[Stoves] Examples of results of simmer efficiency Re: [Ethos] Additional presentations at ETHOS 2015

[Paul Anderson]

Dear Dean,    my reply is below:

Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
Email:  psanders at ilstu.edu
Skype: paultlud      Phone: +1-309-452-7072
Website:  www.drtlud.com

On 2/14/2015 1:06 PM, Dean Still wrote:
> Dear Paul,
>
> To do well on the Low Power Specific Consumption metrics the stove has 
> to have a good Turn Down Ratio. In other words, the stove has to have 
> high power and low power.
I totally agree with this.   But it is not the whole story of LPSC.   
Other factors influence LPSC, especially concerning the measurement of 
the variables that are used to make the calculation.   These can include 
the insulation of the pot (incl. skirts), lid on pot, pot 
characteristics such as size, quantity of water in the pot at the start, 
and at the finish.
>
> Specific Consumption is based on how much energy was used to create 
> simmered water.
Simmered water is not created.   It was already hot at the start of the 
simmer phase of testing.   We are interested in how much energy is used 
to MAINTAIN the required temperature near boiling, but preferable about 
3 degrees C lower than that boiling temperature. In fact, a 
super-insulative pot could need barely a flicker of a flame, and 
therefore even a well turned-down stove could cause the water to boil 
and evaporate.
> If the stove only operates at high power there is more steam made and 
> [at the end of testing] less simmered water remains....
that is true.   but continue.
> ..... so energy was used to create less product.
Stove simmering is not creating a product.   It is maintaining a 
temperature.   The steam that is driven off does not represent loss of 
"product" which should be understood to be "cooked food" (and not 
meaning water that can be added to the pot by any attentive cook in a 
household.)
>
> I like Specific Consumption because it forces stove designers to make 
> stoves that simmer successfully, not just boil water.
I agree.   But the measurement procedures need to accurately document 
the ability to have that strong turn-down ratio, without calculations 
that can yield ambiguous or mis-leading results.
> For example, new TLUDs are better stoves because they have both high 
> power and low power. In my opinion, the WBT 4.2.3 helped to create 
> these more successful TLUDs.
The cause-and-effect relationship is not totally clear.   We have wanted 
turn-down capabilities in TLUDs for many years.
>
> As Sam says, we are working on a paper showing characteristics of the 
> WBT 4.2.3 for the ISO work. Knowing the characteristics lets folks 
> evolve a perfect test.
I question the above wording to "evolve a perfect test" (which is a test 
run, not the test procedures.)   Maybe the statement should be that 
"knowing the characteristics let's folks operate their stoves in special 
ways to obtain superior results that are not realistic for average 
users."  OR "... let's folks 'game the metrics' to present 'perfected' 
test-results BASED ON OPERATIONAL PROCEDURES AND NOT ON IMPROVEMENTS TO 
THE STOVES THEMSELVES."

OR it could be that flawed protocols /procedures (such as dividing by 
the volume of remaining water after simmering) can yield numerical 
results that are questionable and perhaps disadvantageous to the 
development of clean cookstoves.
>
> Sam is doing great work as he crunches all the data....
absolutely.   But we are questioning if the numbers are as valid and 
useful as claimed.
>  and gives ISO real numbers to work with in their discussions.

Concluding statement:   The topic of Low Power Specific Consumption is 
too important to just brush aside the stated issues.   More "expert 
testimony" would be useful, including a mathematical analysis of the 
impact of the parts of the calculations.

Paul


>
> Best,
>
> Dean
>
> On Sat, Feb 14, 2015 at 8:18 AM, Paul Anderson <psanders at ilstu.edu 
> <mailto:psanders at ilstu.edu>> wrote:
>
>     Dear Tom H.,         and to all who are interested in proper
>     testing of stoves.
>
>     Your reply about your experiences is helpful.   Sounds like you
>     had qualified testing center do the testing, in accordance with
>     the procedures that Crispin is questioning.   Please send to me
>     the full details. Could be off-list, but this is sufficiently
>     important that we will want the full results known.
>
>     I have a specific case of official testing of one of my stoves
>     with unfavorable results for Low-Heat Efficiency (simmering).   I
>     will add that into the list of examples and provide the details
>     very soon.
>
>     I invite anyone else who has something to report about simmering
>     efficiency to also send details of their experiences, either
>     favorable or unfavorable or neutral.
>
>     The examination of the questionable methods about simmer
>     efficiency might take some days, maybe weeks.   But not the months
>     or years that this debate has been "simmering".
>
>     Remember:  A testing center that properly conducts testing using
>     an endorsed but possibly flawed procedure is NOT a culprit.  The
>     culprit is the testing protocols, _IF found to be faulty. _And we
>     hope that the testing center people (employees and leaders) who
>     understand the technical aspects of the calculations will be among
>     those who can help resolve these serious issues.
>
>     Even those who developed protocols that are eventually shown to be
>     faulty are not culprits.   Mistakes can be made.    However, the
>     culprits can include those who advocate a protocol that he or she
>     knows (or reasonably suspects) to be faulty.
>
>     Paul
>
>     Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
>     Email:psanders at ilstu.edu  <mailto:psanders at ilstu.edu>    
>     Skype: paultlud      Phone:+1-309-452-7072  <tel:%2B1-309-452-7072>
>     Website:www.drtlud.com  <http://www.drtlud.com>
>
>

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