[Stoves] Effect of ambient temperature on stove testing at lowpower
Ingelore Kahrens
tutaonana at onlinehome.de
Tue May 31 12:18:10 CDT 2016
Hi Teddy,
I live in Germany but go to Kenya every year. With a Kenyan friend, I
founded the "Mount Kenya Integrated Community Development Organisation"
in the Eastern Mount Kenya region in 2009. The "basket cookers" are made
by some of the women members as an income-generating project. They are
the ones who sell them and also teach other women how to make them. The
basket cookers are a great energy-saving device when it comes to cooking
beans, sweet potatoes or cassava (overnight!) or keeping water hot for
bathing.
Cheers,
Ingelore
Am 31.05.2016 um 19:02 schrieb Cookswell Jikos:
> Hi Ingelore,
>
> Thanks for that feedback, where in Kenya are you? We tried stocking
> them at two different outlets of ours a few years ago and we only
> managed to sell one or two if I remember correctly. The main complaint
> was the ugali issue. What and how do you market yours differently? I
> really like the insulated cookers myself and use one occasionally and
> home with good results for beans.
>
> Thanks,
>
> Teddy
>
> *
> *
> *
> *
> *Cookswell Jikos*
> www.cookswell.co.ke <http://www.cookswell.co.ke>
> www.facebook.com/CookswellJikos <http://www.facebook.com/CookswellJikos>
> www.kenyacharcoal.blogspot.com <http://www.kenyacharcoal.blogspot.com>
> Mobile: +254 700 380 009
> Mobile: +254 700 905 913
> P.O. Box 1433, Nairobi 00606, Kenya
>
> Save trees - think twice before printing.
>
>
>
>
>
>
> On Tue, May 31, 2016 at 7:26 PM, Ingelore Kahrens
> <tutaonana at onlinehome.de <mailto:tutaonana at onlinehome.de>> wrote:
>
> Hello all,
>
> I have been following your discussions for some time with great
> interest. And I would like to add my experiences with
> retained-heat cookers.In our organization in Kenya we promote them
> along with improved stoves and solar box cookers. Women make the
> retained-heat cookers with baskets and like them very much. As far
> as your opinion about cooking ugali in these basket cookers is
> concerned, I have to object seriously. You start cooking the ugali
> on a fire and as soon as it is hot you transfer it to a basket
> cooker. The finished product is very tasty. This is what the women
> we have worked with have confirmed. Besides, the same holds for
> solar-cooked ugali.
>
> Cheers,
>
> Ingelore Kahrens
>
>
> Am 31.05.2016 um 17:15 schrieb Cookswell Jikos:
>> Dear Kirk -
>>
>> ''Dieter has brought up the concept of retained heat cooking in
>> an insulated container. Would anybody even need turn-down in a
>> cook stove? Is retained heat cooking the better solution, or is
>> it good to have both?''
>>
>> I think it would very much depend on what is being cooked and in
>> what type of kitchen setting. If this question of ambient
>> air temperature has more than noticeable effects on the
>> stove performance, then it is something I imagine a cook would
>> approve or disapprove of and that can make or break a sale (or a
>> 'user' using in the case of a free stove).
>>
>> Say you sell the same stove to be used in an igloo as for a
>> maasai manyatta...would your customer notice any differences that
>> would affect the quality of making dinner etc.? Retained heat
>> works for some foods, but for staples like fufu, (sima or ugali)
>> that need to be boiled, and then vigorously stirred and then
>> simmered it gets tricky as does stir-frying.
>>
>> There is (a simmering?) demand in Kenya for simmering cookstoves
>> in SME settings, the popular one right now is a smokey sawdust
>> stove that is basically a metal cylinder with a door tube that
>> you pack with saw dust around two glass bottles stacked like a
>> rocket stove - you then remove the bottles and fill with firewood
>> and light the bottom side. This lets the water boil on the
>> firewood phase and then the slow burn of the saw dust keeps the
>> water simmering. They are used by 1000's of small eatery joints
>> around Kenya for keeping goats head soup warm and also keeping
>> ugali (like polenta) warm wrapped in polythene plastic bags!
>>
>> I would like to know more about all these different tests Crispin
>> mentions - how many cookstove tests are there in total? Between
>> the VITA the ProBEC and the StarSOP, who uses which tests...do
>> the various Govts. and Donors agree on one test for the most
>> part? I do suppose though that given the phenomenal variations in
>> global cooking and fuel type that an equally complex set of
>> testing procedures would be needed. My only concern is how does
>> the end user of the stove make use of this information in their
>> day to day life? Do any of them provide for a simple
>> energy star style of rating for ease of laymans understanding?
>> What would the 'stars' be for,
>> emissions, efficiency, durability, safety?
>>
>> Many thanks,
>>
>> Teddy
>>
>> On post note:
>> In regards to cooking in igloos - Wiki says a Quilliq
>> <https://en.wikipedia.org/wiki/Kudlik#/media/File:Qulliq_1999-04-01.jpg>
>> is used to burn seal or whale fat...I wonder what tier these
>> would fall under? But could lard as a cooking energy source
>> though? Would it count as biomass? We once tried to make a jiko
>> with Dad that used the falling fat from the goat ribs to flare up
>> with enough heat to cook another set of ribs...but they were so
>> tasty we never managed to finish the experiment ;)
>>
>>
>>
>>
>>
>>
>> *
>> *
>> *
>> *
>> *Cookswell Jikos*
>> www.cookswell.co.ke <http://www.cookswell.co.ke>
>> www.facebook.com/CookswellJikos
>> <http://www.facebook.com/CookswellJikos>
>> www.kenyacharcoal.blogspot.com
>> <http://www.kenyacharcoal.blogspot.com>
>> Mobile: +254 700 380 009
>> Mobile: +254 700 905 913
>> P.O. Box 1433, Nairobi 00606, Kenya
>>
>> Save trees - think twice before printing.
>>
>>
>>
>>
>>
>>
>> On Tue, May 31, 2016 at 11:34 AM, kgharris <kgharris at sonic.net
>> <mailto:kgharris at sonic.net>> wrote:
>>
>> Prof Lloyd,
>> This is great! The heat loss from the pot is less because
>> the room temperature is higher. Thus I can't keep the water
>> temperature down. I will definately think this one through
>> and try some experiments.
>> Dieter has brought up the concept of retained heat cooking in
>> an insulated container. Would anybody even need turn-down in
>> a cook stove? Is retained heat cooking the better solution,
>> or is it good to have both?
>> Thank You,
>> Kirk
>>
>> ----- Original Message -----
>> *From:* Philip Lloyd <mailto:plloyd at mweb.co.za>
>> *To:* 'Discussion of biomass cooking stoves'
>> <mailto:stoves at lists.bioenergylists.org>
>> *Sent:* Tuesday, May 31, 2016 12:59 AM
>> *Subject:* Re: [Stoves] Effect of ambient temperature on
>> stove testing at lowpower
>>
>> Dear Kirk
>>
>> I have lurked during this discussion – forgive me for
>> entering it now.
>>
>> You believed “the increase in ambient room temperature
>> had changed the turn-down performance of the stove.”
>>
>> You may have been mistaken. I think what happened was
>> that the ambient room temperature changed the measurement
>> you were attempting to make. At the higher ambient
>> temperature there was less rate of heat loss from the
>> cooking pot, so it took less fuel to keep it hot and the
>> turndown ratio – as you define it – changed. So the
>> problem may lie with your definition of the turndown
>> ratio. I use the minimal sustainable firepower,
>> determined from the rate of fuel feed which just keeps
>> the fire going, as my lower measure, and the maximum
>> firepower I can achieve without significant oxygen
>> starvation as the upper one, and have yet to see the sort
>> of effect of ambient temperature on the ratio of the
>> upper to the lower that you report with your definition
>> of the ratio.
>>
>> In a word, you may be picking up a change in the heat
>> transfer from the pot as the ambient temperature changes,
>> rather than anything fundamental about the stove performance.
>>
>> I hope that suggestion assists.
>>
>> Kind regards
>>
>> Prof Philip Lloyd
>>
>> Energy Institute, CPUT
>>
>> SARETEC, Sachs Circle
>>
>> Bellville
>>
>> Tel 021 959 4323
>>
>> Cell 083 441 5247
>>
>> PA Nadia 021 959 4330
>>
>> *From:*Stoves
>> [mailto:stoves-bounces at lists.bioenergylists.org
>> <mailto:stoves-bounces at lists.bioenergylists.org>] *On
>> Behalf Of *kgharris
>> *Sent:* Tuesday, May 31, 2016 8:08 AM
>> *To:* Discussion of biomass cooking stoves
>> *Subject:* Re: [Stoves] stove test
>>
>> Crispin,
>>
>> My original statement was to point out how the increase
>> in ambient room temperature had changed the turn-down
>> performance of the stove. This is an important topic if
>> the stove principles are going to have any effect in hot
>> tropical countries. If you can comment on this I would
>> be happy to learn from your experience, but please stop
>> hijacking my posts and misdirecting attention to cater to
>> your agenda against the current test methods. Start your
>> own thread if that is what you want to talk about.
>>
>> All,
>>
>> I will be happy to answer questions about the burning
>> abilities and tecniques of our stove and combustor.
>>
>> Kirk
>>
>> ----- Original Message -----
>>
>> *From:*Crispin Pemberton-Pigott
>> <mailto:crispinpigott at outlook.com>
>>
>> *To:*'Discussion of biomass cooking stoves'
>> <mailto:stoves at lists.bioenergylists.org>
>>
>> *Sent:*Monday, May 30, 2016 9:40 PM
>>
>> *Subject:*Re: [Stoves] stove test
>>
>> Dear Kirk
>>
>> >With the support of Aprovecho Research Center, I
>> (actually we) have developed a very good, clean
>> burning TLUD-ND.
>>
>> I think you have done exactly that. Good on you.
>>
>> There is no misdirection at all here. You are past
>> the verge of changing the stove’s superior
>> performance in order to get a better rating on an
>> invalid metric. It is that simple. Don’t get sucked
>> into that trap. When you are getting results as good
>> as you are, there are new opportunities to go wrong.
>>
>> The only ‘misdirection’ has been supplied for years
>> by test methods that guided people to edit their
>> stoves to meet spurious requirements that did not
>> bear directly on performance, or worse, actually
>> penalised stoves for their superior performance. A
>> good example is attached.
>>
>> This is not something new in the stove community.
>> Here is a quote from the attached Aprovecho document
>> from 2003:
>>
>> /“Why was the good advice, by established experts in
>> the field, represented in the VITA International
>> Standard test, the result of several well funded
>> international conferences, obscure in 2003? Both the
>> Indian and Chinese governments developed tests of
>> their own widening the scope of PHU to include power,
>> rate of evaporation, time. Visser (2003) published a
>> version of a water boiling test based on efficiency
>> and appropriate power for boiling and simmering. What
>> motivated this parallel activity? Why isn’t the VITA
>> test in more general use?”/
>>
>> One reason the VITA test was not more popular was it
>> had several conceptual errors and a few really poor
>> metrics that gave mis-directing outputs. One is the
>> efficiency of simmering, another is the concept of
>> specific fuel consumption for simmering. Another was
>> the idea of an ‘average efficiency’ meaning an
>> ‘average thermal efficiency’. I believe from my
>> research that the specific fuel consumption for
>> simmering and the average efficiency were both
>> introduced by Baldwin in 1986 or so, before his book
>> came out. Neither are acceptable metrics.
>>
>> The document refers to the VITA test the
>> ‘international standard’ which is not supported by
>> the evidence. Three or four minor parties agreed to
>> it and it was never used by the major markets in
>> India and China. Even Eindhoven University didn’t use
>> it and they were a party to drafting it. India pretty
>> much adopted the minority position taken by KK Prasad
>> from Eindhoven and built that into their 1991 test.
>> The Chinese test from that era was very similar.
>> India, interestingly, produced a list of 28 standard
>> sizes of cooking pot which is a record, I believe!
>>
>> The long-forgotten organisation Bois de Feu had a
>> clear understanding of these issues and had a test
>> method in 1982 that didn’t have these problems. They
>> treated the simmering phase very carefully (and
>> differently). Prasad (and Visser who was his student)
>> developed multiple test methods over the years. Piet
>> Visser and I created one in Malawi in about 2007
>> which later evolved into the ProBEC Test for heat
>> transfer efficiency which is now a SeTAR SOP,
>> currently v1.05 (SeTAR is an independently managed
>> continuation of the 13 year long GIZ/ProBEC project).
>> It doesn’t really predict performance, it gives a
>> real-time heat transfer efficiency report under
>> varying conditions. It is very easy to perform and it
>> supports pot-swapping, similar to the Indian protocol.
>>
>> So, ladies and gentlemen, there are no Tier 4 stoves.
>> That achievement will have to wait for the
>> development of appropriate, valid low power metrics
>> and one will need an equipment set capable of
>> quantifying the result.
>>
>> Kirk: don’t be bamboozled. You are doing good work.
>> Nothing is perfectly correct. Independent
>> investigation of truth is still required.
>>
>> Best wishes
>>
>> Crispin
>>
>> All,
>>
>> With the support of Aprovecho Research Center, I
>> (actually we) have developed a very good, clean
>> burning TLUD-ND. This is real and proven and no
>> amount of misdirection can change that. It will be
>> at Aprovecho for stove camp for all to examine, and I
>> will be giving a presentation on how it burns so clean.
>>
>> Respectfully,
>>
>> Kirk
>>
>> Santa Rosa, CA. USA
>>
>> ------------------------------------------------------------------------
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