[Stoves] China study of TLUD with pellets. Was Re: Going back to 3-Stone Fire [Was Re: China and cookstoves]

[Nikhil Desai]

Paul:

I get on to my hobby horse - whatever the sequence and whatever the
protocol, "Comparing apples and oranges" is not cooking.

And fuel efficiency is but one of the attributes that makes a stove usable
and used; may not be significant when the change in fuel cost (volume x
cost, over a year) is insignificant.

A radically different technology that offers significant time savings - gas
or electricity - inspires adjustments in cooking habits, even diets.
Otherwise the cook is not much motivated to change the cooking cycle; no
matter what the lab efficiencies are, she would use the stove as she is
otherwise used to - which is not a "standard" behavior.

And when she has a choice of "stacking" - as hundreds of millions have had
over the past 100 years - fuel efficiency of a woodstove becomes even less
of a matter.

What I am trying to get at is that the "fuel savings" obsession is
misplaced, unless contextually justified with specific fuels and use
patterns. (Heating stoves have different calculus).

In turn, that "we" know next to nothing about the customers and the market,
and both keep changing.

Say, for families living in tents and straw/mud shacks, and cooking in the
open with straw and twigs in a "three stone fire", fuel savings may matter.
But their primary problem may be the cost of adequate food and they may not
want to acquire a costly portable stove to be used inside their "home".

Contrast that with a family that already has a brick/mason home with a
fixed stove indoor and possibly good ventilation. They may even have a
bicycle, beds, pots and pans, dishware. The cook there - or, if you will,
her father or husband -  may think differently of the cost (monetary or
collection) of good-quality wood.

We seem to have a fixation on certain images - popularized by stove
advocates, and now by the marketers of "health benefits" - of the cook and
her environments. I can draw several caricatures that typify implicit
assumptions that may or may not hold. (The stereotype may hold some
validity for some context and some period, and of course we would be
bombarded with one citation after another about what researchers of varying
eyesight "found" somewhere or the other sometime or the other.)

Until we have a relatively firm idea of the cook and the qualities,
diversity of fuels - just look at the India paper Ron had supplied us with
a link to - I submit the obstinacy about fuel efficiency and testing
protocols has no place (unless we are marketing to donors and not to
cooks).

All this came back to me while reading Grant's thesis - how efficiency, and
not emissions or concentrations (as proxy for exposures), drove stove
programs for decades. I also remembered kidding with Liz Bates on Grant's
Hedon discussion group - "Maggis noodles saved more trees than all improved
woodstoves combined, to date and around the world." (I exempt charcoal
stoves because the fuel and the cook are fairly uniform, with limited fuel
choice; with partial penetration by LPG - i.e., stacking - the cook may not
care that much about spending $20 on a stove if the fuel cost savings are
less than $1 a month.)

I am yet to find evidence that a higher efficiency woodstove is
mass-marketed on the basis of fuel savings alone and has any consequence
for any of the alleged ills of solid fuels. Parodies are sold for
fund-raising, that's all. There is no valid theory of large-scale change.

Of course, "Further study should be done with *different stoves* testing *a
diverse range of fuels* [to] try discover which fuel attributes and which
stove architectures combine to deliver *superior performance*."

In search of the holy grail.

Nikhil

-


On Tue, Dec 19, 2017 at 1:56 AM, Paul Anderson <psanders at ilstu.edu> wrote:

> Stovers,
>
> Sorry for my silence, but I have had 4+ days on other pressing issues.  I
> am STILL trying to catch up with messages since 16 Dec..
>
> I thank Andrew for his mostly supportive comments about "TLUD" as a  name
> with specific meaning.
>
> I have some serious questions about the Chinese research of a TLUD stove
> with pellets, referecned in Crispin's message:
>
> On 12/16/2017 2:16 AM, Crispin Pemberton-Pigott wrote:
>
> Dear Friends
>
>
>
> The paper:  https://ijabe.org/index.php/ijabe/article/viewFile/2963/pdf
> <https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fijabe.org%2Findex.php%2Fijabe%2Farticle%2FviewFile%2F2963%2Fpdf&data=02%7C01%7C%7C2ce737e1fcb04e81977608d5441d74c6%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636489815661627525&sdata=MaQEhXYbbVfEhPWeoSCl2MFqz6eRTyM3HrldZUtj2KE%3D&reserved=0> *Effects
> of biomass pellet composition on the thermal and emissions performances of
> a TLUD cooking stove* is a TLUD pellet-fueled cooking stove.
>
>
>
> Ron commented: “This achieves a record low for TLUDs of 10% efficiency -
> whereas Julien, Kirk, Paul and others are at 40% and more.”
>
>
>
> The paper reports the fuel efficiency (the energy available in the fuel
> fed into the stove v.s. cooking energy the stove delivers to the pot). The
> numbers reported by the sources, if using the WBT, are the heat transfer
> efficiency values (actually, an approximation of it – it is not exact).
> These two efficiency metrics are incompatible unless the system produces no
> residual char, which would be unusual for a solid fuel stove.
>
>
>
> Regards
>
> Crispin
>
> 1.  About the TLUD name:  Interesting that Crispin and the Chinese authors
> all say "TLUD" as if they think that such a name actually does denote a
> quite specific type of cookstove technology.   Well, that is good.   We do
> not need to be thinking of other UD-TL stoves when we read the name
> "TLUD".
>
> 2.  Three times the publication says:    "a typical Chinese household
> biomass stove without a chimney"    was selected [was tested} and fueled
> with different kinds of biomass pellet fuels.  I was not aware that a TLUD
> stove was "a *typical *Chinese household biomass stove" or that it is "a
> popular TLUD Chinese biomass stove" (Section 4. Conclusions).   Maybe
> someone could better inform us of numbers and models, etc.  Todd Albi sells
> Chinese-made TLUDs in America, so I assume some of those stoves are sold in
> China also.  But the one in the photo is not one of the models sold by
> Silverfire.us.    I would love to have a TLUD success story from China.
> But I am a bit skeptical about it being "typical" there. And  are there any
> test results (from Jim Jetter at EPA or Aprovecho or other not-in-China
> testing centers) of the stove in the cited study?   Can anyone send more
> photos?
>
> 3.  I struggle with equations and calculations (Section 2.5.1), so I
> cannot make comparative comments about the Chinese methods vs. elsewhere.
> I might be wrong, but I do not see any inclusion of the charcoal that came
> from the TLUD at the end.  That leads to some questions:
> A.  Was there no charcoal to measure?   If they run a TLUD as a charcoal
> burner stove after the pyrolysis stage is finished (and until all the
> charcoal was consumed???), that would be very inefficient and pull down the
> % efficiency calculation.
>
> B.  Or was the char just discarded as "no longer being pellet fuel" and
> therefore judged to have been "fuel used"???
>
> 4.  Section 3.2.1 says
>
> As shown in Figure 4, at the beginning of the test, the water temperature
> in the pot increased slowly. This stems from the fact that fuel with a high
> moisture content often requires additional energy to vaporize the fuel
> moisture resulting in a low net energy release rate. During this
> fuel-drying phase the emissions can be high.
>
> Interesting, this reported "fuel-drying phase"..."at the beginning of the
> test" is not like TLUD stoves that I know, where fuel drying occurs little
> by little as the MPF (decending pyrolysis zone (AJH is correct))
> progresses.   A drying phase at the beginning of a fire would occur when
> the fire is at the bottom and the initial rising heat is partially used to
> dry the fuel pile above the hot zone.      Perhaps someone can explain what
> happens in the authors' usage of their TLUD stove.
>
> 5.  The photo of the stove in operation shows what appears to me to be a
> very high-power flame.  And the Conclusions recommend
>
> Further study should be done with different stoves testing a diverse range
> of fuels [to] try discover which fuel attributes and which stove
> architectures combine to deliver superior performance.
>
> So the researchers acknowledge that "stove architectures" can be adjusted,
> implying that there was not an attempt to have the existing, typical,
> popular stove adjusted to give its best performance with three types of
> pellet fuels that were not WOOD pellets (not included in the research) but
> which might be the type of pellets for which the stove was optimized (if
> ever optimized?).
>
> 6.  Finally, in the last paragraph before the conclusions, we read:
>
> The WBT protocol, Version 4, specifies a different stove operating
> sequence [than the Chinese testing]. The EF (PMi) s dramatically different
> because of the combined effects of the very different test sequence and
> calculation method. The test sequence changes the combustion efficiency and
> combustion conditions. With its different fire management sequence, the
> combustion temperature, oxygen supply, mixing states and the differences in
> fuel evolution result in an EF (PM) that is strongly at variance  with the
> test sequence employed in this work.
>
> Well, that says much.  Comparing apples and oranges.  Perhaps others who
> are more into the details of testing might want to try to sort out what are
> the different stove operating sequences.  Perhaps BOTH are good.   Or only
> one.   or neither?   But until someone sorts that out, the fuel efficiency
> numbers cannot be compared with numbers from other testing systems.
>
> Paul
>
> Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
> Email:  psanders at ilstu.edu
> Skype:   paultlud    Phone: +1-309-452-7072 <(309)%20452-7072>
> Website:  www.drtlud.com
>
>
>
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