[Stoves] (no subject)

[Nikhil Desai]

Paul:

Thank you so much.

1. This "3Ts" is an extremely valuable acronym to convey the importance of
time, temperature and turbulence that make up performance for a particular
task (and varieties of task).

I learnt a bit about biomass gasifiers back in 1980 and then in the context
of industrial furnaces, but never quite grasped these basics of 3Ts.

I suppose my intuition that fuel quality does matter in designing a stove
for complete combustion of that fuel is broadly correct. The objective is
not complete combustion in and of itself, but with a specific fuel/stove
combination for specific tasks. With some fuel and stove designs, 3Ts are
achieved for some tasks, but with the same stove design and another fuel,
they may not be. If that is correct, "fuel-free" stove performance is
presumptively dubious.

Put another way, if the 3Ts don't come together in a way that guarantees
complete combustion (no or minuscule PICs), then that fuel/stove
combination is not appropriate for the cooking or space/water tasks desire.

I think that's a better formulation of "better biomass stove" than the
patently mindless ISO Tiers for PM2.5 hourly emission rate and fuel
efficiency.

2. I think your second answer is a practical statement of my understanding
above. That is, stove design and fuel go together, and their usability is
contextual -- because the nature of the tasks varies by context.

I never could make sense of the Aprovecho way of thinking - that there can
be "internationally acceptable" stove designs. That implied standardizing
fuel and tasks (hence the WBT experience you mention).

Let me quote a paper "Fuel use and emissions performance of fifty cooking
stoves in the laboratory and related benchmarks of performance
<http://www.sciencedirect.com/science/article/pii/S0973082610000311> Energy
for Sustainable Development, Volume 14, Issue 3, September 2010, Pages
161–171. http://dx.doi.org/10.1016/j.esd.2010.06.002.

.. The authors claim in the Abstract:


Performance of 50 different stove designs was investigated using the 2003
University of California-Berkeley (UCB) revised Water Boiling Test (WBT)
Version 3.0 to compare the fuel use, carbon monoxide (CO) and particulate
matter (PM) emissions produced. While these laboratory tests do not
necessarily predict field performance for actual cooking, t*he elimination
of variables such as fuel, tending, and moisture content, helps to isolate
and compare the technical properties of stove design*.


It stretches credulity that stove designs are tested on the basis of
excluding fuel, tending, and moisture content. This is engineering madness.
Standard fuel, standard pots, standard water, standard field conditions
(wind, humidity, temperature, ventilation. No cook.

The Lima Consensus signatories "further resolved, that *a data-driven,
long-term test protocol and standard that meet the following objectives
shall be developed within an 18-month time frame"*, such objectives to
include WHO Indoor Air Pollution guidelines that protect user health,
assuming a standard room and ventilation".

A standard room and ventilation. To me, the Lima Consensus was a sterling
example of forcing scientists of unrealistic expectations and limited
understanding into groupthink, "I can only do science if I standardize and
simplify."

But the signatories recognized that this was a TEMPORARY solution, a
beginning point of a journey together. How did TC-285 choose to ignore
that?

Thank you very much, again. You simplified and cleared up my understanding
of combustion.

Nikhil

PS: You made me seek out the book Combustion (Irving Glassman) that I had
consulted for a few pages many years ago. There are sections on soot
formation and the role of particulates in combustion that left me pretty
fascinated at the complexity of combustion.



On Thu, Jul 27, 2017 at 3:43 PM, Paul Anderson <psanders at ilstu.edu> wrote:

> Nikhil,
>
> Two replies.
>
> First, you wrote about
>
>> makes for very low emission rates independent of fuel type and quality?
>>
>

> Very low emission rates are the result of very complete combustion,
> meaning sufficient time, temperature and turbulence to get the combustibles
> to be fully combusted.   And those 3 T's are better done with air (O2)
> mixing with gases than with air swerling around pieces of solid wood, coal,
> etc, that keep cooling the processes that are trying to yield the gases.
> The creation of the gases at places at least slightly separated from where
> the gases will be burned is the distinctive mark of a GASIFIER.
>  GasifiCATION occurs in all such fires, but the SEPARATION is accomplished
> in a gasiFIER.
>
> Second, you wrote:
>
>> That a WBT can deliver "stove performance" independent of fuel quality is
>> presumptively dubious.
>>
> Amen!!!    That is why pellet-fuel (with uniform size and moisture
> content) can have an easier time to be clean burning than do many other
> biomass types.   In recent years there have been allowances for the stove
> maker to specify which fuel is to be used.
>
> I remember back in 2004 to about 2010, the testing equipment being
> established at and by Aprovecho had ONE "official fuel" so that the results
> between stoves could be compared.   Sawn kiln-dried Douglas Fir wood from a
> woodworking factory was THE fuel, and was close to perfect for Rocket
> stoves.   That requirement gave me lots of problems with tesing of the
> TLUDs.
>
> Paul
>
> Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
> Email:  psanders at ilstu.edu
> Skype:   paultlud    Phone: +1-309-452-7072
> Website:  www.drtlud.com
>
> On 7/27/2017 12:07 PM, Nikhil Desai wrote:
>
>> Crispin, Paul:
>>
>> A dumb question: Is it the production of gases or the high temperatures
>> -- or some sequence thereof -- which makes for very low emission rates
>> independent of fuel type and quality? Or is it the relatively steady power
>> requirements of a heating stove?
>>
>> It suddenly dawned on me - reading a children's book - that the type of
>> large heating stove used in Europe that also doubled for cooking was
>> because of the type of cooking: grilling, roasting, soups and stews, but
>> less of frying and spicing as in Asia.
>>
>> Or that the cuisine responded to the availability of energy delivery
>> system.
>>
>> Bernard Lewis wrote a brilliant essay called "In the Finger Zone", where
>> he said (writing from memory), "The world can be divided in three areas by
>> way of eating: fork zone, finger zone, chopstick zone. These areas are also
>> roughly fresh cream zone, sour cream (or yoghurt) zone, and no cream zone."
>>
>> Now I am thinking of world geographies and human cooking histories as
>> "Cookstove zone, Heating and cooking stoves zone, and Combo stove zone."
>>
>> I still hold that for cooking-only stoves with a rich enough menu,
>> biomass of low energy density has different emission rates according to
>> fuel quality (and operating practices, of course). That a WBT can deliver
>> "stove performance" independent of fuel quality is presumptively dubious.
>>
>> Nikhil
>
> ----------------------------
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