Post by palmalyckan on Feb 13, 2017 2:33:36 GMT -8
Hey All I am a fan of rockets and have been reading on this forum for years.
I am a new member and soons its time for a BBRMH build inside the house which I am building. I read in many places that the temp of gases in the riser can reach over 1000C but I cant find many testresults from folks who who are measuring these temperatures. Searched the permies and this forum and its the same numbers being repeated, where is the source.
Hi Palmalyckan, welcome to the boards. The source of this temperature numbers is probably me. In 2012, during the development of what we know now as the batchrocket I used a digital thermometer and K-type thermocouplers. Those couplers are good up to 1000º C, and I destroyed two of those inside the riser. Luckily, I was able to borrow a better one from a guy in France, that's how I found out the flame temperatures in the riser can routinely be over 1100º C, almost every test run.
Top temperature I measured this way was as high as 1173º C, very close to the so-called physical maximum of 1200º C. Also, I found out the highest temp in the riser shifts up during the top of the burn and shifts down again when the glowing phase is imminent. I'll look around when exactly I wrote about the mentioned temps, it's on this forum I'm sure.
The document you are linking to is a report of experiments done on a small rocket cook stove and as such isn't comparable to a proper batchrocket.
Personally, I never said metal would melt inside a riser. It's all about corrosion, in an oxygen-rich and carbon frugal environment coupled to high temperatures. Under these circumstances every burn the metal will deform and show heavy spalling, i.e. flakes of dull grey, non-conductive and surprisingly lightweight metal fall off.
Hi, Measuring temperatures is a complicated thing. In the flame of a candle, temperatures can go between 1200 and 1400°C : not everywhere in the flame but in specific places where the combustion is complete. The problem in the case of the candle is that the instrument used to measure (the tip of the probe) is big compared to the power of the flame and can affect the measuring by cooling the place you try to measure. Another problem is that there are different zones in the flame which have not the same temperature, then those highest temperatures zones must be known to find those high temperatures. In a rather big flame (produced by a rather big rocket stove, for example), it seems to be easiest to measure high temperatures -especially after some time, when the riser is very hot and doesn't cool the measuring zone. But there is another problem : the excess of air. In a candle flame zone where the combustion is complete and the temperature very high, there is not much excess of air which would, otherwise, cool the zone. In a standard rocket, there is often a lot of excess of air which "dilutes" the high temperatures. In the contrary, in the batchbox stove, the excess of air is low and there is very few cooling metal parts, then temperature go higher.
Last Edit: Oct 15, 2017 8:03:25 GMT -8 by pyrophile
we can see the temperature on top of the barrel on a full blast:
did anyone managed to get into the orange range?
I've had the entire barrel of one of my stoves up to "medium cherry." I burned the stove continually for approximately 12 hours before I stuffed it full of small Osage Orange fence posts. The posts had been "seasoned" for over 60 years!
The 7-inch Batch Box with S-Portal was over-fueled and smoking so I suspect the flame was exiting the heat riser and burning within the barrel. I had to run around the shop with water to keep things from lighting on fire!
EDIT: The temperature of the barrel will always be lower than the temperature inside the heat riser, though; the larger volume and surface area within the barrel combined with a heat-shedding environment (outside is cooler than inside) means that flame temperature can only be inferred using barrel temp.
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deadstarsstillburn: Hi there. I was directed this way by folks on the Permies.com website and am hoping I can get some information on how a total newbie can get started designing, siting, building, and not-dying-in-a-horrible-house-fire with a new RMH in a 160-year old home
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deadstarsstillburn: The people over there recommended either a 6" batchbox or an 8" J-tube. I don't know what those are but am going to try to figure that out. What I need is a blueprint that I can scale to fit the need for my house. I have something likne 5000 square feet
Oct 21, 2020 6:53:00 GMT -8
deadstarsstillburn: but I do not need to heat all of it by any means. probably only need to heat half of that, maybe less.
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deadstarsstillburn: moreover, the house has 3 storeys (large attic) so I assume if I get very efficient heating on the ground floor, that will go a long way toward heating the upstairs as well, no?
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