Vortex Stove

[martyn]

[pianomark]

Martyn,

You should be aware that if ceramic glass is not allowed to shed heat, it may fail in high temp areas. It has happened to me and I've heard others here say the same. It might last a while, but be careful not to create a situation where failure might be catastrophic.

Just sayin'

[martyn]

Hi Mark, thanks for your concern and interest, the stove is still in an experimental stage but it seems to be that ceramic glass is not suitable as a cooktop in my situation anyway.
The internal pieces may or may not last but that is what experiments are about.

[Vortex]

Hi Martyn, Bottom air (tertiary air) should only be used from the start of the coaling phase, if you use it from the start of the burn it will cause the fire to overfuel as you saw. It increases the production of gas overloading the air supply, and makes the fire burn down into the stack of fuel towards the source of the air. The primary air is best directed towards the base of the front of the firewood, secondary air in from the sides and top. What were your stumbler and exit sizes?

[martyn]

OK that makes sense, I will change things around for tomorrow, 52% and 70% for the ports.

[patamos]

Feb 3, 2021 23:20:58 GMT -8 martyn said:

i also wonder why my barrel and mass is not getting that hot, perhaps the ceramic glass is shedding too much heat, I might try placing some insulation over it ....

When i want to shed less heat off the ceramic glass top i sprinkle a 1" thick layer of 3/8 coloured pebbles.  This slows the radiant harvest/loss somewhat and makes for a nice aesthetic.  Some of the rocks pop the first few times it gets hot but eventually they stop.
Of course, this method depends on having a perimeter that is a bit taller than the cook top.

I've never tried putting the cooktop-glass in the shoebox innards, but I know that clear ceramic glass starts to crystalize and destabilize pretty quickly at those temperatures.  You might get a season out of it before it crumbles.  But no harm done...

[martyn]

Thanks patamos, I can see how ceramic glass could be used in many different configurations as its characteristics are great for fast space heating.

I managed two fires today and I think I have cracked it but, equally important is I now have a much better concept and understanding of how the stove worked and behaves.

First fire was really successful with no blackening of the glass and super hot cast iron plate of 570c but quite a short burn time with the vortex showing for only 45 minutes.
I put back the slopping floor and turned the pre heated air to point straight up alongside the door frame, the ports were the same as yesterday.

Second burn, I also removed the stumbler and reduced the exit port to 65% this seems to be a great setting for me as the vortex jumped up within a few minutes and stayed active for 1 hour 15 minutes and another 20 before it completely died, no smoke and around 470 on the cast plate for over an hour!

I am going to take it all apart tomorrow and re configure the design of the barrel arrangement as the oven idea does not really work and the whole thing is to ugly for me.
So I will probably be back to square one and have to set it up again but luckily I am quite happy to do so....
It will take a few days to do what I have planed but I will keep you informed ......first I need a new barrel during a full lock down and that might not be easy !

[patamos]

Sounds like a fun experiment in many ways.
During the rebuild I think you could also add a lot more harvesting mass without any trouble.
Maybe inside the barrel, maybe a surround bench... maybe a steam powered water park... all kinds of possibilities

[martyn]

The stove is built on top of a a 2.4 x 1.2 x 100mm slab of concrete sitting on top of 100mm of polystyrene as well as the low concrete walls, so a fair bit of mass.

I have not got very far, however I will have a new barrel by the weekend and hopefully much more of the other things I need to progress.
I have a plan to supply a pre heated main air supply, I found out with my last stove that pre heated air can really make a difference!

Re the steam, yes I have loads of ideas for adding a bit of fun to the stove including steam effects, sterling motors and other moving parts.....

With my last stove, I had intended to make a turbo by forcing hot air into the fire powered by a stove fan in turn powered by the heat of the stove top....just for fun you understand ... Just never found enough time in the day!

[martyn]

I am still hammering away with the stove.. l mean that literary ... I have never done so much metal working before!
Unfortunately we are still in full lockdown so I simply cant get anything finished, I want some high temperature paint but even amazon wont ship such things to our island!
However it is up and running, I lit the first fire yesterday only to see puffs of smoke appearing in various spots due to my terrible metal working skills.
It did heat up though and put on a nice display unfortunately including the same issues with a smokey glass at around 20 mins.
I will be at it again today to see if i can find the magic settings.....

[Vortex]

I was just wondering how you were getting on with it. It either needs more air or more resistance. If it still overfuels with the door cracked open 4 or 5mm, then the top chamber exit port needs to be smaller. Are you still running it without a stumbler, that would also exacerbate it?

[martyn]

The main difference now is the exit is in the roof of the top box and is now centre of the barrel about 78mm under the hot plate.
So basically I have slid the stove into the barrel so the face is sticking out about 150mm.
I have made the exit adjustable and I can actually adjust the exit while the fire is running.
The main air is supplied via a 85mm flexible pipe that does one circuit inside the barrel but I can also supply via the vent under the door which is now max 135 x 30 but easily adjusted to be smaller.
One thing that is interesting... if I open my bypass, giving a very direct route up the chimney, two thing happen very quickly, the internal chimney temperature at ceiling height jumps up from 65c to 250c and the vortex actually bounces off the viewing window!
Very psychedelic and a bit scary ha ha!
If I reduce the exit to around 65% the stove works very nicely with the door wide open when the fire is raging but let’s out smoke as soon as the fire dies down.
It is doing a good job of heating the room and the hot plate is now a more even and constant 330c for an hour or so.
I will keep playing for a few days and report back....

[Vortex]

Sounds like you should have plenty of air now, so I'd try some more resistance in the top chamber. Adjusting the end port while the fire is running wont instantly show you if a change is better or not, as the fire needs time to adapt to the new level of resistance, so give it a while. The effect you see when opening the bypass is exactly what I get. The vortex is a balance between the push of the fire and the draw of the chimney, changing either will affect it. Find the right combination/balance that keeps the vortex spinning in the rear of the afterburner and it'll burn clean.

[martyn]

I had formed a 150 x 150 square hole in the ceramic glass that is 75mm below the hot plate, there was a piece of 170 x 170 stainless plate on top of the hole that was connected by a push rod so i could open and close the size of the exit port.

So over the last three days i have tried a ‘ lot’ of different combinations of air and exit port size and to be honest i was not getting the results i wanted or in fact as good as i was getting with the last Configuration
So this morning i took the top off and formed a rear exit that was the same size as the top box approx 90% top box csa and 90% exit.
Basically the flow is now straight through the top box and into the back of the barrel and then down...

This format has had a dramatic change!
Air is full open but it does run through 1.5 mt of 85mm pipe ... no smoke but slow to get vortex spinning, about 10 minutes into the burn the vortex is showing nicely and is not creeping forward at all!
The vortex continued spinning for one hour forty five minutes and never left the back or crept out of the after burner.

So a long smoke free burn.... however not surprisingly... not so hot on the hot plate !
Still this is exciting for me as i really like the long slow burn time and the hot plate was still acceptable temperature around 220c .
The ceramic glass is allowing a very even temperature across the hot plate regardless that the exit is at the far end.

Now i need to play with the exit size, first i will try 10% less then i will have to adjust the whole top box to get 100%

[Vortex]

That's great, I guess you saw my recent posts on Peters thread: donkey32.proboards.com/post/36099/thread

I've had 3 brilliant runs with the new configuration, majority of the burns sub 100ppm CO. Depressing in one way as I've spent the last 2 years and 200+ burns experimenting with different stumbler/port setups - only to discover now that it's better without them...

Even more annoying is I had 2 burns back when I first had the testo in 2019, that had long sub 100ppm CO. that both went down to 13ppm. I thought at the time the results were a mistake, but couldn't find anything wrong. I was experimenting with 2" of CF blanket on top of the afterburner roof. At that point I hadn't started making notes on each burn setup and saving them with the testo graphs, so later thought it must have been a lucky combination of insulation and ports, but had no record of what they were, so I missed the significance of it. Realise now it was the double layer of CF blanket on the afterburner roof creating the same long shallow top chamber with max surface friction to volume ratio.

As my stove has about 16 feet of 1 CSA channels in it, you wouldn't think an extra short bit above the afterburner would have that much effect, but it does. Tomorrow I'll arrange the top chamber so the floor and sides are the wrinkly vermiculite board, that'll further increase the surface area without making it any smaller.