[Stoves] Bangladesh TLUD (was Re: No subsidies in TLUD char peoduction

[Nikhil Desai]

Crispin:

Did Peter Scott use WBT or CCT? Why are his findings significant except for
"competing on fuel efficiency percentages"?

What he discovered is similar to common knowledge from my childhood - in
samovars for heating bathwater. Designs with thicker copper retained heat
better and fuel efficiency was higher; which mattered because in the city
we used purchased charcoal.

Something similar from our charcoal cooking stoves - they had a cement
layer sometimes, compared to another stove that didn't.

If you standardize the cooking experience and cooking behavior, I suppose
you can adjust for the amount of heat that goes in the stove body but is
not utilized for cooking experience.

And if you were to do that, you would come up with some computation of
efficiency. Which I call "competing on fuel efficiency percentages is
infantile business" because standardizing cooking behavior and cooking
experience is infantilism.

That has nothing to do with whether fuel efficiency matters or dominates
consumer choice.

Testing and metrics ought to have a purpose. In relation to a service
standard and objective of the exercise. I compared EPA/WHO approach to
stoves with that on diesel engines. That should say a lot.

Nikhil

--------

On Sat, Dec 9, 2017 at 10:37 AM, Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:

> Dear Nikhil
>
> Competition on a fuel efficiency basis is independent of what happens
> within a stove. The statement about heat invested in the stove body is
> frequently made with the assumption that 'it is bad' to do so. This has
> been erroneously promoted by certain organisations that insist in their
> literature that the combustion chamber must be 'insulative' and have a low
> thermal mass.
>
> Well, only one of 'us' has presented a study comparing light vs heavy with
> the same design. That was Peter Scott at ETHOS some years ago. He
> discovered that contrary to the self-proclaimed wisdom of the time , that
> the heavy, non-insulative combustion chambers consistently out-performed
> the light ones by about 10% of value for the efficiency metric.
>
> So, here we have Julien discussing the thermal mass of a stove with some
> jumping in having adopted the incorrect assumption that overall, it is
> invariably worse to have heat invested in a stove body, without having
> replicated Peter's experiment.
>
> Observing that heat is invested in a stove body is a trivial exercise.
> Stating what the overall effect on performance will be is far more
> difficult. The impact is dependent on multiple factors including the
> emissivity of the outside surface, and whether there are two or more layers
> (shells).
>
> To find out which construction or material serves best, we perform
> efficiency tests and compare numbers. Optimisation is done like that.
>
> Regards
> Crispin
>
>
> Todd:
>
> Didn't you mean exclusive rather than inclusive in "It is not an
> inclusive to TLUD designs and can be adapted to any stove firebox. "?
>
> Crispin:
>
> If heat loss is insignificant, or only in relation to how it affects the
> cooking experience, and that heat is stored in the stove for later use, you
> are basically making my point that competing on fuel efficiency percentages
> is infantile business.
>
> N
>
>
>
> On Sat, Dec 9, 2017 at 8:47 AM, Crispin Pemberton-Pigott <
> crispinpigott at outlook.com> wrote:
>
>> Dear Paul and Julien
>>
>>
>>
>> I am responding to Paul’s comments on Julien’s earlier message.
>>
>>
>>
>> On Dec 7, 2017, at 6:51 AM, Paul Anderson <psanders at ilstu.edu> wrote:
>>
>>
>>
>> > 1.  The thermal mass is estracting heat, meaning cooler gases inside
>> the chamber, with risk of insufficient temperature for ignition at the top,
>> especially when nearing the end of pyrolysis.
>>
>>
>>
>> Before anyone worries about heat going into the stove body, please
>> perform the trivial calculation about *how much* heat we are talking
>> about. Just because heat goes into a stove body does not mean a) it is
>> significant, b) that it happens at a time that affects performance of the
>> cooking experience, c) that it is not returned later in the session (which
>> is cooking behaviour-dependent.) Yes, there is heat invested in the stove
>> and usually it is a loss, but the other features of the stove may not only
>> recover that heat through other energy paths, it may make the stove far
>> more accessible by being cheap and easy to make from local materials.
>>
>>
>> 2.  The concrete (or ceramic) inner cylinder does not have any of the
>> side holes (24 in the metal version).  Such holes allow for some "pilot
>> light" effect after the char level is below a hole.
>>
>>
>>
>> Dr Nurhuda’s very successful TLUD stove had such pilots sprinkled around
>> the fuel chamber. The Vesto uses three holes only, and the purpose is to
>> maintain pilot lights to ensure the flame never goes out. They are placed
>> in a way that guarantees a small portion of char is burned and there is
>> never a need to relight because of a gust of wind.
>>
>> Regards
>>
>> Crispin
>>
>>
>>
>>
>
>
>
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