|
|
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. www.bioenergylists.org/stovesdoc/Ogle/DOStovetest.html is one but its a small 5", And there is a lot of talk about metal melting and burning through, but burning through has a lot to do with oxidization and not just high temps. Do you know of more results where the temps a measured, documented over 1000C? Greetings from South of Sweden Pontus Af Palmalyckan |
|
|
|
Post by peterberg on Feb 13, 2017 3:19:43 GMT -8
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.
|
|
|
|
Post by palmalyckan on Feb 13, 2017 11:42:02 GMT -8
Thank you Peterberg.
Yes, small rocket stove is not in the same caliber as the batch rocket, yet it did produce quite some heat with only sticks. It was the only thing I could find on the net about the 1000C.
And now I am glad to have found a reliable source, so it was not a made up number because some metal melted away. its actually measured.
|
|
|
|
Post by Orange on Oct 14, 2017 11:42:29 GMT -8
there was a video on YT "A very hot little stove 938 °C (1720.4 °F)" by Apostol:  so if this small uninsulated rocket can reach 938C, than any insulated rocket goes easily over 1000C. I'd like to see more evidence  |
|
|
|
Post by pyrophile on Oct 15, 2017 7:51:51 GMT -8
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.
Benoit
|
|
|
|
Post by Orange on Nov 1, 2017 1:11:42 GMT -8
|
|
|
|
Post by pinhead on Nov 1, 2017 6:04:35 GMT -8
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. |
|
|
|
Post by Orange on Nov 1, 2017 6:51:17 GMT -8
nice, that means it's probably well over 1000C inside, on the limit of breaking refractory  Do you have a pic? |
|
|
|
Post by pinhead on Nov 1, 2017 7:27:05 GMT -8
nice, that means it's probably well over 1000C inside, on the limit of breaking refractory Do you have a pic? No. Like I said, I was running around with water trying to keep the shop from burning down so I didn't have time to take a pic! It was painful even being in the same room as the thing! |
|
|
|
Post by Orange on Nov 1, 2017 13:18:14 GMT -8
|
|
|
|
Post by Jura on Nov 1, 2017 14:13:58 GMT -8
Wow! is that photo showing the barrel of your unit ? |
|
|
|
Post by Orange on Nov 2, 2017 1:09:09 GMT -8
 Wow! is that photo showing the barrel of your unit ? No, that's just illustration of pinhead's situation This one even reached lemon yellow. It has to be heel to have that indoors.
|
|
Do you have a pic?
