Crispin, Jim, and List See few comments below
----- Original Message ----- From: To: "Discussion of biomass cooking stoves" <[email protected]> Sent: Monday, April 22, 2013 8:47:51 AM Subject: Re: [Stoves] FW: REQUEST for complete sets of raw data of cookstove tests. Dear Jim and Anyone watching I won't have time to dig through the messages on this thread that were in limbo. If something is really important to someone, ask again. With regard to the char remaining and the wood that has been burned on one end (fuel left over from tests) Harold Annegarn and I have a proposal for how to deal with stoves that can use fuel remaining from a previous burn. In principle, the test should be started with the fuel left over from a previous test. In other words a cooking task that is replicated a number of times in which the fuel left over goes into the stove for the subsequent task provides an opportunity to measure (quite accurately) the raw fuel drawn from the pile. [RWL1: I suggest that any test has to account for stoves being used to BOTH cook AND make char . I don't sense you will concur with this variation. Or can you? I believe that forcing the reuse of char in many/most char-making stoves will not be the way the char will normally be used - and therefore will give erroneous results . Any charcoal that is not being discarded and all partially burned, dried, blackened stoves that are claimed to be useable fuel, not discarded, should be used. If new fuel is needed (which it will be) then that new fuel is raw fuel. It becomes quite a simple matter to measure how much new fuel is required for each identical replication of a task. [RWL2: I guess there may be a few cooks who "discard" char - but that is not my experience. As long as the procedures call for reporting it both ways, (as I gather from Jim Jetter remarks today) th is suggestion probably helps promote char-making stoves. Not sure what was intended above in " blackened stoves" - maybe "blackened fuel"? With char-making stoves, there needs to be consideration to fuel that was either not or only partially pyrolyzed. That material needs to be highlighted and perhaps handled as "lost energy" - similar to that not captured by the cookpot. But similarly to subtracting char energy in the denominator of an efficiency computation, this energy could be subtracted. It is certainly not lost forever. It is possibly ideal for starting the next time. It is not clear that such un-pyrolyzed material is now being handled properly, (I see no term for subtracting ths unused energy as I do for char energy - but I need to look at tha t again.). The issue is discussed in the attached document in '1. Replications'. A number of definitions are provided in the subsequent sections that are useful for discussing tests and efficiencies. Importantly, if a stove cannot use any of the fuel remaining (an example might be a TLUD wood burner that makes a high % of char) the energy in the remaining fuel cannot legitimately be counted as cooking fuel - because it can't be used in that stove for cooking. [RWL: So it s not clear what you propose n this case. I disagree if you mean to say char should count in no way at all. The stove developer intent will probably have been primarily to BOTH cook and make char. Ignoring the char then makes no sense. But repeat - I don't know what you are then recommending. ] It then becomes and easy matter to determine the raw fuel consumption per cycle for that task. [RWL: Maybe easy - but also not helpful in comparing stoves designed for more than cooking. ] [RWL: You have not mentioned adding some tests related to operator time commitments. Certainly important to most cooks. Regards Crispin -----Original Message----- To All, Resending my comment below, even though we've moved on in the conversation, because I've just learned my comment didn't post to the listserv the first time, and I wanted to make sure people know EPA is currently working on a way to share raw data - we'd be very happy to be able to share this information with the community. Jim -----Original Message----- Dear Paul, It was good to see you again in Phnom Penh, and I wish we had had more time to talk, but I hope you'll accept my invitation to visit us soon in North Carolina. I understand you believe stove testing is an extremely important issue, and we completely agree on that point! You requested raw data to help with ".finding out if results from sub-optimal earlier versions of WBT can be re-processed (processed forward) to be compatible with version 4.2.1." Our (EPA) testing in 2010 was based on Version 4.1.2. Changes made in the WBT data calculation spreadsheet between Versions 4.1.2 and 4.2.1 are documented at the web site: http://community.cleancookstoves.org/files/354 The documented changes made in the WBT calculation sheet between Versions 4.1.2 and 4.2.1 do not make any difference in results from our testing in 2010. We can discuss each change that was made in the calculation sheet, and I can explain why it doesn't affect our previous results. Changes made between versions might affect results from some other stove-testing labs. As Crispin has pointed out, one thing that would make a big difference in results is how "remaining char" is handled in the calculations, but this has not been changed in the WBT protocol or spreadsheet. Crispin and I have previously discussed this offline as well as on the stoves listserv, and I think Crispin and I agree that if remaining char is discarded in practice, then the calculations in the WBT should reflect that practice. This is an issue for the next revision of the WBT, and it would especially affect results for charcoal-producing stoves (such as charcoal-producing TLUDs). Meanwhile, we (EPA) will report future results per the current WBT protocol (energy in remaining char gets full credit in energy calculations), and we will also report results for the discarded-char scenario (energy in remaining char gets no credit). Results from our 2010 testing showed that a charcoal-producing TLUD stove burning wood-pellet fuel had very high thermal efficiency compared to all other stoves tested. But if the remaining char is discarded, the efficiency for the TLUD would be significantly lower. We haven't seen a need to report efficiency with discarded char for that TLUD prototype we tested, because that stove has not been manufactured or disseminated, but for the two TLUD-type stoves included in the ongoing round of testing, we will report results both ways - char discarded and not discarded. Back in October 2011, Crispin and I spent some good time comparing results from Crispin's proposed (for Version 4) WBT spreadsheet and our (EPA) spreadsheet - I still have the record of our email correspondence. We generally found agreement between results, and we were able to explain some minor differences in results. Rather than rehash old data now, I think it's much more productive to continue to work cooperatively together to do the challenging work ahead of us to: (1) refine existing protocols, (2) develop new protocols, as needed, and (3) build up the network of Regional Testing and Knowledge Centers. I think the Alliance (Ranyee) is doing a fine job facilitating an inclusive open process for moving forward - great discussions and progress in Phnom Penh! We (at EPA) are working hard on a process (meeting EPA QA and review requirements) that will enable us to effectively share the raw data along with results from our ongoing round of stove testing. Hope this will be helpful. Please call me if you would like to discuss this further. Sincerely, Jim _______________________________________________ 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/
_______________________________________________ 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/
