yasin
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Posts: 33
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Post by yasin on Feb 26, 2020 23:57:59 GMT -8
Hello all,
some news about the development of the Batchblock V2, based on the full primary air developments of our dear peterberg :
it's in french, but you can use the auto translation.
I was rather expecting 100 ppm in this phase of the burn, but I think that the port is too wide since my concrete slabs are only 4 cm thick.
Regards,
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Post by Karl L on Feb 27, 2020 11:55:09 GMT -8
Thanks Yasin, that is very interesting.
Where/how does the primary air enter the fire box?
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yasin
New Member
Posts: 33
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Post by yasin on Feb 27, 2020 22:20:38 GMT -8
Hello Kar, thank you, the air come from the aluminium pipe to a metal box underneath the firebox, then to the front of the firebox.
Regards,
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Post by Karl L on Feb 28, 2020 3:30:33 GMT -8
Thanks!
Another question: in the video I only see a small amount of wood - do you fill the fire box with wood at the start of the burn?
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yasin
New Member
Posts: 33
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Post by yasin on Feb 28, 2020 8:49:39 GMT -8
Hello all, First results with a full load of 15.8 kg of wood at 18% moisture. Lit from the bottom, close to the port. Cold start. The testing is done very close to the specifications of the EN15250. The draft is mecanically controlled to be between 12 and 14 Pa. Average results are very good : CO 548 ppm at 13,6% O2. There are some leaks in the heater since the outside layer is not complete. I think that the O2 values should be lowered by 2% at least. The efficiency isn't correct too - the values are much lower that what they should be.
But there is some spiky behavior
I think that it is due to the port being too large, so I'll test that tomorrow. Maybe there is a restriction in some place too..
Regards,
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yasin
New Member
Posts: 33
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Post by yasin on Feb 28, 2020 8:54:51 GMT -8
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Post by Karl L on Feb 29, 2020 10:48:55 GMT -8
Thanks, Yasin. Do you know what temperature the primary air must be heated to, in order to produce the clearn burn without secondary air?
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yasin
New Member
Posts: 33
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Post by yasin on Mar 6, 2020 10:25:55 GMT -8
Hello Karl, I can't measure the air temperature directly, but I think that now the temperature goes up to 250°C. Surely more preheating would be better. Regards,
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yasin
New Member
Posts: 33
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Post by yasin on Mar 13, 2020 8:20:24 GMT -8
Hello all,
I've been trying a lot of different configurations, and the things start to look better now !
Averages of the last burn : CO = 394 ppm and O2 = 16,5 %
Some pictures :
I still can't get the thing to be stable under 13,0 % of O2 (on a cold heater), but above that threshold the combustion is good. I tried 27 configurations up to now and nothing made the heater more stable. I even tried a cobra which worked awesomely on a hot heater, but very poorly on a cold start.
I think that there is a lack of oxygen in the heater in the most intense phase of the burn. When I added the cobra the flames where much brighter during the climax of the burn.. very impressive ! Nevertheless I still can't figure out a way to introduce more air in that part of the burn.
Regards,
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Post by Jura on Mar 13, 2020 11:48:40 GMT -8
Nevertheless I still can't figure out a way to introduce more air in that part of the burn. hmmmm... that would have probably complicated the build but how about introducing some more air by a slots in between bricks of firebox. Kinda Austrian Ecobox solution. Lets say inlet providing air would be adjustable by a damper/baffle. (BTW. would there be any native speaker and explain the difference in the meaning of those two last words above,please? ) I do realize the batchblock is a cross draft and the austrian is not, but ... Or maybe it has been tried before, and i'm spitting out a nonsense ?
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Post by Vortex on Mar 13, 2020 14:07:27 GMT -8
Hi Yasin, I haven't seen a sketchup of your new design, do you use an exit port on the riser/afterbuner/secondary burn chamber? I found that an exit port was key to the stability. If the fire ran out of air I made the exit port smaller.
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yasin
New Member
Posts: 33
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Post by yasin on Mar 14, 2020 7:57:02 GMT -8
Hello Jura , thanks for your advice ! I don't like the austrian system, too complicated and the bricks or refractory concrete air injectors are subject to very intense thermal stress ! Other mass heaters builder are taking this path but they use super expensive and stress-resistant injector bricks ( )
Vortex thanks for your advice too ! I wanted to try something like that next week with an vertical exit port.. you comfort me in that idea, buti tried a setup like that during the experiments of the batchblock V1 and it was a failure. I'll try it again !
Regards,
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Post by Vortex on Mar 14, 2020 11:40:06 GMT -8
You might be looking at the problem the wrong way around. Instead of to little air, maybe it is to much gas.
I think the exit port works by creating a maximum speed limit, which helps stop the core from running to fast - producing to much gas to quickly - which uses up all the air.
Noticed you are not using a threshold. Does your primary air blow on to the fire, that can increase the gas production.
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yasin
New Member
Posts: 33
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Post by yasin on Mar 14, 2020 12:41:55 GMT -8
Hi VortexThanks for your reply. I had not see the development of your core with the top port.. that is absolutely awesome ! Bravo ! I think i'll try something similar next week ! The air is fed from the door, upward and vertically. But anyway i think you are right. Regards,
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yasin
New Member
Posts: 33
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Post by yasin on Mar 15, 2020 4:00:29 GMT -8
This morning I tried a configuration similar to yours.
It was on a cold heater (8°C) with my normal testing setup. The draft is mechanically regulated to 12-14 Pa.
I burned 11 kg of Hornbeam with 500g of kindling wood. Top lit, right under the top port. I had closed the right-sided port that I normally use.
The firebox is 280x400x450 (WxHxD), so the section of the firebox parallel to the plan of the port (280x450) is very close to your heater (300x400 mm). I believe that this is the important dimension regarding the sizing of the port, so I made a port the same size as yours (50x175 mm).
The "afterburner" area is very close to your specifications : 230 mm wide by 110 mm high. This space is closed by a bended metal sheet.
Then a second port of 50x230 mm. Then a wide space 610 mm wide and 90 mm high.
After that the gases go down through two parallel downdraft channels.
The start was correct but after that it was smoking black smoke for at least an hour. The overfueling situation started under 16,0% O2.
I believe it is linked to the fact that the fire didn't go prudently from the top of the pile to the bottom. Burning coals went down in the pile and all the wood was burning at the same time. I don't know how to control such a situation with a top port.
Does this king of overfueling happens to your heater ?
Regards,
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