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Peter Jennen
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Thanks to everyone for all of the information.

I LOVE efficiency and when I stumbled on some youtube videos of these RMHs I was hooked! (Especially when Ernie took the top off their barrel and the riser was whistle clean!)

I plan on building my first heater next spring but want to throw an idea out there for all to consider.

Under optimum burning conditions, all fuel should be burnt before exiting the riser and going into the cooling barrel. Unburnt fuel is probably along the surface of the riser. So, I thought a metal ring around the inner edge at the top of the riser to super heat and kick the unburnt fuel from the edge into the center would help complete the burn. I later came across the old front disk brake rotors from my Ford E350 work van and viola! Kind of a catalityc converter for the RMH. A turbulant hot spot, if you will. I'll try to put in an image in this thread. I think this would be just the ticket, but what do I know?

PeterJ
 
Peter Jennen
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Here is the link to the photo: http://www.google.com/imgres?start=175&num=10&hl=en&safe=off&tbo=d&biw=1536&bih=729&tbm=isch&tbnid=Y0a-0G5P5INWWM:&imgrefurl=http://www.horsepowerfreaks.com/partdetails/EBC/Brakes/Brake_Rotors/High_Carbon_Blade/19264//Ford&docid=EvTfaiAwJhDKvM&imgurl=http://www.horsepowerfreaks.com/images/products/EBC/Brake_Rotors_High_Carbon_Blade_LRG.jpg&w=500&h=333&ei=O5O1UIaEGeeujALK44CoCQ&zoom=1&iact=hc&vpx=1221&vpy=294&dur=5047&hovh=183&hovw=275&tx=160&ty=98&sig=113254883483378908556&page=5&tbnh=144&tbnw=216&ndsp=46&ved=1t:429,r:1,s:200,i:7

This would lay over the riser chimney brick and the exhaust would vent out both the top and between the center disk vents to radially disperse the exhaust into the barrel.

I should add: I suspect most of the ash that accumulates up here is done at start-up from paper.

PeterJ
 
allen lumley
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Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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peter : disclaimer, i dont make a penny off of this, just so we start off on the same page, and both have a common place to look back to, please go to www.rocketstoves.com and order Ianto Evans great book 'rocket mass heaters' downloadable $15.00u.s. (make all the copies you want ) or paperback $18.00u.s. ! You will have the single best resource you can get, nowhere is there more information on Rocket stoves put in print than his book !

Again just to make sure I understand the location where you are suggesting its application, you want to place in in the stream of hot gases exiting from the Heat Riser, and immediately below the underside of the top of the barrel !

Its interesting that you picked that one video with Ernie Wisner to comment on ! At the very least,you will have a test bed with easy access to the subject you will be testing.

The Fire Science of this area of the rocket stove, as it is generally accepted to work is the hot gases leave the Heat Riser , Slam into the underside of your 55 gal drum,and churn as they spill over into a Doughnut-shape. This is usually considered the last place any final burning of pyrolysed wood gases, as its generally believed that the reason that the 55 gal. drum has held-up to 15 + years of use is that at this point the oxygen has combined with the hotter exhaust gases and the barrel can not burn in an oxygen deprived environment. wheuu - I can't really say that simpler ! - in fact it gets harder here !!!

SO -While there probably is room for improvement at this location, in order to have a rocket stove thats testable and that others can follow where you LEAD, (and verify your work), I would ere on the side of caution, and build as conventionally as possible, 1st out doors, - then indoor. After you have a working, clean burning Rocket stove of your own to play with - then you can use it for aTest Bed , modifying just one thing at a time !

If you wanted to go that route you can go to a brake/muffler shop , where they replace dozens of rotors a day. The general rule is there is usually a 3rd party that goes around and pays a flat rate regardless of size for old funkyy rotors. The Shop should be willing to swap out any one set of rotors for any other rotors, as they won't lose anything dealing with you that way, be aware that the rotors are cast steel and even though they are made for hi heat they can fail explosively.

One last thought on rotors if you find something useful, there are also hi temp ceramic rotors out there that can take temps that would melt steel !

* * * This is also a great place to score oil drums ! * * * Pyro - maticly - Allen L.

 
Peter Jennen
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Thanks for the response Allen.

The book is on my Christmas list.

My location will be outside for testing and then in an old barn that I keep my work truck in.

I don't suspect that the underside of the barrel top can obtain the temperature needed to burn all of the carbon,
hence the thought for the "catalityc converter" at the hottest point to
aggitate the gases and complete the burn. With the brake rotor not being exposed to any cooling surface,
the highest tempurature should be obtainable.

I also plan to include an exhaust fan in my system to ensure there will be no CO gases.

Hopefully this theory will be backed by good science.

PeterJ



 
allen lumley
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- I sometimes get so for ahead of myself due to my slow typing skills that I loose my point, which is that the toroid shape formed by the gases as they form around the outside of the Heat Riser and the top and sides of the 55 gallon
barrel is believed to be "just about prefect the way that it is"!

If you want to take-on the challenge of making any improvement in this area you will have to be incredibly methodic, and document every step of your progress moving from the known to the unknown, otherwise the 'True Believers'
will attack you for everything, including your syntax, and grammar and spelling!

I for one will offer my unlimited support to your project - as long as you don't mind my more conservative bent.

There being a few more Rocket Mass Heaters in my future I await any improvements you might find out there !

When you build your 1st rocket stove, and hear that roar the 1st time you will re-think your idea for a booster fan for your Rocket, but keep a fan on hand to place inside the last cleanout 'Tee".
With the cap then replaced, you can then use it to increase the draft when the wind is from the wrong direction, you need to clean out your wood ashes - but you really really need this one more 'burn',
or you've been away and your space is really cold and you need to save what you can, or all of the above !

We need more people like you to grow and prosper, just don't be in a hurry to be labeled a Heretic, they are considered a balanced meal all by themselves ! -for the good of the CRAFTs , - Pyro Allen L.
 
Peter Jennen
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LOL Allen! "If you want to take-on the challenge of making any improvement in this area you will have to be incredibly methodic, and document every step of your progress moving from the known to the unknown, otherwise the 'True Believers'
will attack you for everything, including your syntax, and grammar and spelling!" I've been there, received that, on motorcycle forums!

(What I do know is that fuel does not burn from spark or flame, it burns from heat and O2. Any surface that is below the "burn point" will inhibit a complete burn.
My objective is to get the unburned fuel (CO) to pass through the torent of fire.)

EDIT What I do know is that fuel needs heat and O2 to burn. Any surface that is below the "burn point" will inhibit a complete burn.
My objective is to get the unburned fuel (CO) to pass through the heat of the torent of fire or run into the "catalytic converter".

I've heard that rocket blast! I know what you are talking about. The draft fan is to ensure the dog and cat don't get CO'd out when the wind is from the east. It will be semi-automatic.

Peterj





 
allen lumley
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Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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peter J : a little history, the original Rockets were made w/ a dead soft building brick, that is insulative but non wear resistant and would fail by spauling or crumbling - not fracturing . the deep red common building brick is less insulative, fails by fracturing and while unsatisfactory any where in the system including the Heat riser, is/was used because they were free/cheap and available and many did not understand the difference ! When these systems were fired it took differing times, especially when compared to the more insulative soft brick, to come up to a smokeless steady state, the best will stabilize in under ten minutes. At that time we Are very close to max efficiency . The heat riser was replaced with a popular stove pipe sandwich with vermiculite or perlite in the center section - no additional brick laying needed. We had an improvement in reaching the smokeless steady state , mostly by seconds in the best builds but with great improvements in the marginal builds. Because of the high temperatures run, the inner stove pipe was oxidized in differing amounts, at differing rates, the innermost stovepipe was replaced with heavier gage steel. Here a lose of performance was found mostly in the marginal builds that took increased time to reach steady state, it was around this time that the longevity of the barrels 1st became noted, along with observations that the outer stove pipe of the heat riser had held up much better with most wear/damage at the top, It was at this time that speculation was made that ether the oxygen was combining with the hotter wood gases by preference, or an low oxygen state was being reached, with some original 55 gal barrels in use for 20 years, and no failures reported, the belief in low oxygen states is common. It needs more research because if that is true there has to be some CO production. Recently, and ill give you a link anon- A ridged refractory rock wool kaolin blend has been tested and examination after firing shows a surface that has been described as visually felt like , meaning an incredibly high surface area on an non conductive surface. It appears that the wood gases and air are now surrounded in a secondary combustion zone with Greatly increased surface area that glows red hot ! the time to a smokeless steady state is reported to be in seconds. This most be duplicated again and again with this, and separate and succeeding 'Rocket' builds, Also important is checking on the longevity of this new material - will the high surface area to volume ratio stay intact or will the affect of hot gases glaze it over ?

Due mostly to the areas in which improvements have been found,* ( and in the case of a thicker steel inner wall Heat Riser ) and conversely lost, it would appear that reducing heat sinks in the combustion zone rather than increasing them would bare the most fruit . Y.M.M.V.

Sorry the best I can do, go to www.permies.com/t/188711/podcast/Podcast-Rocket-Mass -Heater-Workshop - best I can do ! - G'luck ! - PYRO - AL

*also telling is the observation that marginal systems get the most improvement ! you've proven you've got the heart for this, go out and knock them dead, I want to say i knew you when !


 
Peter Jennen
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Allen,

Thanks again for all of the effort you have put into this thread.

PeterJ

 
Peter Jennen
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I found the Podcast!

 
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