Vortex Stove

[Vortex]

Nov 9, 2022 18:57:56 GMT -8 ankitg said:

Hi Vortex ,

Your modification is good it seems for the cooking directly on top of the port. Was this test done with secondary air or you ran with just the primary air? I suppose with secondary air it would be more efficient. martyn used this design (youtube link to his stove video www.youtube.com/watch?v=UH-0D9Tb6dQ) and his works quite well it seems with secondary air.

I will be building a similar with your design. Will try to post pictures/video once its finished.

Thanks,
Ankit

It was done with just primary air. I've done many test burns with the analyser on the inside stove with and without secondary air. The main benefit was when the stove was overfueling, and it only did that if there was not enough back pressure in the form of contraflow channels, mass, bell and/or a high surface area to volume top chamber. Overall I came to the conclusion that secondary air was unnecessary if the rest of the system was well tuned. I still have it available on my inside stove but only ever use if it starts to overfuel, which is rare.

When the stove is overfueling, apart from the extra heat from improved combustion, more air carries the heat farther through the stove, which would explain why it increases Martyn's hotplate temp, but any more air than the stove needs for complete combustion just reduces efficiency by transporting heat through the mass and out the chimney.

[damian90k]

Hi,
I would to make stove similar to Martyn. Is here any post that i can see dimensions of his stove?

[ankitg]

Hi Trevor! (Vortex!, I hope I got the name right!)

Thanks for the response. 

Interesting to learn about your experiences with over fueling / secondary air and fine-tuning. I have only started experimenting with vortex rocket stoves. I have built one using Loz Harrop's design with a view of cooking pizza at 400 degC. It works quite well, very very clean. Yet to build the actual pizza oven to go on top of it - will do that at some point.

This 4" vortex stove design is quite different and its seems more practical for regular usage. Here in India we like stoves which are closer to the ground so that cooking can be done sitting down. So this design appeals to me because there is no vertical riser like that in traditional rocket stoves. Peter says that with vortex port being horizontal and no vertical riser its not actually a "rocket" stove. May be not - I don't think it matters as long as the result is high heat, complete combustion and high efficiency.

I am planning to put a cast-iron plate 18" x 18" on top of the top-chamber. My current planning is to put a 6-7" hole (and lid to use it when desired) in the cast iron plate with an option to put the vessel directly on the flames/vortex coming out of the port. Not sure how well it would work - I don't know if slight air-gaps between the cast iron plate and the vessel would impact the vortex stability and its efficiency. Will have to experiment and see I guess. 

Will try and keep you updated with my trials once I get a chance to build my version of your 4" design. 


Thanks,
Ankit

Nov 10, 2022 6:39:34 GMT -8 Vortex said:

Nov 9, 2022 18:57:56 GMT -8 ankitg said:

Hi Vortex ,

Your modification is good it seems for the cooking directly on top of the port. Was this test done with secondary air or you ran with just the primary air? I suppose with secondary air it would be more efficient. martyn used this design (youtube link to his stove video www.youtube.com/watch?v=UH-0D9Tb6dQ) and his works quite well it seems with secondary air.

I will be building a similar with your design. Will try to post pictures/video once its finished.

Thanks,
Ankit

It was done with just primary air. I've done many test burns with the analyser on the inside stove with and without secondary air. The main benefit was when the stove was overfueling, and it only did that if there was not enough back pressure in the form of contraflow channels, mass, bell and/or a high surface area to volume top chamber. Overall I came to the conclusion that secondary air was unnecessary if the rest of the system was well tuned. I still have it available on my inside stove but only ever use if it starts to overfuel, which is rare.

When the stove is overfueling, apart from the extra heat from improved combustion, more air carries the heat farther through the stove, which would explain why it increases Martyn's hotplate temp, but any more air than the stove needs for complete combustion just reduces efficiency by transporting heat through the mass and out the chimney.

[Vortex]

Nov 15, 2022 4:14:28 GMT -8 ankitg said:

I am planning to put a cast-iron plate 18" x 18" on top of the top-chamber. My current planning is to put a 6-7" hole (and lid to use it when desired) in the cast iron plate with an option to put the vessel directly on the flames/vortex coming out of the port. Not sure how well it would work - I don't know if slight air-gaps between the cast iron plate and the vessel would impact the vortex stability and its efficiency. Will have to experiment and see I guess.

Hi ankitg, I don't think you'll need the hole in the hotplate for direct flame contact to the cooking pots. The hotplate gets very hot and is very efficient at transferring the heat through to the pots, also means the bottoms of the pots stay clean.

Let us know how it goes.

Trev

[bibo]

Hi everybody!

I am new to building stoves. First I heard about rocket stoves many years ago, then recently stumbled to Peterberg's page and got hooked up to build a batchrocket stove how he do. Thanks to him, I came to this forum also, on these wonderful stove. I love Peter's design and how stove works, but after I saw Vortex's vortexes on video, I want to try to build it. Because it is so long thread, it is little hard to follow everything, so I hope here I can again ask things what was already asked. First question is if somebody can put again the sketchup link because neither from the first page works for me. I press it, and it open a new window and close it immediately..
Other is, Has it in the last version, after drilling holes in vermiculite for secondary air, vermiculite stayed with wavy surface in the top chamber, or I can use it flat, because where I can get vermiculite, it comes just flat?

PS: I put my hat down to ground for fantastic work Vortex! And many thanks for publishing it! I hope soon I will be able to donate a little to your account.

[ankitg]

Hi Trev,

Thanks for the response.

Normally I wouldn't think about cutting the hole in the plate - especially when one has the option to keep the cooking vessels clean. But you see, one traditional Indian cooking vessel is a curved pan made of clay - its used to roast Indian flat breads of different kinds. Now these clay pans are handmade and comes in different sizes and no particular curve-radius. So I thought the easy way to use it would be to set it in a hole slightly smaller than the curved pan itself which would ensure appropriate heat distribution to the pan. Also, to cook pearl-millet flat breads on these pan require higher heat - I'd say around 270-290 degC uniformly to get the perfect bread. 

If I can device a method to uniformly heat the curved clay pan without a hole I'd go for that - but until I carry out some test runs I have little clue. May be a 1/4" thick metal ring of about 1" width and diameter similar to clay pan which would encapsulate the edges of the curved vessels and trapped the heat from the cast iron plate and provide good uniform cooking temperatures.

I'd welcome any inputs in the matter. 

Thanks,
Ankit

Nov 16, 2022 2:23:51 GMT -8 Vortex said:

Nov 15, 2022 4:14:28 GMT -8 ankitg said:

I am planning to put a cast-iron plate 18" x 18" on top of the top-chamber. My current planning is to put a 6-7" hole (and lid to use it when desired) in the cast iron plate with an option to put the vessel directly on the flames/vortex coming out of the port. Not sure how well it would work - I don't know if slight air-gaps between the cast iron plate and the vessel would impact the vortex stability and its efficiency. Will have to experiment and see I guess.

Hi ankitg, I don't think you'll need the hole in the hotplate for direct flame contact to the cooking pots. The hotplate gets very hot and is very efficient at transferring the heat through to the pots, also means the bottoms of the pots stay clean.

Let us know how it goes.

Trev

[ankitg]

Hi Trev,

I am about to complete the top-changer layout. 

Photo link: drive.google.com/file/d/16frJa9suf3JNwUonfWI5EtRgOJse39VN/view?usp=share_link

I am working with 9" x 4.5" firebricks for the top-chamber vertical walls as I have no access to vermiculite boards. Your design specifies top-chamber height as 75mm and I wanted to verify if that requirement is absolute or is there some wiggle room there? If I use the bricks as it is then the top-chamber height comes to 4.5" --> ~115mm. If this requirement is an absolute then I'd have to take 40mm off these bricks and bring them to 75mm as specified in your drawing. 

Kindly let me know so that I can proceed accordingly.


Regards,
Ankit

Nov 16, 2022 2:23:51 GMT -8 Vortex said:

Nov 15, 2022 4:14:28 GMT -8 ankitg said:

I am planning to put a cast-iron plate 18" x 18" on top of the top-chamber. My current planning is to put a 6-7" hole (and lid to use it when desired) in the cast iron plate with an option to put the vessel directly on the flames/vortex coming out of the port. Not sure how well it would work - I don't know if slight air-gaps between the cast iron plate and the vessel would impact the vortex stability and its efficiency. Will have to experiment and see I guess.

Hi ankitg, I don't think you'll need the hole in the hotplate for direct flame contact to the cooking pots. The hotplate gets very hot and is very efficient at transferring the heat through to the pots, also means the bottoms of the pots stay clean.

Let us know how it goes.

Trev

[Vortex]

The dimensions are important, the afterburner will not form the vortex properly if it's that high, and the surface area of the top outer channels create the back pressure that maintains the vortex in the afterburner. Being made of dense firebrick splits just means the afterburner will take longer to get up to temperature.

[jonasp]

reading through the this thread is making me more inclined to make my mass heater with a vortex core, thanks for all the information sharing and testing!

I was wondering if I could keep the ISA of the RMH (180mm for 7.6m2)? Should I install a bypass anyway for a better start up?
I wouldn't use a cooktop on top but might install a oven in the top part of the bell, do I just add the ISA of the oven in the total ISA?

I would skip the secondary air since my interpretation of your testing would not really benefit the storage of more heat.

[Vortex]

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

[bibo]

Trevor,



I have read all thread few times, and made lot of notes, but still don't have all answers.. Can you please tell me which insulative firebrick did you actually use for afterburner?

There is more choices when I search, and I have no idea what to choose.



Here is example of bricks offered when I search for insulative firebricks:



-Mullite Insulation Brick



-High Alumina Insulation Brick



-Fire Clay Insulation Brick



-Diatomite Insulation Brick

[Vortex]

Hi Bibo, These are the IFB's I used for the afterburner:

dineensales.com/ShowProduct.aspx?ProductID=20

[jonasp]

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

Thank you! Looking forward starting the build and sharing it on this forum.

Have you or anyone else tested the different primary air intake positions, in the middle of the door sides or would that roughly have the same effect as the mesh which causes more evenly spreading of the air?

I'll implement the ashbox air intake.

[Vortex]

I've tried it all around the door, best seemed to be a long narrow one right across the bottom. I only open it enough to get the end of my index finger into though:

[bibo]

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?