<html><head></head><body text="#000000" bgcolor="#FFFFFF" data-blackberry-caret-color="#00a8df" style="background-color: rgb(255, 255, 255); line-height: initial;"><div style="width: 100%; font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">Heat transfer efficiency for charcoal is 45%+. </div><div style="width: 100%; font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">Crispin</div> <div style="width: 100%; font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);"><br style="display:initial"></div> <div style="font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);">>>Q10>>></div> <table width="100%" style="background-color:white;border-spacing:0px;"> <tbody><tr><td colspan="2" style="font-size: initial; text-align: initial; background-color: rgb(255, 255, 255);"> <div id="_persistentHeader" style="border-style: solid none none; border-top-color: rgb(181, 196, 223); border-top-width: 1pt; padding: 3pt 0in 0in; font-family: Tahoma, 'BB Alpha Sans', 'Slate Pro'; font-size: 10pt;"> <div><b>From: </b>Paul Anderson</div><div><b>Sent: </b>Monday, September 16, 2013 07:25</div><div><b>To: </b>Discussion of biomass cooking stoves; James S. Schoner</div><div><b>Reply To: </b>Discussion of biomass cooking stoves</div><div><b>Subject: </b>[Stoves] Amount of charcoal for simmering</div></div></td></tr></tbody></table><div style="border-style: solid none none; border-top-color: rgb(186, 188, 209); border-top-width: 1pt; font-size: initial; text-align: initial; background-color: rgb(255, 255, 255);"></div><br><div id="_originalContent" style="background-color: rgb(255, 255, 255);">
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Stovers, (this will also be a "post" at my <a class="moz-txt-link-abbreviated" href="http://www.drtlud.com">www.drtlud.com</a>
website, BUT all replies and discussions should be directed via the
Stoves Listserv. Dr TLUD does NOT carry on separate discussions
via comments to his website.)<br>
<br>
I am looking for a calculated answer that could give guidelines
about the sizes of charcoal-burning stoves, referring to how much
charcoal must be consumed for the cooking tasks.<br>
<br>
Question: How much charcoal is needed (per minute, or per hour,
or ??) to maintain a pot (5 liters?) of already-boiling water at the
simmer temperature of about 96 deg C?<br>
<br>
So many variables, but the replies can state whatever "givens" or
assumptions you wish to make, such as:<br>
<br>
1. Heat transfer efficiency of the stove-pot configuration: Is
30% about typical? And does that vary between clay-mud charcoal
stoves vs metal charcoal stoves? Please specify, if your response
takes that into account.<br>
<br>
Reference: See <a class="pseudolink" href="http://search.mywebsearch.com/mywebsearch/redirect.jhtml?searchfor=heat+transfer+efficiency+charcoal+stoves&cb=XQ&p2=%5EXQ%5Exdm002%5ES03729%5Eus&qid=499b92ca6697461da7047b820086bd7d&n=77DE8857&ptb=F7EBB78D-F7A7-4077-B858-0D10F0C7CB0E&si=COjP4cCp0rMCFao7MgodRQUALQ&pg=GGmain&action=pick&ss=sub&pn=1&st=hp&qs=&pr=GG&tpr=hpsb&redirect=mPWsrdz9heamc8iHEhldEVRIIbml7k2%2FvmB8U5crkZmbOTdLROAzdl%2F4ZQYYskvUwjkty6%2BVZ%2BNQiIr863cMN8jdRHpxuJvwsN2u6HPpdnPNB%2BBymTTjJMbwcgCi5H8Q&ord=1&ct=AR&" target="_blank">Experimental study for improving energy <b>efficiency</b>
of <b>charcoal stove</b> </a> <br>
<a class="moz-txt-link-freetext" href="http://nopr.niscair.res.in/bitstream/123456789/3794/1/JSIR%2068(5)%20412-416.pdf">http://nopr.niscair.res.in/bitstream/123456789/3794/1/JSIR%2068(5)%20412-416.pdf</a><br>
with reported efficiencies between 21% and 62%.<br>
<br>
2. Still air, no wind.<br>
<br>
3. Comments on types of pots (Stainless vs aluminum vs other).<br>
<br>
4. Lid or no lid. Probably no lid because so much testing is done
with no lid on pot.<br>
<br>
5. Ambient temperature: probably 22 to 27 deg C.<br>
<br>
6. Any other variables.?<br>
<br>
Comments: The question arises because the TLUD stoves (and any
other charcoal producing stoves) can be a convenient and low cost
source of charcoal for a household. That household has some
cooking needs for LOW heat (simmer-type), and a charcoal-burning
stove.<br>
<br>
Example from the world of stove testing: a pot with 5 liters
brought to boil can be placed onto a charcoal stove for the
remaining 45 minutes of the standard water boiling test (WBT). The
charcoal could be already red-hot, having been placed in the
charcoal stove directly from the TLUD stove that made the
charcoal. How much charcoal is needed for that simmering task?<br>
<br>
When we know the amount of charcoal, we can calculate backwards to
determine how much raw fuel was needed to make that charcoal.
(That amount of raw fuel is approximately 5 X of the charcoal
weight.) Example: 100 g of char is produced from 500 g of woody
biomass. <br>
<br>
Therefore, about 70% of the energy content of the raw fuel would be
available for INITIALLY putting heat into the pot. I think we
should assume better than 40% heat transfer efficiency because that
is the target for Tier 4 stoves and can be achieved by gas-burning
stoves. 40% of 70% is 28%, so round it to 30%. And 30% of the
energy content of the raw fuel is how much? 1 kg of wood has 16
MJ, so 500 g has 8 MJ, and 30% would be 2.4 MJ. <br>
<br>
Somebody please complete the calculations: <br>
<br>
A. 2.4 MJ will raise 5 liters (5000 g or ml) of water how many
degrees?<br>
<br>
B. How many g or ml of water can be brought to 100 C if
starting temp of water is 20 C?<br>
<br>
In the end, I hope we have some understanding about the amount of
raw fuel and resultant charcoal needed to accomplish the WBT with
minimal waste.<br>
<br>
Paul<br>
<pre class="moz-signature" cols="72">--
Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: <a class="moz-txt-link-abbreviated" href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</a>
Skype: paultlud Phone: +1-309-452-7072
Website: <a class="moz-txt-link-abbreviated" href="http://www.drtlud.com">www.drtlud.com</a></pre>
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