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2013/11/20 <[email protected]> > Send Stoves mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org > > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Stoves digest..." > > > Today's Topics: > > 1. Re: Cajun Rocket Pot Tested (Ronal W. Larson) > 2. Household Burns from cookstoves. (Cookswell Jikos) > 3. Re: In search for a stove model for the disaster in the > Philippines (Joshua Guinto) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 18 Nov 2013 22:33:37 -0700 > From: "Ronal W. Larson" <[email protected]> > To: Discussion of biomass <[email protected]>, Dale > Andreatta <[email protected]> > Subject: Re: [Stoves] Cajun Rocket Pot Tested > Message-ID: <[email protected]> > Content-Type: text/plain; charset="utf-8" > > Dale and Crispin: > > This is to try to close the gap a bit. Dale reports for his home gas > range testing two differences in efficiency: 8.8 and 13.5 (the ?knobby > aluminum? over the steel). Crispin says the efficiency should be strongly > modified by the materials and weight differences - which I can see makes > sense. > > My problem is that playing around with Dale?s stated power levels ("The > power input to the regular pot was 1128 Watts, while that of the finned pot > 1227 Watts, or 1.088 times as much."), I can?t see from the given data, > how Dale got those power numbers. I think there should have been some > water evaporated, but none is stated. Did the 700 watt number come in some > way? > > So, Dale, can you show the computations you used to get 1128 and > 1227.? Adding in the specific heat of the pots (if you didn?t - and you > might have) should help with better understanding both this geometry and > the importance of including what Crispin wants to include. > > Ron > > > > > > On Nov 18, 2013, at 4:57 PM, Crispin Pemberton-Pigott < > [email protected]> wrote: > > > Dear Dale > > > > What a welcome report on a promising technology! > > > > I have several points that I?d like to raise which probably impact > materially on your concluding numbers. > > > > I am happy to see at the end a discussion of the thermal mass of the > pots and the fact they have different materials and different masses. > Because the tests were conducted to check the heat transfer efficiency and > the overall fuel consumption (two different metrics) at high and low power > (again, two different metrics) I feel it is important to put the thermal > mass in context at the beginning then move to the other points. > > > > The British, Indian, SeTAR and Indonesian heat transfer efficiency tests > all consider the mass of the pot in the calculation. There may be many > others ? I have not read them all, of course. I would like to investigate > the implications of this. > > > > The work done heating the water (and the pot) is measured to the boiling > point and includes heating the thermal mass of the water and the pot > together. At the very end you mention the difference in in energy being > 130,000 for the aluminum and 26,000 for the stainless steel pots. This > 104,000 Joule difference should be applied to the portion of the test that > involves changing the temperature, not the whole test because most of the > time, there is no change in temperature. > > > > The answers sought related to portions of the test, which are separately > reported (good). If we take the change in temperature to be 80? C then the > energy needed to heat the water (calculated on the same basis as the energy > needed to heat the pot) is: > > > > 5000 g x 4.186 x 80? = 1,674,400 J > > > > The pots used respectively 26,000 and 130,000 (from your calculation) > > > > Thus the two tests require 1,700,400 and 1,804,400 respectively for a > difference of 1.061 in the heating work done. This means the improved pot > was required to (and did) absorb 6.1% more heat during that portion of the > test. Once the pot is hot, the impact of the pot mass disappears because > the temperature is pretty much constant. > > > > Because the pot mass was not considered in your calculation, the > ?additional heat gained? number (the claim that all things considered, it > gains heat more efficiently) drops from 16.1% to about 10% > > > > 10/16.1 = 0.62, 1-0.62 = 0.38 = 38% under-reported performance > > > > I think recalculating it to include the pot mass would materially affect > the conclusions ? i.e. that the difference in the calculated result is > significant with a high degree of confidence. > > > > With respect to the determination of thermal efficiency at low power, > the things being measured ? missing mass of water and energy consumption ? > are not strongly correlated because, as you clearly explained, the losses > of heat from the pot by routes other than evaporating water are large > compared with the energy used for evaporating water. Very small changes in > the local circumstances strongly affect the calculated result. > > > > For this reason, there was some time ago a general agreement that > ?simmering efficiency? is not really a helpful indicator because the > calculated efficiency of a perfect simmer is 0% which is counter-intuitive > to the claim of the method applied. If you changed the low power fuel burn > rate, you will get a different low power efficiency at each power setting > because it is a method that does not actually report the low power heat > transfer efficiency (or the fuel efficiency). > > > > I predict, based on your numbers, that if you were to test the same pots > using cold water on a low power flame, the heat gained by the finned pot > would be of a similar order of magnitude larger than the standard pot as is > shown above, i.e. the difference between 10 and 16.1. > > > > The work done by the stove in heating the water can most accurately be > measured when the water is not boiling for all the reasons you stated about > conductive, convective and radiative losses. As we are testing the pot, not > the stove or the fuel, it will be most accurate if the water and pot are > heated from some temperature above ambient such as 30? (to ensure that the > heat gain rate is continuous and stable) to about 70? above which point > some evaporation can be expected, complicating the calculation and > introducing the relative imprecision caused by a changing mass v.s. a > changing temperature. Heat gain assessed by ?T is about 500 times more > accurate than assessing it by ?M. > > > > The presence of a lid ensures that the heat gained is collected and not > lost to radiation or small amounts of water evaporating. The result, the > temperature rise of a 20? pot from 30? to 70?, is a very good reflection of > the gained by the pot and virtually eliminates errors. > > > > I would be really interested to see the difference between these two > methods reported for that very same pot, taking your set of experiments as > a baseline. I predict that the improvement in heat gain, calculated from > 30? to 70? and taking into consideration the pot material and mass, will > show an improvement of about 16% for a steady state fire of any magnitude > that you used. > > > > Where my estimate will be wrong is the low power comparison because the > baseline is not really a measure of heat transfer efficiency, but my > estimate not it will not be as wrong as the baseline number. > > > > As the finned pot is claimed to be for cooking with gas (as I understand > it) only two need be need be performed for high and again for low power > (one for each pot type). > > > > Because the heat transfer efficiency is not dependent on the mass of > water in the pot, the water does not need to be exactly 5000 g if the pot > mass is considered. This is important for testers to realise. This > mass-independence was recently confirmed again by students at the China > Agricultural University to a high degree of precision (four nines) across a > wide range of ?pot fullness?. > > > > I find this knowledge really helpful for comparing stoves that do not > deal well with such a large pot. Putting in 4 litres of 5, or 6 would not > change the calculated heat transfer efficiency because it doesn?t > measurably vary. But the pot mass must be considered if there is a change > in water temperature. > > > > If there are other experimenters in Stove Land who have finned pots it > would be great to hear from them as well, comparing not only the different > appliances, but the different calculation methods. > > > > Best regards > > Crispin > > > > > > A few months ago we had a discussion of Cajun Rocket Pots, a series of > pots with heat transfer fins on the bottom meant for cooking seafood in the > Southern US. Their claim was that their pots reduce fuel use by 50% and > reduce time to boil considerably. (The name ?Rocket Pot? has nothing to do > with the rocket stove.) I gave the opinion that their design was excellent > and that it would revolutionize our cookstove work. All we had to do was > test it on some stoves of the type we use and confirm that it works. > > > > Alas, reality interfered. I got one of their pots, the 8 quart size. > This is their smallest size and is appropriate for a 5 liter water boiling > test. The finned pot performed only marginally better than a regular pot > of the same size, typically by about 10%. Very disappointing. It?s > possible that for certain types of stoves with certain shapes of gas > burners the pot really does perform well, but it did not perform > particularly well on any of the stoves I tested. > > > > I?ve attached a report with the test details of a finned and a regular > pot being tested on 7 different stoves. Some stoves gave better results > than others, but the 10% improvement is a typical number. > > > > Dale Andreatta > > <Cajun Rocket Pot > Report.pdf>_______________________________________________ > > Stoves mailing list > > > > to Send a Message to the list, use the email address > > [email protected] > > > > to UNSUBSCRIBE or Change your List Settings use the web page > > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org > > > > for more Biomass Cooking Stoves, News and Information see our web site: > > http://stoves.bioenergylists.org/ > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20131118/33d78ce6/attachment-0001.html > > > > ------------------------------ > > Message: 2 > Date: Tue, 19 Nov 2013 09:48:28 +0300 > From: Cookswell Jikos <[email protected]> > To: Discussion of biomass cooking stoves > <[email protected]>, [email protected], > Global > Alliance for Clean Cookstoves <[email protected]> > Subject: [Stoves] Household Burns from cookstoves. > Message-ID: > < > caa-40hlpx_5tydklhxcdoi76ihtxreoyush5tcyk086+lux...@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Dear all, > > I was contacted by my friend Ferny who does amazing work at local Kenyan > hospitals, she is very concerned about the number of children coming in > with serious burns from the cookstoves. > > Here is part of the email in which we were discussing this: > "I have a question or rather suggestion. Can you or maybe you know of > someone, think about the following.I initiated a project 7 years ago to > entertain kids in hospitals with clowning, puppetry, storytelling music > etc. We work in 10 locations. We see a lot of children with severe burns, > like really bad almost 50% of their body, from falling in hot sufuria's. > Can someone think of some sort of safety device, a frame to put around or > anything to protect the kids from falling in. Maybe you could even get > funding for this so that people don't need to spend a lot of money buying > it. I don't know if there is a market, I am only thinking out loud to > prevent the kids from getting burned. And maybe you have nothing with this > then that is also fine. I am just concerned and thought maybe someone can > have a very good idea....juts a thought. And maybe you can get some > business out of it, or if someone wants to sponsor it. Would love to hear > your thoughts. have a great day salaams,Ferny > www.sarakasihospitalproject.org"" > > Please let us know if anyone has any ideas about saftey systems for stoves. > > I feel that perhaps it could also be alot of social issues surrounding > this, i.e. working mom's whose eldest children cook for the rest, lack of > kitchen saftey training etc. > > > Many thanks in advance. > > 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 > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20131119/07ca50d7/attachment-0001.html > > > > ------------------------------ > > Message: 3 > Date: Tue, 19 Nov 2013 16:46:29 +0800 > From: Joshua Guinto <[email protected]> > To: Discussion of biomass cooking stoves > <[email protected]> > Subject: Re: [Stoves] In search for a stove model for the disaster in > the Philippines > Message-ID: > <CABxLnO2JVzb6w5c4F89uW9b6ffwM1gbJPO= > [email protected]> > Content-Type: text/plain; charset="iso-8859-1" > > Dear All > > First of all, i would like to thank everyone who pitched in their ideas, > references and support in my search for the stove model best fitted to the > scenarios in the Philippines after the Typhoon Haiyan. To mention a few.... > a new TLUD stove model from Dr. Paul Anderson, the Estufa Finca from Art > Donelly, the brick institutional rocket stove from Jon, Larry and others, > the Siliver Fire Stove, the charcoal stove from Gustavo, the Jompy Water > Boiler and all the rest that i might have failed to mention. I thank you > all. > > Now that i received some initial fund from a friend, i was able to buy the > plane ticket. Tonight, i leave for Manila from here at my home town and > then tommorow noon, i will be in Cebu. the first stop is to meet a circle > of supporters there and evaluate and organize a pilot manufacturing outfit. > We will see, which stove model we can quickly manufacture and hopefully, on > the third day, i can already bring to Tacloban for actual tests at the > evacuation center. I may have to jump back and forth between the > manufacturing and the actual stove use several times. I will see how it > goes. > > Along with the stoves, i will be working on water filters, rain water > collectors, container gardening (which is why the biochar making component > of the stove is very important) and even toys for the children. There is > much yet that i do not know so every thing is pretty un structured as this > moment. > > Will tell you more news in a few days. > > Good day to all > > Jed > Philppines > To Cebu and Tacloban > > > > > > > > 2013/11/16 [email protected] <[email protected]> > > > On 11 Nov 2013 at 12:00, [email protected] wrote: > > > > > Tin canium Rocket stoves with say ash insulation would be cheap and > > > fast but no charcoal. > > > > My experience of doing that is that the tin can burnt through after about > > 3 firings, but uninsulated will last much longer and still be an > > effective stove. > > > > It is also perfectly possible to obtain some char at least from a rocket, > > especially if the stove is extinguished after use by removing unburnt > > wood and snuffing it in a tin with a lid along with all the remaining > > char. My StoveTech rocket can actually liberate similar amounts, > > sometimes more char that way then my Reed TLUDs, and mine is not even the > > char making version. > > > > Not so relevant in the Phillipines right now, but by using an old kettle > > BBQ as a fire bowl with the bottom half filled with earth, after the fire > > has died down, by placing the lid on and sealing the little vent with > > earth this liberates a bucket full of char. > > > > Neil T > > > > _______________________________________________ > > Stoves mailing list > > > > to Send a Message to the list, use the email address > > [email protected] > > > > to UNSUBSCRIBE or Change your List Settings use the web page > > > > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org > > > > for more Biomass Cooking Stoves, News and Information see our web site: > > http://stoves.bioenergylists.org/ > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20131119/f1298856/attachment-0001.html > > > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org > > > for more Biomass Cooking Stoves, News and Information see our web site: > http://www.bioenergylists.org/ > > > ------------------------------ > > End of Stoves Digest, Vol 39, Issue 21 > ************************************** > -- Chinese agriculture technology network pays tribute to the global peers!
_______________________________________________ Stoves mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://stoves.bioenergylists.org/
