<div dir="ltr"><div>Paul: <br><br>@ Philip's calculations: I am not used to kJ calculations, so this is how I understand: (100-15) refers to raising the water temperature from 15C to 100C and 4.186 is the conversion factor kJ/kCal. Wood LHVs are contextual and I imagine so too charcoal LHV, depending on the input and operating conditions. am not sure about his Case 2; a little confusing. <br></div><div><br>Anyway, Philip is introducing the concept of "system efficiency". This is radically different from "stove efficiency" whose computations there seem to be allocating different inputs to different outputs. <br><br>And you wrote of "FUEL efficiency measured by communities, not by single stoves."<br><br>Together, you two seem to suggest that whatever the lab tests and ISO TC 285 ratings, project design must be informed by appropriate contexts of fuel availability and relative costs, and a collective measure of "before" and "after" service requirements and community-level performance. <br><br>I may add that "communities" also include users of wood and charcoal other than household stoves. <br><br>It is ridiculous under CDM rules to have to destroy "old" cookstoves, or under Kirk Smith's rule to not permit "stacking". Projects with large enough % of users in a particular context, finding new cookstoves acceptable, cleaner, and usable enough to do many or most of the tasks from "old" cookstoves, are likely to yield measurable benefits promised. (Except climate benefits and aDALYs which are fictional.) <br><br>Boiling water for coffee this morning as the weather is turning cooler around here, I realized that even boiling water is a multi-purpose activity, the steam warming up the kitchen. A cookstove will often be used for multiple products and "single stove" efficiency ratings for just boiling water have no practical counterpart. Or meaningful application. <br><br>But we are on to the search for savior stoves. Let's pray. <br><br>Nikhil<br><br clear="all"><div class="gmail_extra"><div><div class="gmail-m_2269950885845606436m_-7584573652884598908m_7698246671613159871gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><font face="georgia, serif">------------------------------<wbr>------------------------------<wbr>------------<br>Nikhil Desai</font></div><div><span style="font-family:georgia,serif;font-size:small">(US <a href="tel:(202)%20568-5831" target="_blank" value="+12025685831">+1) 202 568 5831</a></span><font face="georgia, serif"><br><i>Skype: nikhildesai888</i><br></font><br></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div>
<br><div class="gmail_quote">On Mon, Sep 25, 2017 at 8:41 AM, Paul Anderson <span dir="ltr"><<a href="mailto:psanders@ilstu.edu" target="_blank">psanders@ilstu.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid">
<div bgcolor="#FFFFFF">
Philip<br>
<br>
I suspect something is not correct,<br>
<br>
1. In your example, the 0.395 kg wood contains 5930 kJ of total
energy.<br>
2. You calculate that the char produced would contain3163 kJ.
That would be 53.3% of the total energy is maintained in the char. <br>
3. Later you write that "the efficiency of char production would
have been ... 36.4%. <br>
<br>
I leave it for you and others check this out.<br>
<br>
3. At the end you say
<span><blockquote type="cite"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">this
would have been statistically indistinguishable from the
efficiency with no char production – i.e. it would have shown no
benefit to char production. </span></blockquote></span>
That statement could also be written "it would have shown no benefit
to cooking the regular, full-combustion way, without char
production." <br></div></blockquote><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid"><div bgcolor="#FFFFFF">
And since produced char can be stored for later use, is essentially
smokeless cooking for ventilated "indoor" cooking, and can be used
for other purposes, cooking with char-producing stoves could be
viewed as having some benefits.<br>
<br>
I respect those of you who are good number crunchers and know the
formulae. Please comment on the above. I am here to learn.<span><br>
<br>
Paul<br>
<br>
<br>
<pre class="gmail-m_2269950885845606436m_-7584573652884598908m_7698246671613159871m_4632430931129843934moz-signature" cols="72">Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: <a class="gmail-m_2269950885845606436m_-7584573652884598908m_7698246671613159871m_4632430931129843934moz-txt-link-abbreviated" href="mailto:psanders@ilstu.edu" target="_blank">psanders@ilstu.edu</a>
Skype: paultlud Phone: <a href="tel:(309)%20452-7072" target="_blank" value="+13094527072">+1-309-452-7072</a>
Website: <a class="gmail-m_2269950885845606436m_-7584573652884598908m_7698246671613159871m_4632430931129843934moz-txt-link-abbreviated" href="http://www.drtlud.com" target="_blank">www.drtlud.com</a></pre>
</span><div><div class="gmail-m_2269950885845606436m_-7584573652884598908m_7698246671613159871h5"><div class="gmail-m_2269950885845606436m_-7584573652884598908m_7698246671613159871m_4632430931129843934moz-cite-prefix">On 9/25/2017 4:29 AM, Philip Lloyd
wrote:<br>
</div>
<blockquote type="cite">
<div class="gmail-m_2269950885845606436m_-7584573652884598908m_7698246671613159871m_4632430931129843934WordSection1">
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">I
carried out a thought experiment.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">In
case 1, a cookstove burning wood boiled 5 litres of water at
an energy efficiency of 30%. The useful energy provided was
5*4.186*(100-15) = 1779kJ. This required
5*4.186*(100-15)/0.3 = 5930kJ. If the as-fired wood had a
LHV of 15MJ/kg, it would have needed 5930/15000 = 0.395kg
wood<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">In
case 2, the same stove was operated to produce charcoal
while also boiling 5litres of water. More wood would be
needed, because not all the wood would be combusted – some
would be left as char. If you fed 0.395kg wood to be turned
into char at 29% efficiency, and the char had an LHV of
28MJ/kg, then the char would have an energy of
0.395*28000*0.29=3163kJ. The wood from which it was prepared
had an energy content of 5930kJ, which was what was needed
to boil the water in the absence of char production. So
5930-3163 = 2768kJ of additional energy* would be needed to
boil the water if there was char production. At 15MJ/kg,
this is 2768/15000 = 0.185kg extra wood, or an increase of
47% in the wood supply. The total energy supplied would then
be 5930+2768 = 8698kJ. The energy efficiency of cooking
would therefore fall to 1779/8698*100 = 20.5%, while the
efficiency of char production would have been 3163/8698*100
= 36.4%. The system efficiency would have been 20.5+36.4 =
56.9%<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">If
you used the WBT formula, the efficiency of boiling with
char production would have been 1779/(8968-3163)*100 =
32.1%. Given the measurement errors inherent in the WBT
method, this would have been statistically indistinguishable
from the efficiency with no char production – i.e. it would
have shown no benefit to char production. <u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">Prof
Philip Lloyd<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">Energy
Institute, CPUT<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">PO
Box 1906<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">Bellville
7535<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">Tel
021 959 4323<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">Cell
083 441 5247<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">PA
Nadia 021 959 4330<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt">*This
assumes that there is no endotherm in the pyrolysis of wood
in the presence of air, and that all the pyrolysis products
except the char burn to provide heat. There is evidence in
the literature of no endotherm in the presence of air.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(31,73,125);font-family:"Calibri","sans-serif";font-size:11pt"><u></u> <u></u></span></p>
<div>
<div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(181,196,223) currentColor currentColor;padding:3pt 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US" style="color:windowtext;font-family:"Tahoma","sans-serif";font-size:10pt">From:</span></b><span lang="EN-US" style="color:windowtext;font-family:"Tahoma","sans-serif";font-size:10pt"> Stoves
[<a class="gmail-m_2269950885845606436m_-7584573652884598908m_7698246671613159871m_4632430931129843934moz-txt-link-freetext" href="mailto:stoves-bounces@lists.bioenergylists.org" target="_blank">mailto:stoves-bounces@lists.b<wbr>ioenergylists.org</a>] <b>On
Behalf Of </b>Paul Anderson<br>
<b>Sent:</b> Sunday, September 24, 2017 11:27 PM<br>
<b>To:</b> Discussion of biomass cooking stoves<br>
<b>Cc:</b> <a class="gmail-m_2269950885845606436m_-7584573652884598908m_7698246671613159871m_4632430931129843934moz-txt-link-abbreviated" href="mailto:ndesai@alum.mit.edu" target="_blank">ndesai@alum.mit.edu</a>; Andrew Heggie; Crispin
Pemberton-Pigott<br>
<b>Subject:</b> Re: [Stoves] stoves and credits again<u></u><u></u></span></p>
</div>
</div>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Philip, Tom and all,<br>
<br>
Philip is mostly correct. Actually wood takes up (has) too
much WEIGHT. Wood has 3 times (or more, if the char is poorly
made) the ENERGY value of charcoal that could come from that
char. But it has about 5 times the DRY weight of the char,
plus there can be 20 to 50% moisture content to make the wood
even heavier. <br>
<br>
And the charcoal has almost double (30 vs. 16) the energy
content by weight, but char is so much lighter per unit of
volume. So the trucks are buldging upward and sideways with
the sacks of charcoal strapped to them. Weight of charcoal is
not a problem for most transport.<br>
<br>
Apart from the transportation issue, I believe that the appeal
of charcoal is that it does not smoke (not much). CO is
invisible and deadly, but the people learn to cook on the
balcony or keep some air flowing. And it does not turn the
bottom of the pots black.<br>
<br>
Charcoal is an attractive fuel. Too bad it is made by
processes that throw away 2/3rds of the energy. (So, let's
promote TLUD stroves and collect the char for sale to the
urban folks. Only one third of the cutting of wood/forest.) <br>
<br>
So, if 100,000 households (mainly in rural or peri-urban
areas) would use TLUDs, the resultant char would equal to the
energy needed for an approximately equal number of households
(mainly urban) that would want to burn charcoal. <br>
<br>
Now that would be FUEL efficiency measured by communities, not
by single stoves.<br>
<br>
Paul<br>
<br>
<br>
<u></u><u></u></p>
<pre>Doc / Dr TLUD / Prof. Paul S. Anderson, PhD<u></u><u></u></pre>
<pre>Email: <a href="mailto:psanders@ilstu.edu" target="_blank">psanders@ilstu.edu</a><u></u><u></u></pre>
<pre>Skype: paultlud Phone: <a href="tel:(309)%20452-7072" target="_blank" value="+13094527072">+1-309-452-7072</a><u></u><u></u></pre>
<pre>Website: <a href="http://www.drtlud.com" target="_blank">www.drtlud.com</a> <u></u><u></u><br> </pre></div></blockquote></div></div></div><br>
<br>
<br></blockquote></div><br></div></div></div>