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<body class='hmmessage'><div dir='ltr'><div>Hi to all,</div><div><br></div><div><span style="font-size: 12pt;">In the ETHOS 2015 Dean Still's presentation he</span><span style="font-size: 12pt;"> states that:</span></div><div><span style="font-size: 12pt;"><br></span></div><div><span style="font-size: 12pt;">"</span><span style="font-size: 12pt;"><i>In a Rocket stove only forced air mixing results in almost complete
combustion. Strong jets of air are needed to fully mix the air, flame,
smoke, and gas.
Adding a chimney to a Rocket stove doesn’t result in the forceful jets
that create adequate mixing. Adding height to the Rocket combustion chamber, while giving more time for combustion to occur, also draws
in more cold air that results in more wood being burnt</i>."</span></div><div><span style="font-size: 12pt;"><br></span></div><div><span style="font-size: 12pt;">I was wondering if this "forced air mixing" should came from natural draft. For example, at some distance above the combustion zone, we can make some holes in the chimney allowing secondary air to enter and mix with the hot gases, creating a secondary combustion zone. Maybe we can put a "concentrator ring" above the holes like in a TLUD to create some turbulence.</span></div><div><span style="font-size: 12pt;"><br></span></div><div>This done, we can also increase the chimney height without the problem of "drawing more cold air that results in more wood being burnt", as part of the increased draft suction will be used to pull the secondary air inside the chimney.</div><div><br></div><div>With this tall chimney, hot gases can have more "mixing, time and temperature" to achieve the desired complete combustion.</div><div><br></div><div>Anyone tried something like this?</div><div><br></div><div>Some questions arising:</div><div><span style="font-size: 12pt;">- What distance above the primary burning zone should we put the secondary air?</span></div><div>- What number and size should be secondary air holes? (we can take experience from TLUDs)</div><div>- What size should be the concentrator ring? (we can take experience from TLUDs)</div><div>- What height should be the chimney after the concentrator ring?</div><div><br></div><div><br></div><div>Marc</div><div><span style="font-size: 12pt;"><br></span></div> </div></body>
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