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<div class="moz-cite-prefix">Dear Jiddu, and to all who share the
concerns about errors in testing of stoves.<br>
<br>
Your comments are greatly appreciated. Well said. As we make
progress on these topics, the comments will be continually refined
for clarity of expression, and will be the composite work of too
many people to be individually named. Thank you.<br>
<br>
To know of your credentials as a theoretical physicist is
appreciated. There could be people with credentials on both or
all sides of the discussion. But you can talk to other
physicists much better than I can. In debates (and courtrooms)
both sides like to have their expert witnesses. Thanks for
stepping forward. <br>
<br>
I especially like your comment that shows your convictions:<br>
<blockquote type="cite"><font face="Arial">I find myself in the
position where I have to tell my company to produce stoves
with lower rating because it will be better for women that we
build them for.</font></blockquote>
That is worth re-reading and repeating!!!<br>
<br>
As I get further into this topic, I am realizing that invalid
metrics must be STOPPED. I do not yet know how much they have
hurt various stove designs, but I can see no way that such metrics
have been of any positive value. ------<br>
<br>
----- Oh, and if some stoves are benefited by such inaccurate
metrics, and if the manufacturers know that they have made claims
based on faulty testing, THAT would be truly reprehensible. <br>
<br>
It is fast becoming (in my opinion) the time when the defenders of
the status quo about the three Low Power measurements in the WBT
will need to speak up with some quite convincing arguments.<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>
On 2/19/2015 1:56 AM, Jiddu Broersma wrote:<br>
</div>
<blockquote
cite="mid:CALaGYMxF43yTxBmsatC3eGLaggA0QCHEcSAwzmbqgk2YKTehdA@mail.gmail.com"
type="cite">
<div dir="ltr">Dear All,
<div><br>
</div>
<div>First,</div>
<div>Paul, thank you for keeping the conversation going with
great intentions. Much appreciated.</div>
<div> <br>
</div>
<div>I have been a quiet follower of the stovelist and I just
caught up on the simmering discussion. I believe it is a
necessary discussion.<br>
</div>
<div><br>
</div>
<div>I would like to share my opinion. It is one from the
perspective of a stove manufacturer and a theoretical
physicist. <br>
I do this purely to contribute to the discussion. Although I
will formulate my opinion direct with strong language, I want
to assure you all that I value everyone's opinion equally.</div>
<div>Now, I will jump straight into the low power metrics.</div>
<div><br>
</div>
<div><span
style="font-stretch:normal;font-size:13px;font-family:Arial"></span><b>Simmering</b><br>
As has been explained, simmering is a 'zero work' task, it
does not have an efficiency. Evaporating water and overcoming
heat losses require work, they can have an efficiency.
However, is anyone interested in knowing the efficiency of
evaporating water? Or is anyone calculating how much energy is
lost from the pot?</div>
<div><br>
</div>
<div>Either way, simmering is only a term that we will hopefully
agree on. Most important is to understand the meaning of the
metrics that are calculated: Low power specific fuel
consumption, Low power CO and Low power PM.</div>
<div><br>
</div>
<div><b>Low Power Specific Fuel Consumption</b></div>
<div>From the WBT sheet I find that (equation)</div>
<div>Low power specific fuel consumption = (weight fuel consumed
* calorific value of fuel ) / (weight of water remaining *
minutes of simmering * 1000)</div>
<div>To explain in steps: </div>
<div>
<ol>
<li>Weight of fuel consumed divided by minutes simmering is
the burn rate.<br>
</li>
<li>If we multiply this by calorific value we get the energy
released by the combustion per minute. Let's call this the
'energy rate'.<br>
</li>
<li>If we divide this weight of water remaining we just
divide it by a random number that has no meaning. Keeping
more food/water hot does not require more energy. (I
believe it does the contrary, because volume grows faster
than surface when you increase quantities)<br>
</li>
</ol>
</div>
<div>-> We have the energy released by the combustion divided
by a random number.</div>
<div><br>
</div>
<div>If we wish to calculate some kind of efficiency number we
require useful energy (into pot) divided by used energy (from
combustion). What we have calculated is nothing close to this.<br>
</div>
<div><br>
</div>
<div>We could possibly calculate the energy into evaporation and
heat loss from the pot, but we have no interest in this. </div>
<div>Hence, a simmering task can't give us a useful efficiency
type of number!</div>
<div><br>
</div>
<div>That was me as a physicist, as a employee of a manufacturer
I am concerned that stoves are unfairly compared. Because the
system can be manipulated to gain better results by using a
pot with larger volume capacity and higher insulating
properties. </div>
<div>Also another big issue is that more efficient stoves can
have lower rating at the same power output. I'll explain by
example (as others have done before me):</div>
<div><i>Two stoves are equal except that one has better heat
transfer efficiency. When they both run at the lowest power
possible (which is the same power for both), the one with
the better heat transfer efficiency will have likely
evaporated more water because more energy went into the pot.
Do to more evaporation it will end up with a rating that is
worse!</i></div>
<div><br>
</div>
<div>
<span
style="font-stretch:normal;font-size:13px;font-family:Arial"></span><b>Low
power Emissions</b><br>
<span
style="font-stretch:normal;font-size:13px;font-family:Arial">Both
PM and CO are given in </span></div>
<div><span
style="font-stretch:normal;font-size:13px;font-family:Arial">weight
/ (minute * liters of water)</span></div>
<div><span
style="font-stretch:normal;font-size:13px;font-family:Arial"><br>
</span></div>
<div><span
style="font-stretch:normal;font-size:13px;font-family:Arial">Similar
breakdown:</span></div>
<div><span
style="font-stretch:normal;font-size:13px;font-family:Arial">Weight
of emissions per minute is straightforward.</span></div>
<div><span
style="font-stretch:normal;font-size:13px;font-family:Arial">Dividing
this by number of liters in the pot is simply dividing the
emissions by a number of your choice (the liters you fill in
the pot). It has no value to stove rating.</span></div>
<div><span
style="font-stretch:normal;font-size:13px;font-family:Arial"><br>
</span></div>
<div><font face="Arial">Generally I think that weight of
emissions per minute is not a bad metric. However, simmering
is not a task that can be compared fairly between two stoves
because it is not a specific task! If we can't compare the
way two stoves simmer because we know nothing about the
useful energy that went into the pot we are not allowed to
compare the results because it means nothing without enough
information.</font></div>
<div><span
style="font-stretch:normal;font-size:13px;font-family:Arial"><br>
</span></div>
<div><font face="Arial"><b>Wrap-up</b></font></div>
<div><font face="Arial">The list of complications that result
from these invalid simmering metrics goes on. Please read
again Crispin's and </font><span
style="color:rgb(0,0,0);font-size:12.8000001907349px">Philip
Lloyd's comments for a more comprehensive list. </span></div>
<div>
<span
style="font-stretch:normal;font-size:13px;font-family:Arial"></span><br>
<span
style="font-stretch:normal;font-size:13px;font-family:Arial">Worst
is that many manufacturers are optimizing their products
using the WBT and that stoves are not actually improving in
the field. The WBT can result into the production of bad
stoves for millions of already suffering women! </span><font
face="Arial"><br>
</font></div>
<div><font face="Arial">I find myself in the position where I
have to tell my company to produce stoves with lower rating
because it will be better for women that we build them for.</font></div>
<div><br>
</div>
<div><font face="Arial">It is not a matter of right or wrong, it
is a matter of how we stimulate the production of stoves
that are really improving lives. </font></div>
<div><font face="Arial">My opinion is that we need to review the
meaning of metrics at fundamental level. </font><span
style="font-family:Arial;font-size:13px">(Ie. Boiling and
simmering are not scientific ways of describing a state of
cooking for stoves).</span></div>
<div><br>
</div>
<div>Due to the differences in opinion in the stove world, I
believe an external review (scientific: engineers, physicists,
mathematicians) would be the most suitable option. The review
could simply explain the physical meaning of all calculated
results. </div>
<div><br>
</div>
<div>Best regards,</div>
<div>Jiddu</div>
<div><br clear="all">
<div>
<div class="gmail_signature">
<div dir="ltr"><font
style="background-color:rgb(255,255,255)"
color="#666666"><b>Jiddu Broersma</b></font>
<div><font color="#666666"><b>Technology and
Organization Officer</b></font>
<div>
<div><br>
</div>
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</blockquote>
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