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Dear Crispin,<br>
The pellets are 6mm dia. 1-2.5 cm long. The hole is 5cm in diameter.
I tried a few chips to block the hole. It usually took more than one
to stop it, and put out the fire. There isn't much evidence of the
fire mving up into the hopper. The attached picture shows the
position of grate in relation to the hopper. It is adjustable. A
mount of glowing charred pellets form in the bottom half of the
tube (6.2 cm ID pipe) out in front of the grate. This seems to be
self limiting, at least over the five hours it ran today.<br>
<br>
I ran it with a second hopper tube such that the air flowed outside
the inner 14cm diameter hopper (with lid) and inside the outer15.5cm
diameter hopper. The air has to pas through pellets in the cone
portion only.<br>
<br>
Shutting off the grate air does reduce the burn rate by as much as
half, but that is a guess and I am unsure if it works for hours.<br>
<br>
but wood pellets are cheating...<br>
<br>
next, a complete redesign for chips...<br>
<br>
courting failure....<br>
Alex<br>
<br>
<br>
On 18/01/2012 3:39 AM, Crispin Pemberton-Pigott wrote:
<blockquote cite="mid:03b401ccd5bc$ae0f7bc0$0a2e7340$@gmail.com"
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<p class="MsoPlainText"><span style="color:#1F497D">Dear Alex<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D">Hey that is
a good idea. The fire-under-hopper (FUH) is the approach
taken in the GTZ 7 stoves and I worried about the fact that
the fire would spread into the hopper if it bridged (which
it did). But the main issue for a more fire resistant set of
parts was the loss of power when that happened. The layout
is not exactly the same so I will consider it. The rest of
the number look OK. Having a predictable fuel is an
important part though. What was the length/diameter of the
fuel? What is the L:D ratio? What is the hole diameter? What
is the L:Hole diameter ratio?<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D">I’ll bet
there is a good chance the fire will choke and smoke then
recover if the bridge collapses.<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D">Retained
heat to keep the chimney working will be important if it
does.<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D">Thanks<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D">Crispin<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="color:#1F497D"><o:p> </o:p></span><br>
</p>
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