<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On 24/01/2008, at 6:21 PM, evan battaglia wrote:</div><br><blockquote type="cite">I met a guy on the AT who brought two pop can alcohol stoves: one for boiling and one for simmering. The simmering one had less holes I believe and thus put out less heat. He said the "simmer rings" for other alcohol stoves don't really work so at 0.2 oz or whatever a coke can stove weighs, why not bring another one.</blockquote><br></div><div>Ah, at last a question that I can claim some experience on.</div><div><br class="webkit-block-placeholder"></div><div>My daughter did a science project on efficiency of coke can alcohol stoves. We made up eight with different numbers of holes and somehow it became my task to boil 380 cups of water, one at a time, with stopwatch and thermometer. What we found was that the number of holes above eight made very little difference (we had 8, 16, 24 and 32). Fewer or smaller holes used less fuel, but not by much. The most important factor, in a can stove with no adjustable vents, was the distance from stove to pot. The closer you put the stove the longer and slower the burn. With a 1 cm gap (0.4 inches) we could boil 250 ml (1 cup) of water for 19 minutes. Increasing the gap brought the water to the boil faster but wasted fuel and reduced the boiling time to 6 minutes at 5 cm (2 inches). At that distance we were getting an inefficient orange flame and a sooty pot at the end. All tests were performed inside so crosswinds were not a problem.</div><div><br class="webkit-block-placeholder"></div><div>Below is a clip from our results. The table below may not look straight in your mail program. 5 cm -> 5 mins 53 secs, 1 cm -> 19 mins 18 secs</div><div><br class="webkit-block-placeholder"></div><div>
<table border="0" cellpadding="0" cellspacing="0" width="194" style="border-collapse: collapse; position: static; z-index: auto; ">
<col width="194" style="mso-width-source:userset;mso-width-alt:7094">
<tbody><tr height="48">
<!--StartFragment-->
<td height="48" class="xl24" width="194">All test groups for a given distance have
been averaged to reduce comparisons to a single variable, the distance
between pot and stove.</td>
<!--EndFragment-->
</tr>
</tbody></table><br>
<table border="0" cellpadding="0" cellspacing="0" width="176" style="border-collapse: collapse; position: static; z-index: auto; ">
<!--StartFragment-->
<col width="44" span="4" style="mso-width-source:userset;mso-width-alt:1609">
<tbody><tr height="13">
<td height="13" class="xl24" width="44">5 cm</td>
<td class="xl24" width="44">3.5 cm</td>
<td class="xl24" width="44">2 cm</td>
<td class="xl24" width="44">1 cm</td>
</tr>
<tr height="13">
<td height="13" class="xl25" align="right" x:num="0.00409027777777778">05:53</td>
<td class="xl26" align="right" x:num="0.00493171296296296">07:06</td>
<td class="xl26" align="right" x:num="0.00748090277777778">10:46</td>
<td class="xl26" align="right" x:num="0.0134021990740741">19:18</td>
</tr>
<!--EndFragment-->
</tbody></table><br>
</div><div>Here are the results for number of holes -> minutes</div><div><br class="webkit-block-placeholder"></div><div>
<table border="0" cellpadding="0" cellspacing="0" width="194" style="border-collapse:
collapse">
<col width="194" style="mso-width-source:userset;mso-width-alt:7094">
<tbody><tr height="48">
<!--StartFragment-->
<td height="48" class="xl24" width="194">All test groups for a given distance have
been averaged to reduce comparisons to a single variable, the number of holes
in stove.</td>
<!--EndFragment-->
</tr>
</tbody></table><br>
</div><div>
<table border="0" cellpadding="0" cellspacing="0" width="176" style="border-collapse:
collapse">
<!--StartFragment-->
<col width="44" span="4" style="mso-width-source:userset;mso-width-alt:1609">
<tbody><tr height="13">
<td height="13" class="xl24" width="44">8 holes</td>
<td class="xl24" width="44">16 holes</td>
<td class="xl24" width="44">24 holes</td>
<td class="xl24" width="44">32 holes</td>
</tr>
<tr height="13">
<td height="13" class="xl25" align="right" x:num="0.00703935185185185">10:08</td>
<td class="xl26" align="right" x:num="0.005359375">07:43</td>
<td class="xl26" align="right" x:num="0.00529918981481481">07:38</td>
<td class="xl27" align="right" x:num="0.00510011574074074">07:21</td>
</tr>
<!--EndFragment-->
</tbody></table><br></div><div><I had some photos here but my mail didn't appear on the list so I guess there's some sort of filter to prevent overload. You'll have to imagine my stove test rig></div><br><div apple-content-edited="true"> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="color: rgb(31, 73, 125); font-family: Arial; font-size: 12px; font-weight: bold; ">Denis Stanton</span></div><div><span class="Apple-style-span" style="font-size: 13px; "><div><font class="Apple-style-span" color="#808080" face="Arial" size="2"><span class="Apple-style-span" style="font-size: 10px; "><a href="mailto:denisstanton@mac.com">denisstanton@mac.com</a></span></font></div></span></div></div></span> </div><br></body></html>