[Stoves] Effect of ambient temperature on stove testing at lowpower

Tue May 31 12:02:11 CDT 2016

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
www.facebook.com/CookswellJikos
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>
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
> www.facebook.com/CookswellJikos
> 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> 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 <plloyd at mweb.co.za>
>> *To:* 'Discussion of biomass cooking stoves'
>> <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>
>> 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 <crispinpigott at outlook.com>
>>
>> *To:* 'Discussion of biomass cooking stoves'
>> <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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