Hi Crispin, Have you by any chance got any contact details of Kevin Chisholm aka Dr. Dung. I have his email add as [email protected] which was in the stovers mailing list but it apparently does not seem to work. I had questions regarding the dung washing.
Cheers Sarbagya Tuladhar Sydney On 03/07/2012, at 3:33 AM, Crispin Pemberton-Pigott wrote: > Dear Marc and Tuong > > >http://ehs.sph.berkeley.edu/krsmith/?p=249 > >It would be good to cross reference the efficiencies you found. For example, > >for an LPG stove, the report eff is only just over 50%. > Not all LPG stoves are the same of course. There is a test of an LPG stove > done using the Indian thermal efficiency test that reports a figure of about > 62% and when using the same hardware, a reasonable similar gas composition, > but at a different altitude and quite different pot, we got a figure within > 2%. > Note there is calculation error in the Indian efficiency test which is that > it does not credit as absorbed heat used to boil out water. As the range of > temperature is from 20 to 90 degrees, there is certainly some evaporation > before reaching 90 and that affects the final answer. I suggest you run such > tests in Vietnam at 30-70 degrees and then you can safely assume you will > start below 30, and not evaporate anything meaningful by 70. > In a series of tests we found that evaporation from 30-70 was within the > error of the scale readings (±0.5g) so could not be said to be detected ‘with > confidence’. > The Indian efficiency test does correctly apply the heat capacity (Cp) of the > pot taking into consideration its mass and material. This corrects a > significant error in most WBT’s, significant meaning it makes a statistically > significant difference to the final result. If you want to correctly state > the thermal efficiency <±5% the pot material needs to be considered. Ti is > not difficult to add. > The approach taken in the Indian test calculation is to calculate the water > mass equivalent of the pot the add it to the mass of water heated. This is > simple and reliable and easily understood later in the calculations. > >Also, I'm not sure reporting a single efficiency number is all that useful. > Reporting the efficiency doing ‘one thing’ using one pot at one power level, > or two power levels summed so you can’t see the difference, is not very > useful, I agree. People want to know the performance profile of a stove, not > just ‘one number’ which contains little information. If that number is not > even accurate, there is almost no information contained in it. > >The stove types you detail have much variation depending on construction > >quality, operation, fuel type, pot size, etc. > The performance of a stove varies with pot size operation method, fuel and to > a small extend, construction quality. If you interpret ‘performance’ as > ‘durability’ then that matters too and you have to report it. A stove might > fall to pieces quickly if it is operated at high power continuously, for > example. > Regards > Crispin > > _______________________________________________ > 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/ >
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