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Crispin, Kirk and all,<br>
<br>
Subject Line changed to reflect the change in the Subject. This is
NOT about Kirk's stove, but about DATA about stoves being used for
stove selection.<br>
<br>
Crispin's message (below) raises TOO MANY questions about the
SPECIFICS OF stove test data. Instead, this message/topic is about
what is actually done when selecting stoves that would be put into
the market in a project. It is not about the household or cook
selecting a stove from the several choices in the market or project.
It is about project leaders and scientists examining stove
characteristics when making selections.<br>
<br>
My contention is that the numbers (data) do not matter all that
much. There are simply too many variables, so "perceptual
averages" (or generalities) come into the process. One example is
from (IMO = in my opinion) one of the best selection efforts that
use data, the large project in Indonesia. It created a 3-star
qualitative system to examine (I believe) 3 major characteristics
(like emissions, efficiency......). Really great implementation of
a rating system linked to financial assistance for stove purchases.
[[[ The much discussed Tier 0-to-4 system has not been used in a
similar way, as far as I know, even though there is a stove database
that gathers such data. ]]]<br>
<br>
But even with those stars, in the end the factors of cost and
attractiveness and convience of use and fuel issues can simply
overwhelm the "data" approach. <br>
<br>
So I say (mainly to Crispin, but to all), the three numbers for
fire-power can be used as indicators, if used at all. The "devil
in the details" (such as moisture content of the fuel, and including
or excluding time and fuel during ignition time, etc.) simply blow
away the data themselves. In other words, even with all of the
fullest calculations possible, words such as "6 kW firepower" simply
mean that this combustion arrangement "can really put out some
heat." From that generality, stove designers work with pot
placement, skirts, plancha vs direct flame to pot, size changes, etc
etc etc.<br>
<br>
For some readers (and project leaders, etc.), this message is
terrible because it diminishes the importance of data (and some
related employment and budgets). Others see it as "that's what I
do." Others say "so what? Not interested. Already have too much
invested in my stove and factory, so I ignore the data
evaluations." <br>
<br>
For stove INNOVATORS like Kirk Harris who are making experimental
units, getting test results are extremely important to fine-tune the
improvements so that we do (and should) pay attention to new
developments. <br>
<br>
But in the end, the data do not mean acceptance or rejection of a
manufactured line of stoves. Marketing overwhelms stove science.
So do cost and conveinece, etc.<br>
<br>
Paul<br>
<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>
<div class="moz-cite-prefix">On 6/9/2016 7:01 AM, Crispin
Pemberton-Pigott wrote:<br>
</div>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Dear
Kirk and Paul<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">There
were three numbers provided for power, the low the high and
the test-high.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">It
was mentioned that there was a scale under the stove (which
is a very good idea) and that readings were taken per 5
minutes (which is a pretty long interval).<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Was
the high power a maximum during the test phase, or the
average over the phase? If it was the average then it should
be presented like that because the phase includes an
ignition. If it is the maximum firepower, that would not be
the average including ignition.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">If
I say an electric stove has a 5 kW element, that is the
maximum input power. The cooking power is the input power
times the heat transfer efficiency. That is pretty
straightforward.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">So
I wondered if the scale readings were used to determine the
maximum power by using the burn rate, or if the power was
determined in some other way. If it was scale-based, it
means it is the average of the 5 minute intervals. If it was
based on the scale, what energy content was applied? Was it
the WBT sheet LHV (compensated for moisture? Was it the As
Received, Ash-Free heating value? Was that value
char-remaining-compensated to correct for the energy not
released? <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">The
determination of the firepower of a stove is not nearly as
easy as getting the cooking power, which in any case is what
people experience when they use it.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">At
the moment I do not have a clear picture of what that 6 kW
refers to, and as mentioned already, we don’t know the
cooking power (delivered energy). Planning to introduce a
design to a certain area will require taking a pretty good
guess that the product is in the right cooking power range.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Because
we don’t’ have the test spreadsheet with all the input
numbers it is hard to know these answers, hence all the
questions.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Dr
Nurhuda provided a photo of a pot as proof that the PM is
low for his latest stove. That is not a ‘test result’ in the
numerical sense, but we can assume it must be pretty good.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Kirk
provided some numbers from a WBT conducted at Aprovecho,
which have emissions per MJ and per unit time etc. But we
don’t have the numbers for the total MJ or the total time so
we can’t tell a whole bunch of things we need to know to
evaluate the performance or suitability. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">The
best we could do is to share the official test spreadsheet
so the missing metrics are available to those who need them.
I cannot select a stove design based on an emissions per MJ
if I don’t know how many MJ it is capable of delivering. I
can <i>rate</i> a stove I have already selected using that
metric.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">I
can’t select a stove design based on a heat transfer
efficiency if I don’t know how much heat was involved.
Similarly, the firepower combined with other metrics could
be used to determine cooking capabilities but only if I am
quite sure what that firepower number refers to: peak,
average, smoothed 3-minute peak, and so on. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">What
do we want to know?<br>
Cooking power total.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Cooking
power per sq cm.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">System
efficiency for some known and relevant task, expressed as
the “Energy Efficiency”<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Fuel
flexibility.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Cost.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Durability.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Pot
holding capacity.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Pot
stability (when stirring).<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Tilt
stability.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">PM
mass per delivered MJ (used together with the cooking power)<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">CO
mass per delivered MJ (ditto)<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Note:
the Energy efficiency is used as a proxy for relative fuel
consumption to compare stoves. Very importantly, it must not
refer to the heat transfer efficiency or any proxy of it.
That is an internal relationship, and we want the black box
version of the fuel consumption.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Most
of these numbers can be calculated from the information
recorded in a WBT spreadsheet.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Regards<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Crispin<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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