[Stoves] air velocity

Wed Mar 21 03:27:42 CDT 2012

Sarbagya,

You might check out this page to get you started on a theoretical estimate:
http://www.cookstove.net/comb-chamb-design/air-supply.html
It focuses on the stove types you just mentioned.
(I can't speak for cookstove.net's accuracy, but it will at least get you
started)

For our back-of-the-enveloped calculations, we would use a combination
ofstack effect<http://en.wikipedia.org/wiki/Stack_effect>,
stoichiometric air requirement, and excess air. Worked well enough for our
purposes (design by negative selection), but won't be enough for
quantitiative modeling.

Marc Paré
B.S. Mechanical Engineering
Georgia Institute of Technology | Université de Technologie de Compiègne

my cv, etc. | http://notwandering.com

On Wed, Mar 21, 2012 at 2:42 PM, Sarbagya Tuladhar <sarbagya007 at gmail.com>wrote:

> Hi Mr Kavre,
>
> Thanks a lot for the info.
>
> What would you say would be the air velocity for the Prakti Leo stove (2
> pot chimney) or any similar kind of 2 pot stove( natural convection)
>
> Cheers
> Sarbagya Tuladhar
>
> Sent from my iPhone
>
> On 21/03/2012, at 2:42 PM, Anand Karve <adkarve at gmail.com> wrote:
>
> Dear Mr. Tuladhar,
>  One can generalise that the air entering the stove goes out through the
> pot hole and the chimney. There are stoves in which the volume of
> air entering the stove through the grate is reduced while that of the
> scondary air entering the stove through the firemouth is enhanced. There
> are also stoves in which the pot sits flush on the stove, so that all the
> outgoing air has to pass through chimney. But there are also chimneyless
> stoves. Thus, the amount of air entering or leaving the stove through
> various inlets and outlets and their velocities depend very much on the
> stove design.
> Yours
> A.D.Karve
>
>
>
> On Mon, Mar 19, 2012 at 1:34 PM, Sarbagya Tuladhar <sarbagya007 at gmail.com>wrote:
>
>> Hi Stovers,
>>
>> Just veering off the topic of dung for a moment, has anyone got any kind
>> of data on the air velocity for natural convection stoves.. Any kind of
>> data would be useful ? Could be air velocity at the cooktops or the chimney
>> ? I suppose the max velocity would be at the chimney area due to the
>> chimney effect (draft)..
>>
>> Cheers
>>
>> Sarbagya
>>
>> On Mon, Mar 19, 2012 at 4:27 PM, Sarbagya Tuladhar <sarbagya007 at gmail.com
>> > wrote:
>>
>>> Interesting indeed. However stink is not as much a problem when dried
>>> completely. Even with the dung briquettes, the stink is no more when dried.
>>> However, the case with pyrolyzing the dung and releasing the hamrful
>>> toxins, if the smoke and aroma can be removed then thats certainly worth a
>>> try. Any more info on Francis of Kenya ?
>>>
>>> Cheers
>>> Sarbagya
>>>
>>>  On Mon, Mar 19, 2012 at 12:16 PM, Richard Stanley <
>>> rstanley at legacyfound.org> wrote:
>>>
>>>> This is interesting. Out in Miumbuni village, about 2hrs east of
>>>> Nairobi and another hr off the Mombassa road, is a one Francis Kavita who
>>>> has been working with the Masaai in developing cow dung based briquettes
>>>> that do not stink: He has developed same with elephant dung in south
>>>> Eastern Kenya (near Tasavo)  and is now breaking ground with camel dung
>>>> based blends for use in the refugee camps in Somalia. He has tested them
>>>> and he says the work well without smoke or aroma.
>>>> He has no numbers for
>>>> what he ahas done but is still far more experience than anyone else,
>>>> including all the Phd students we know of. If he says it will work I
>>>> believe it:
>>>>
>>>> We started him in briquette making in 1999, and trained he and his wife
>>>> Mary in 2007 as trainers and they have been all over east Africa training
>>>> others–on their own–, ever since.  The problem is not that it works or does
>>>> not work, Its a case of what we need to be convinced of it. The Phd study
>>>> or   Francis' experience. After all he only has a 4th grade education.
>>>>
>>>> Alternatively, can we evolve a more balanced discovery model with due
>>>> respect for the unique contributions of knowledge and experience that *
>>>> both* have to offer.
>>>>
>>>> Richard Stanley
>>>> www.legacyfound
>>>> ==========
>>>>
>>>>
>>>>
>>>>  On Mar 16, 2012, at 9:26 PM, SARBAGYA TULADHAR wrote:
>>>>
>>>> Hi Stovers,
>>>>
>>>> I am undertaking my uni graduate project on the  Use of CFD for the
>>>> study of heat transfer and convection in a Dung Burning Cookstove. With
>>>> this project, a heat transfer and convection analysis would be carried out
>>>> using Computational Fluid Dynamics (CFD) for the optimization of dung
>>>> burning cooktove that is currently being developed in Nepal. The analysis
>>>> would involve simulation to predict the performance of the cookstove and
>>>> would set up a benchmark for improved stove manufacturing in Nepal. This
>>>> analysis would also assist in providing the experimental and the simulation
>>>> results towards getting the stove certified as an “Improved Cookstove”.
>>>>
>>>> However to simulate the dung burning I had to resort to using the fixed
>>>> heat source instead as modeling combustion/pyrolysis of dung was beyond the
>>>> scope of the project. So what could be the heat output from burning 1 kg.
>>>> of dung. How mush heat would be released from this ? Is that the calorific
>>>> value dung ? As I would be using a fixed temperature heat source, what
>>>> could be that temperature ?
>>>>
>>>> Cheers
>>>>
>>>> Sarbagya Tuladhar
>>>>
>>>>  On 13/02/2012, at 2:27 AM, Anand Karve wrote:
>>>>
>>>>  Dear Richard,
>>>>  The undigested solid matter in the dung is in fact the lignocellulosic
>>>> matter, However, in the case of ruminents, it is not in a fibrous form but
>>>> in the form of particles due to the practice of chewing the cud.  It is the
>>>> dung of non-ruminents, like horses and elephants that has fibres.
>>>> Yours
>>>> A.D.Karve
>>>>
>>>> On Sat, Feb 11, 2012 at 11:30 PM, Richard Stanley <
>>>> rstanley at legacyfound.org> wrote:
>>>>
>>>>> Ad,
>>>>>
>>>>>  I don't personally think the solids would be of much value for a good
>>>>> briquette:  What I would look for personally, is  your lignocellulosic
>>>>> material, ( the more fibrous stuff)  to encapsulate other more carbon rich
>>>>> salt free, materials sawdust charcoal crumbs/ dust, selected agro residues
>>>>> with aromatic-or non aromatic- considerations depending upon what kind of
>>>>> fuel aroma and duration of heat you desire.
>>>>>
>>>>> Richard Stanley
>>>>>
>>>>>
>>>>>  On Feb 10, 2012, at 9:36 PM, Anand Karve wrote:
>>>>>
>>>>> Cattle dung consists mainly of non-digestible lignocellulosic
>>>>> material, millions of micro-organisms, mucus produced by the animals and
>>>>> by the microbes, and some minerals. In fact it is the microbes and the
>>>>> mucus in the dung that yield biogas on anaerobic fermentation.
>>>>> A pressurised sieve, technically called a filter press, is the best device
>>>>> for separating the non-soluble solids from the fluids. If the fluids
>>>>> contained the microbes and the mucus, they should be subjected to anaerobic
>>>>> digestion before allowing them to be used as manure.  Dung also has a very
>>>>> high ash content, because of which its calorific value is rather low. Dry
>>>>> dung has calorific value of about 3500 kcal/kg.  Has anybody measured the
>>>>> calorific value of the solids in the dung, after removal of the fluids from
>>>>> it by using a filter press?
>>>>> Yours
>>>>> A.D.Karve
>>>>>
>>>>> On Sat, Feb 11, 2012 at 8:27 AM, Sarbagya Tuladhar <
>>>>> sarbagya007 at gmail.com> wrote:
>>>>>
>>>>>>  Hi Boston
>>>>>>
>>>>>>
>>>>>> I volunteered with EWB Australia in Nepal working on a clean dung
>>>>>> burning stove and thus worked with the dung as a fuel . Washing of the dung
>>>>>> was done and briquettes which was a real success. Paper pulp used as a
>>>>>> binder worked really well. Also the chloride contents of the dung which is
>>>>>> responsible for watery eyes was removed on washing the dung which was
>>>>>> proven by the copper wire test. We even fabricated a simple dung press for
>>>>>> the same. The liquid portion of the dung was reutilised as manure in the
>>>>>> fields. Thus the whole sceptism about "should" use dung as manure in the
>>>>>> fields and not as a cooking fuel was somewhat solved. Did not test the NPK
>>>>>> contents of the liquid portion though...
>>>>>>
>>>>>> Sarbagya
>>>>>>
>>>>>> Sent from my iPhone
>>>>>>
>>>>>> On 11/02/2012, at 2:06 AM, Boston Nyer <bostonnyer at gmail.com> wrote:
>>>>>>
>>>>>>  Hello,
>>>>>>
>>>>>> I'm looking to clean/rinse cow dung and do not have any experience
>>>>>> doing so.  Does anyone have any experience cleaning dung and would like to
>>>>>> share?
>>>>>>
>>>>>> Thank you!
>>>>>> Boston
>>>>>>
>>>>>> --
>>>>>> Boston
>>>>>>  Skype: BostonNyer
>>>>>> Cell: (585) 503-3459
>>>>>> www.burndesignlab.org
>>>>>>
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>>>>>
>>>>>
>>>>> --
>>>>> ***
>>>>> Dr. A.D. Karve
>>>>> Trustee & Founder President, Appropriate Rural Technology Institute
>>>>> (ARTI)
>>>>>
>>>>>
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>>>> --
>>>> ***
>>>> Dr. A.D. Karve
>>>> Trustee & Founder President, Appropriate Rural Technology Institute
>>>> (ARTI)
>>>>
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>>
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>
>
> --
> ***
> Dr. A.D. Karve
> Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)
>
>
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