[Stoves] FW: ETHOS 2013: Where is the New Data on Stove Performance in the Field?

[Dean Still]

Dear Paul,

Did you see that a TLUD, natural draft by the way, did best in Jim Jetter's
recent tests? There's no problem testing TLUDs that I experience especially
using a bomb calorimeter to know the remaining values.

I test TLUDs frequently and am not having problems. The problem with stoves
is not in the testing. The problem is when they are not tested. Developing
the TLUD so it's both super clean and super fuel efficient happens by
testing, changing, testing.


Best,

Dean




On Fri, Dec 7, 2012 at 10:03 PM, Paul Anderson <psanders at ilstu.edu> wrote:

>  Crispin and all,
>
> With the exception of one point and one wording, I can agree with
> Crispin's comments and I hope others also find these observations and
> dialogues helpful.
>
> One wording problem:
> ****
>
> Paul wrote:  >
> Just please do not have testing that poisons the waterhole for those who
> are working with TLUD and other micro-gasifier stoves.****
>
> Crispin replied:
> Well, that is well put. The current WBT calculations do exactly that.
> There are several ‘fatal flaws’ which means the final number(s)
> misrepresent the true performance of the product. Some stoves are
> accidentally ‘optimised’ to perform well on a given test but this does not
> improve their actual performance when viewed through the lens of a more
> rigorous test.****
>
>
>  Comment:   "The current WBT calculations do exactly that."   refers to my
> sentence that included the "not".   So I think that Crispin  is saying that
> the current WBT actually DOES poison the waterhole.
>
> One exception (or in need of clarification by Crispin).   I leave below
> the entirety of "Item 3" so that it is not out of context, but my point is
> this:
>
> With a good solid fuel and a sufficiently large TLUD (like the Quad TLUD),
> you only need ONE fueling of the batch to complete BOTH the boiling and
> simmering parts of a complete WBT.   So if the unit is loaded with fuel
> that would continue to pyrolyze AFTER the completion of the test, that
> would mean that UNNECESSARY fuel is being charged as part of the Fuel
> efficiency (fuel consumption).    And that was clearly the case in the 3
> test runs of the Quad stove.   Look at the total time of operation of each
> batch of fuel.
>
> Note the 3 different sizes of the pieces (shown in the photos) use in the
> 3 runs.    We were learning about fuels and extending the operating time as
> well as about stove test results.   (Should not mix 2 objectives, but time
> and money are rather limited when I am paying for it all myself.)   We
> learned that we can get more fuel into the fuel chamber if the pieces are
> thicker, and that the total time will be longer (because pyrolysis to the
> center of thick pieces is longer and slower.)
>
> And believe me, the cooks seem to be much more interested in the length of
> the burning time than they are about any certified correctly-conducted
> measurements for a WBT.   I guess we Stover designers are serving two
> masters:   Those who check test results before allocating any funding, and
> those who use the stoves to cook meals.
>
> So, if the TLUD could complete the full WBT test with only 1.2 kg of fuel
> on each of the 3 test runs, then the FUEL consumption would be 1.2 kg
> instead of the 1.6 kg average that Crispin calculated from the data sheets.
>
> So, let's make sure that FUEL efficiency is related to the task of the WBT
> and not to the capacity of fuel in a batch fuel chamber.  Let's have test
> results that are clear about what is being stated.
>
> (the referenced messages are below)      Paul   (In Kampala until 17 Dec)
>
>
>
> On 12/7/2012 5:20 PM, Crispin Pemberton-Pigott wrote:
>
> ****
>
> ** Paul wrote:
> **
>
> >3.  This could imply that the stove was operated until the end of
> pyrolysis even if that was many minutes after the complete WBT was
> conducted.   ****
>
> **Crispin replied:
> **
>
> I am not making that assumption t{h]ough it is one possibility. For
> example a stove may have a fire shut-off mechanism capable of extinguishing
> the flame within a short time. I do not want to anticipate what might be
> invented. Because the nature of a test to get a particular metric requires
> the fire to be stopped at the end, it is reasonable to make a plan to do
> so. There is a method called the Burn-Out Test which was specifically
> designed to test stoves with pellet-like fuel that cannot easily be shut
> down and which in any case contain all sorts of half-burned bits of fuel.
> Dr Taylor rated that method at about 15% error.****
>
> ** **
>
> PARTIAL SOLUTION that creates havoc is that the SAME stove could be
> operated identically with the amount of fuel carefully calculated to have
> pyroylsis end within a minute after the WBT was completed.   ****
>
> ** **
>
> Although this is possible, it is not necessary. The performance of any
> task like stir-frying, water heating or fish drying can be measured in a
> couple of ways. I won’t bore you with them now.  The penalty for an
> un-extinguishable or uncontrollable fire is real. They are, after all,
> dislikeable traits.****
>
> ** **
>
> >Fill a TLUD with 3 kg of fuel for one test run, and then do it with 1 kg
> for the second test run.   ****
>
> ** **
>
> This needs to be considered. I don’t see the obvious advantage through
> this explanation.****
>
> ** **
>
> >In other words, Crispin's correct statement (that the  original loading
> of 1600 grams of wood) is NOT related to the amount of FUEL used up until
> the time of the completion of the WBT.****
>
> Actually, it is. ****
>
> ** **
>
> The test of the Quad 2 was conducted in 2 phases wherein the raw fuel was
> loaded twice (the amounts are indicated) and both burned well past the
> completion of the relevant section. The test as not completed in one go, in
> other words. The remaining fuel was discounted to obtain the fuel burned
> heat value (for getting the thermal efficiency, fire to water). The total
> raw fuel needed to conduct a complete WBT I calculated from the mass of raw
> fuel burned for each section and the char produced in that process. The
> average for the three tests was 1550 g of raw fuel with a moisture content
> of 15%.  If the stove was loaded with 1600 g it would in in all likelihood
> complete the hot start and simmer sections in one go.****
>
> ** **
> ****
>
>
> Paul S. Anderson, PhD  aka "Dr TLUD"
> Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
> Website:  www.drtlud.com
>
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