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

[Dean Still]

Dear Prof Loyd,

As I pointed out, when the stoves do the same work (hold the water at 97 C,
for example) the stove with greater heat transfer efficiency scores better.
Simmering tests are important and simmering is an important part of cooking.

The ISO process is creating new history and approaches to old problems.
Whatever emerges will certainly be defensible as the new approaches are
forged by consensus.

Best,

Dean

On Sun, Feb 15, 2015 at 12:58 AM, Philip Lloyd <plloyd at mweb.co.za> wrote:

> I am concerned that this is turning into a very fruitless discussion.
>
>
>
> On fundamental grounds the simmering test does not provide anything
> meaningful.  Crispin has demonstrated that rigorously, and others have
> pointed out that the test can score an efficient stove poorly and an
> inefficient stove well, so it does not provide any useful measure.  To go
> on defending the indefensible does not make sense, even if it did
> accentuate the need for turndown – but that need was always there, it was
> not the product of the WBT.
>
>
>
> We need defensible measures of stove performance.  Can we please turn our
> attention to developing those, and leave the indefensible to history?
>
>
>
> Prof Philip Lloyd
>
> Energy Institute
>
> Cape Peninsula University of Technology
>
> PO Box 652, Cape Town 8000
>
> Tel:021 460 4216
>
> Fax:021 460 3828
>
> Cell: 083 441 5247
>
>
>
> *From:* Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On
> Behalf Of *Paul Anderson
> *Sent:* 15 February 2015 02:26
> *To:* Discussion of biomass cooking stoves
> *Subject:* Re: [Stoves] Examples of results of simmer efficiency Re:
> [Ethos] Additional presentations at ETHOS 2015
>
>
>
> 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> 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
>
> Skype: paultlud      Phone: +1-309-452-7072
>
> Website:  www.drtlud.com
>
>
>
>
>
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