I am new to the site, but am an instant huge fan. Thank you all for everything that you do and share. I am excited to be a part of this community.
I came across your website through searching out rocket stove / thermal mass heater designs. I searched through the forum for this before posting the topic. I am trying to find which existing design can produce the hottest temperatures. Open to any design and any material needed in order to achieve the absolute highest temperature. Any thoughts?
I'm not an expert, but I saw on this video, [youtube]https://www.youtube.com/watch?v=0xTS3curk8I,[/youtube] the guy uses a fan to drive air into the heat chamber through about 8 small nozzles, and it gets it really hot and efficient there, rather than having a natural air intake. I suppose to get it really hot, you could try to make a tesla turbine: https://www.youtube.com/watch?v=j7DNKIsdBZc, to try and drive the air in. The air flow is not very rapid but it relies on the boundary layer effect of a smooth spinner instead of a fan spinning (it's actually several small washers housed in a sheath to make it smoother than have the washers exposed). But at high driven rpms, there is a drop in noise to a tuned sound.
Hi Jason; Welcome to Permies!
Well there is a big difference between a rocket stove (meant for cooking) and a rocket mass heater (meant for heating)
Which were you interested in?
With rocket mass heaters. Peter Bergs Batch box design would produce the hottest temperatures. Here is a link to his site http://batchrocket.eu/en/ Ceramic boards and ceramic fiber blanket in your core and riser, are quickly becoming the builders material's of choice.
These are proven technology for obtaining the most efficient hottest burns.
Many other methods have been tried. You-tube is very popular for folks to showcase their ideas and builds.
Not all of them last very long. Sometimes they fail ...We call them "Flaming units of death" only rarely do we hear about this. Most folks are too embarrassed and you never hear about their project again.
Check out the rocket mass heater forum here at Permies. Check out Peter Bergs site. And another site run by a good friend http://donkey32.proboards.com/ also full of great information.
Find a copy of The Rocket Mass Heater Builders Guide, its full of build information.
Come back with all your new questions after you check things out.
My 8" J tube , built old school with heavy firebrick can create an 8" glowing orange circle on the barrel top. Reads 1100F
That's pretty hot.
Mid riser temps on Batch box's run 1500-1800 F That's even hotter.
I don't think any run hotter than that.
My hi-bred j tube can get well over 600c on top of the barrel, but I think a full batch box can get quite a bit higher still!
posted 10 months ago
Thank you to everyone for responding. I really appreciate the sharing of knowledge as well as the links and leads. The reason for me posing this question is to experiment with any design that can potentially reach incinerating conditions which are 2,400 degrees fahrenheit. I am currently working with a gentlemen in India whom is trying to find an economical solution for burning plastic waste. We have found an environmental engineering company willing to test the exhaust of various items being burned in order to see what all types of waste can be burnt without leaving toxic pollutants.
I came across a video on youtube where Paul Wheaton is suggesting not to use steel in the core due to it having a melting point at 2,600 degrees fahrenheit. I am assuming that he has been able to produce a design that can achieve temperatures higher than the 2,600 since that is a concern of his. This is the type of design I am seeking. The cost will be very high for the environmental testing, so really we will only have one shot to get it right. The correct design will be everything, so whatever the system design needs to be and with whichever materials are needed.
All help is greatly appreciated!
posted 10 months ago
It does not sound like the type of stoves we make are very suitably for your proposed use, I don’t think many of us have suitable equipment to measure the hottest parts of a rocket stove anyway!
The centre of the heat riser near, the bottom, is where the most extreme temperatures are found but that part is pretty inaccessible and difficult for the average builder to measure. We tend to quote external temperatures.
However there are very knowledgeable members on this forum who may have ideas about up scaling the rocket stove principle?
posted 10 months ago
Perhaps I will get lucky. I don't necessarily need to measure the exact temperature. I mean if the design is melting steel then we know that it is reaching at least 2600 degrees F, which is higher than current incinerator temps.
The hottest designs of rocket core can get near the melting point of steel, but that is not the reason for avoiding it.
First, steel conducts heat away from the fire, cooling it. You need to use insulating refractory materials to get the hottest fire.
Second, the heat plus atmosphere in a rocket core will quickly corrode bare steel, and steel softens and bends far below its melting point.
For the temperatures you are talking about, you will need to buy industrial refractory material rated for at least 2700F or better. This is a standard product, but is expensive.
Another relevant consideration is that at above something like 2300F, nitrogen will burn and create NOx (nitrous oxide and other compounds), which are hazardous in themselves. I don't know how commercial incinerators avoid that issue, but I would investigate it before going much further. This paper has a lot of intimidating-looking math, but the first page gives significant basic information.