[Stoves] The need to continue the discussion Re: simmer efficiency
Paul Anderson
psanders at ilstu.edu
Sun Feb 15 22:46:41 CST 2015
Dear Philip, and to Dean and all,
Philip wrote:
> I do not think we should waste much more time arguing about them –
> they are fundamentally wrong.
It is precisely because things are (or might be) wrong that we need this
time for discussion, even if it is a form of arguing. To not press for
clarification (and a possible reversal) of what Dean is so staunchly
defending would be to yield to the status quo of the testing procedures.
Crispin has been rather lonely as the outspoken critic of the status quo
WBT. It is interesting to hear such a solid support by you (Philip).
It would be good to hear from others who agree with Crispin's comment:
> The variables selected [for Low Power testing] are inappropriately
> chosen. ....
But Crispin and you give an incorrect comment when saying:
> .... We have to move on.”
The time is NOW to keep this discussion going until there is
resolution. It might take a while, but as I see it, there are at least
two CAMPS or lines of thinking about the Low Power measurements in the
stove testing. Dean seems to present much of the thinking found in the
USA, with some (but probably not all) supporters in the GACC and EPA.
Crispin suggests that at least some other countries and agencies are
supportive of his line of reasoning (China, Indonesia, South Africa,
World Bank). But certainly that also is not 100% locked in.
Perhaps there is a totally different method or two. Perhaps the
current method and an alternative are BOTH meaningful. But I doubt
that. I am a stove designer, not an equation-using physical-chemical
scientist. So I will win when whichever testing methodology is found
to be correct. And I am VERY CONCERNED that in 2015 we still need this
discussion and debate. But it must be resolved!!!!!!!!!!!
Dean commented (and I think I did not take it out of context):
> ... the new approaches are forged by consensus.
"Consensus" will prevail (and there will be some who will never join the
consensus). But consensus is not to be based on democratic votes or
even a slight majority number of nations adopting some set of
standards. What must prevail is the SCIENCE associated with the
testing procedures.
We should not be here trying to get votes like politicians. We need to
be hear sound scientific arguments. So, my requests are:
Philip, (and others) please help explain what is incorrect with the Low
Power testing measurements and calculations. Most specifically, the
use of a variable called "amount of water boiled away during simmering"
seems to be in question. (also expressed as weight of water in pot at
end of simmering time).
Dean, (and others) please help explain how the boiling away of water
during simmer time _has meaning in the calculations_ . We understand
that evaporated water represents heat energy that exits the system.
But the system is about maintaining a boiling point (or slightly below),
and that task is accomplished whether the evaporation is of 0 or 100 or
300 or 500 or more grams of water.
AND we know the amount of fuel that was consumed. What is important is
the fuel consumption, and we do not need "weight of evaporated water "
to know the fuel consumption. There is no "work" in simmering except
to keep the water in the pot from going below the minimum allowed
temperature. And the water temperature cannot possibly go above the
boiling point (unless in a pressurized vessel, which is not an allowed
consideration).
To all: Please help us all to see the formulae (three of them, for
efficiency, CO and PM) that are in the current version of the testing
protocol. The document is public and on the Internet. Please help us
find the right specific pages. I will not pretend to understand such
formulae, but with help, I want to boil it down to the issue of the
evaporated water. Does it matter? Should it matter?
I am most focused on the formula for efficiency, but all three with
survive or fall together with the understanding of the impact of the
amount of water that is evaporated during simmering.
This is NOT the time to turn away from this discussion.
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
On 2/15/2015 1:43 PM, Philip Lloyd wrote:
>
> Dear Dean
>
> Crispin said it well:
> “The three low power metrics are invalid. The variables selected are
> inappropriately chosen. The calculated results are misleading and
> contrary to any claim [that] they provide guidance for product
> development or selection. We have to move on.”
>
> I have looked at the simmering metrics in WBT 4.3.2 and can only
> concur. That is why I do not think we should waste much more time
> arguing about them – they are fundamentally wrong. Yes, stove
> designers need to be concerned with simmering and turndown; no, the
> WBT simmering metrics do not provide them with guidance, and can be
> positively misleading, which is worse.
>
> Kind regards
>
> Philip Lloyd
>
> *From:*Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On
> Behalf Of *Dean Still
> *Sent:* 15 February 2015 06:38
> *To:* Discussion of biomass cooking stoves
> *Subject:* Re: [Stoves] Examples of results of simmer efficiency Re:
> [Ethos] Additional presentations at ETHOS 2015
>
> 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
> <mailto: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
> <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 <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>
>
> 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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