[Stoves] Test methods for cook stoves
Philip Lloyd
plloyd at mweb.co.za
Thu Mar 19 15:05:19 CDT 2015
Dear Frank
I agree that developing the improved stove is research, and that once the
improvements are proved to the developer's satisfaction there needs to be
one or more independent tests - where we differ is on defining the tests.
I believe we have to start by developing a baseline of what is actually
happening in the target community - what do they cook, how do they cook it,
what are the primary fuels, how much of those fuels do they actually use
when cooking, what utensils do they employ (if any), and what are the
emissions when they are cooking.
Then the improved stove is used with the same fuel cooking the same meal in
the same way using the same utensils to see how much fuel it uses and what
the emissions are. Only then can you be reasonably certain that you have a
better cookstove.
Timing the boiling of water, as you suggest, is not an inherently good test
because the users don't necessarily boil water rapidly. They may bring
their starchy food to the boil fairly slowly, to be certain of not burning
it, and then hold it at temperature for 20 minutes to complete the cooking.
If you then take them what you believe to be a better stove, and it DOES
burn the food, then you are lost before you have even started. Or they may
heat their plancha to nearly red-heat, and toss the meat onto it with a
smear of oil, wait 30 seconds until one side is sealed, turn it over, seal
the other side, then move it to a cooler part of the plancha to cook the
inner parts of the flesh slowly. What does your water-boiling test tell you
about that type of cooking? Absolutely nothing useful.
In a word, one protocol does not fit all. You have to develop the protocol
to suit the user, not yourself.
Good question about smoke from the actual food rather than from the fire.
Let me think about it!
I hope that helps.
Kind regards
Philip
From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Frank Shields
Sent: 19 March 2015 08:32
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Test methods for cook stoves
Dear Philip,
FRANK> Of the many testing programs I have been involved with like Drinking
water, wastewater, potting mixes, soils, compost, asbestos golf course etc.
it is never assumed following test protocol and getting the same results is
"what labs are good at." We are inspected for the right equipment, chain of
custody protocol, chemicals and knowledge and then we receive samples
through the year to test and prove we can get the correct results. My
thinking is that this is what was planned for stoves testing and they would
be looking for independent labs that could pass the requirements and become
Stove Testing facilities. But that has never seemed to be the case. So who
are the people testing the stoves and providing the data for comparison?
And do they have an unfair advantage over the small start-up backyard stove
designer? and is the testing standardize to give fair comparison?
You say "We have (MUST have) control over the biomass and task if we ever
want to have a stove test that can be sent to any qualified lab in the World
and come back with all the same results." We want to test stoves, not labs!
Labs should be able to be given a protocol and reproduce the same result
within reasonable limits. That's what labs are good at.
I thought we were trying to get a better stove - not a better test - and to
find out if one stove performs better than another in a given duty.
FRANK> Trying to get a better stove is research. All data is kept in-house
and not for the public. Once the stove has been made a 'better stove' it is
sent to the independent Stove Lab for testing and compared to the other
stoves. This is the only fair way to do this and until the stoves are tested
this way there will always be suspect and bios.
So the first problem is to define the duty, and that is almost entirely set
by the user - he/she defines the fuel and what needs to be cooked. The fuel
and what needs to be cooked will vary greatly from place to place. Then you
need some agreed metrics to measure the stove's performance in that duty.
Finally you can get to decide if one stove is better than another in that
duty. Of course, there are a host of duties - different parts of the world
really are different.
FRANK> A question: When you are cooking and measure emissions does the
volatiles from the food or oils show up on the emissions analysis? And
should we consider these along with the volatiles from just the combustion
process?
FRANK> What I am thinking is there are lots of 'duties' but few cooking
utensils. A pot for boiling water used for many things like rice and soups.
A hot plate used for many foods. So we design tests for the different
cooking utensils (without food) to be used for comparison. A test might go
like this:
Value 1)
We determine the E450v of a fuel (% by wt) that is used by all labs doing
the test and from a fuel available at the marketing location. The weigh of
fuel used in the task is determined to give us the energy used. This is a
sharp value.
Value 2)
One person holds the match in one hand and the striker in the other.
Another person has their hand on the stopwatch. When the match is struck
the Starting time begins. A sharp value.
Value 3)
Once the water starts to boil another start time is in place. We boil for 30
minutes. A fuzzy value. (Someone needs to come up with a better procedure
to determined when boiling starts).
Value 4)
At the end of exactly 30 minutes boil the stopwatch is pressed to give us
the total time to complete the task. A sharp value.
So we have only 4 values and only one is fuzzy and needs improving. That is
not a bad test. It gives us the biomass used and the time to complete the
task. Simple for a group of labs to show they know how to operate the
Champion TLUD. These values can then be used along when doing emission
testing to verify the stove was operated correctly (and reproducible) during
the emission test.
So what metrics do we use to measure whether one stove is better than
another? We could use the amount of fuel consumed in the chosen duty, but
then we have to ask if the user is really interested in the quantity of
fuel.
FRANK> The stove test (not research that determines improvements) just
provides values. The values from testing along with info on the biomass used
is published and those interested can pick out the values of interest.
The work that I have done suggests that it doesn't rank very high - once you
get to a reasonable level of fuel use, the user is happy. We could use ease
of use, but that is really difficult to measure, because the cooks learn the
tricks of the trade as they grow accustomed to a fuel/stove combination.
FRANK> Agree - the market and customer satisfaction will determine if they
like the looks and how it operates. They should be given a choice of
approved stoves that pass all the Conditions. You will soon find out the
ones they like.
The one metric that the users really seem to value is whether a stove burns
the user's choice of fuel more cleanly than another stove. If it isn't very
"clean" (however that is defined) then it is likely to taint the food being
cooked. The cleaner the burn, the less the unwelcome flavour (although
sometimes the flavour is welcomed - think smoked salmon).
FRANK> Customer satisfaction - from a list of independently tested and
approved stoves. They are all 'clean' because they made the list. Let the
dirtier of the clean list be chosen for those liking flavor.
And with "clean" as the metric, there IS something on which the
international community seems to agree. Emissions from stoves are fingered
by organisations like the World Health Organization as having an adverse
impact on people's lives - indeed, on their life expectancy. So cleaner
stoves is not merely my target - it underpins the whole rationale for the
Global Alliance, for instance. We must not be diverted into things like the
Clean Development Mechanism, whose primary target is carbon, a doubtful
candidate for a pollutant when you consider how essential the stuff is to
life. Indeed, history seems likely to view the US court's labeling of
carbon as a pollutant as one of this generation's more unlikely aberrations,
sort of like the belief in slavery 200 years ago.
FRANK> My suggestion is to test different stoves (as outlined above) to get
a base line of the fuel and time. Then adding emissions to the test package
(much like I think it is being done now) and collect the emission data.
Form a bell curve of the results and come up with limits on pm, CO etc. Base
the limits such that, perhaps, 75 % of the stoves pass. That provides
gently pressure to get better stoves and as the stoves get better the limits
can be lowered. The limits are different for each fuel group and stove type
because places that only have oily type fuels cannot expect to have
emissions of those that can burn walnut shells. (?)
There are a lot of variables to get control of. We need independent labs
providing the comparison data so there is an even playing field for all
stove designers and the data can be trusted. The train is not even going in
the right direction to accomplish this.
Thanks
Frank
Just retired : )
Frank Shields
franke at cruzio.com
Hope that helps clarify things.
Kind regards
Philip
Frank Shields
franke at cruzio.com
On Mar 18, 2015, at 12:33 PM, Philip Lloyd <plloyd at mweb.co.za> wrote:
Dear Frank
You say "We have (MUST have) control over the biomass and task if we ever
want to have a stove test that can be sent to any qualified lab in the World
and come back with all the same results." We want to test stoves, not labs!
Labs should be able to be given a protocol and reproduce the same result
within reasonable limits. That's what labs are good at.
I thought we were trying to get a better stove - not a better test - and to
find out if one stove performs better than another in a given duty. So the
first problem is to define the duty, and that is almost entirely set by the
user - he/she defines the fuel and what needs to be cooked. The fuel and
what needs to be cooked will vary greatly from place to place. Then you
need some agreed metrics to measure the stove's performance in that duty.
Finally you can get to decide if one stove is better than another in that
duty. Of course, there are a host of duties - different parts of the world
really are different.
So what metrics do we use to measure whether one stove is better than
another? We could use the amount of fuel consumed in the chosen duty, but
then we have to ask if the user is really interested in the quantity of
fuel. The work that I have done suggests that it doesn't rank very high -
once you get to a reasonable level of fuel use, the user is happy. We could
use ease of use, but that is really difficult to measure, because the cooks
learn the tricks of the trade as they grow accustomed to a fuel/stove
combination. The one metric that the users really seem to value is whether
a stove burns the user's choice of fuel more cleanly than another stove. If
it isn't very "clean" (however that is defined) then it is likely to taint
the food being cooked. The cleaner the burn, the less the unwelcome flavour
(although sometimes the flavour is welcomed - think smoked salmon).
And with "clean" as the metric, there IS something on which the
international community seems to agree. Emissions from stoves are fingered
by organisations like the World Health Organization as having an adverse
impact on people's lives - indeed, on their life expectancy. So cleaner
stoves is not merely my target - it underpins the whole rationale for the
Global Alliance, for instance. We must not be diverted into things like the
Clean Development Mechanism, whose primary target is carbon, a doubtful
candidate for a pollutant when you consider how essential the stuff is to
life. Indeed, history seems likely to view the US court's labeling of
carbon as a pollutant as one of this generation's more unlikely aberrations,
sort of like the belief in slavery 200 years ago.
Hope that helps clarify things.
Kind regards
Philip
From: Stoves [ <mailto:stoves-bounces at lists.bioenergylists.org>
mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Frank Shields
Sent: 17 March 2015 08:09
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Test methods for cook stoves
Dear Philip,
see below
On Mar 16, 2015, at 11:15 PM, Philip Lloyd < <mailto:plloyd at mweb.co.za>
plloyd at mweb.co.za> wrote:
Dear Frank
You say "There are two we are interested in when picking out a stove. (a)
biomass / task and (b) time / task"
I beg to differ. We have little choice of biomass or task - both are almost
entirely determined by the user. Then the important variable is NOT the time
for a task, but the emissions during the (pre-determined) tasks. Granted,
the shorter the time the lower the emissions are likely to be, but that
doesn't necessarily follow.
We have (MUST have) control over the biomass and task if we ever want to
have a stove test that can be sent to any qualified lab in the World and
come back with all the same results. We will continue getting nowhere, as we
have for the past ten years and continue to do so, until the basics of
method development is followed. That is, keep one variable and control all
the others so to notice changes in the one we target. We are just piling on
variables like there is no tomorrow.
Our target is cleaner cookstoves, fully accepted by users. I cannot follow
your logic in suggesting that our choice of biomass/fuel and our choice of
task can be at all relevant to achieving that target.
YOUR target is cleaner cookstoves. The person designing the legs for the
stove has a target of making the stove more stable and the person inspecting
the paint job has a target of making the stove look nice.
Emissions is no more important than the paint job because neither stove will
make it to market until those (and all) Conditions have been met.
Kind regards
Prof Philip Lloyd
Energy Institute
Cape Peninsula University of Technology
PO Box 652, Cape Town 8000
<tel:021> 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 Frank Shields
Sent: 17 March 2015 06:52
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Test methods for cook stoves
Greetings Stovers,
My suggestions:
Test methods for comparing Stoves.
1) The units of interest: There are two we are interested in when picking
out a stove. (a) biomass / task and (b) time / task
2) Variable = the Stove. We swap out different stoves, run the test and
compare the results for biomass per task and time per task.
3) Controls; there are two: (a) fuel at one end and (b) task at the other.
Control (a) Fuel
We walk up to the stockpile of fuel in town that has been gathered and piled
and pull out what we want. If we want to test a Rocket Stove using 2.5cm X
2.5cm X 10 cm long kiln dried sticks we pull out the bigger pieces and have
them sawed and dried. The rest of the pile we carry back to the forest and
scatter around under the trees. Paul for his TLUD needs uniform pieces to
keep an even flame front so he takes out what he wants, chips them to size,
and screens out the fines. The fines and overs are carried back to the
forest and scattered. Richard collects the material he can turn to mush and
sends the rest back. Stoves using pellets and sticks are done the same.
Use whatever you want as long as it comes from the pile.
Control (b) Task
The task chosen must have a clear end point. The start is easy - it's when
the match is struck.
Everything else is NOT part of the test. Our goal is to reduce by
elimination variables and get control over the ones left so the test can be
conducted at any lab and all will come out with the same results.
We don't care about the chemistry of the gases, smoke, 2.5 pm, stability of
the stove, toxic chemicals, hot surfaces that can burn, or anything else.
If Stove A works better than Stove B then check the gases, make some
adjustments and have Stove B re-tested. If, for example, Stove A completes a
task using less biomass and in a shorter time than Stove B but stove A
produces a lot of smoke - then Stove A wins.
Everything else are 'Conditions' that must be meet. There are lots of them:
paint streaked with runs on new stoves produced is a condition unacceptable,
poor welds, toxic galvanized metals, poor quality metal - all conditions
unacceptable. Smoke, toxic gases, hot surfaces or unstable are all
conditions unacceptable. Too heavy to move or won't take my favorite pot
are more conditions. But these have nothing to do with the Test. We need to
keep the Test real simple. All the Conditions in the list must pass or
don't bother doing The Test OR make corrections before testing.
Also;
Control (a) Fuel; we are interested in mass of the biomass used but we can
normalize it to energy for convenience and when comparing 'like fuels' when
the on-site fuels are not available. When measuring energy I fully agree
with the method Dean used at Stove Camp. The problem is there are so many
unknowns and guesses of the energy content of the different parts of the
fuel. Perhaps its possible to get good precision (replicates) but I can't
see how the accuracy (real value) could even be close. Therefore, without
knowing of a better replacement, I believe the E450v energy value for the
fuel is the best one to use because it is easier to determine. I realize
E450v has its own limitations.
Regards
Frank
(retired)
Frank Shields
<mailto:franke at cruzio.com> franke at cruzio.com
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