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.
kkp: Mercedes: Benches don't get real hot. In fact, they are rather cool compared to other areas. You shouldn't need a mix like you described
Jun 7, 2018 18:10:52 GMT -8
maartenmartens: beste Peter, ik heb je eergisteren een mail gestuurd via het contact formulier op je website , heb je die goed ontvangen ? mvg Maarten Martens, architect - geobioloog (mail betreffende de bouw van onze eigen RMH)
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Sept 18, 2018 4:48:00 GMT -8
daniel: in my experience as I am working now on something of that nature, I have thought of making a heat exchanger and distributing the heat through vents using a slower fan. Now after a few years I realize that mass heaters give out primarily radiant heat, for
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coastalrocketeer: Anyone posting in this shout box... if you have something you want people to see and respond to, create a thread in the appropriate forum section... this is not the place...
Dec 16, 2018 18:10:49 GMT -8
vesuvius: High Temperature Glass options,
Jan 4, 2019 16:28:17 GMT -8
vesuvius: Do any of you have experience with using the glass from home oven doors on a rocket stove? I'd like to have a viewing port on my stove but don't want to fork out for new ceramic glass. Any thought as to whether it would take the heat of a rocket stove?
Jan 4, 2019 16:30:40 GMT -8
yaya: you dont need the blowair for that temp..
Jan 13, 2019 16:43:57 GMT -8
flybywire: Glass window from an old washing machine is designed to take high temps. Cheap solution to your need.
Jan 27, 2019 0:10:58 GMT -8
coastalrocketeer: Anyone posting in this shout box... if you have something you want people to see and respond to, create a thread in the appropriate forum section... this is not the place to have a discussion... it is for short announcements
Feb 7, 2019 0:11:23 GMT -8
coastalrocketeer: you won’t likely get replies to questions here, and it is not a spot that makes holding an ongoing discussion possible...
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jlmtech: GADGET: CONSIDER USING A JET PUMP INSTEAD OF A BLOWER FAN TO INDUCE DRAFT; NO CLOGGING.
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