th winter and going strong. ;D
With bypass flap open it can even be used as a classic open fire
The initial construction: I changed the top after the first trial - rising it another 3 inches and moved the bypass flap to the right hand side.
Two years ago I built another one for a friend who is a carpenter, and in return he made me a set of reusable wooden moulds to cast the refractory core in pieces that slot together. It was going to be tiled but hasn't happened so far. The door and ashbox (bottom right hand side end) has yet to be made - for a door he's still using the metal plate held up by a brick that I used for the first few years.
Top View (without metal top on): Firebox throat / riser on right, bypass flap opening to chimney in centre (flap not installed), contraflow down channel on left drops down below firebox level and travels around anti-clockwise under four bell chambers before exiting up the chimney (centre).
Some Videos Here
Vortex Stove Plans PDF
All Scans in Zip file
