[Stoves] Understanding TLUDs, MPF and more. (was Re: Bangladesh TLUD )

[Crispin Pemberton-Pigott]

Dear Paul

I am surprised by the description of charcoal combustion offered below. If you hold that a TLUD is making a combustible gas then burning it separately, would you not also apply this same definition to charcoal?

A charcoal gasifier, such as that produced by YDD in Yogyakarta, is a TLUD that makes CO. A charcoal burner might make gas first and might now. Carbon will go directly to CO2 on the surface of the char above 400 C with a probability of about 6/7. The other 1/7 it goes to CO.

A bottom-lit updraft charcoal fire like a BBQ is fundamentally different from a charcoal gasifying TLUD making CO, don’t you agree?

Thanks
Crispin


From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Paul Anderson
Sent: 12-Dec-17 08:07
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
Subject: Re: [Stoves] Understanding TLUDs, MPF and more. (was Re: Bangladesh TLUD )

Dear Scott and Todd,       (another of 3 replies to about a dozen messages on this topic.  Not in any special order.  I thank everyone for their comments.)

The essence of TLUD operations is the pyrolysis stage.  Stoves that are true TLUDs and THEN continue to consume the char (which is called "char gasification") will end up with only ash.  They were operated in two ombustion modes (first was TLUD pyrolysis, and second was charcoal burning).  Those could be valid as stoves, but the second mode should be noted, and not simply called TLUD only stoves.

The other type of stove is the "fan jet" or high vortex  stoves like the Philips /ACE, which are designed to push plenty of secondary air downward onto the top of the created char, with the result of very little char production.   I prefer to not call them TLUD stoves, and instead use a name that is appropriate to recognize the distinctive way those stoves work, which may be more desireable to some people.  Why call it a TLUD and not take credit for the powerful fan features?

Todd might specifically identify which stoves he is mentioning.  [That would be a very appropriate discussion of the stoves that he is able to provide to interested people.   And DO include the prices.]

Ron's comments about the 3 main ways of handling the char (his message dated 10 Dec) is well stated. (He asked for my opinion.)

Paul


Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD

Email:  psanders at ilstu.edu<mailto:psanders at ilstu.edu>

Skype:   paultlud    Phone: +1-309-452-7072

Website:  www.drtlud.com<https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.drtlud.com&data=02%7C01%7C%7C6fd7255756764eba5e3908d54105804a%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636486414232512073&sdata=OugKAl%2BAmoXbvfooVGjZ20b4q2VIOeOuf9ph4Bb129c%3D&reserved=0>
On 12/10/2017 2:25 PM, Scott Zager wrote:
Thank you for helping a novice along.  Todd has help clarify that there are many types of TLUDs.  Are they all intended to be gasifiers with a secondary combustion chamber or collection tank for wood-gas? Is it still pyrolysis if the stove combusts char to ash?  Perhaps I should continue reading the literature.  Thanks again for your patient assistance.

Scott Zager

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Todd Albi
Sent: Sunday, December 10, 2017 1:05 PM
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org><mailto:stoves at lists.bioenergylists.org>
Subject: Re: [Stoves] Understanding TLUDs, MPF and more. (was Re: Bangladesh TLUD )

Scott:

Different TLUD stoves are designed to accomplish different tasks.  There are TLUDs  designed for different tasks.  Char production will differs considerably from one design to another.  Many high efficiency TLUDs designed for wok cooking produce minimal, if any char.  There are lots of fan assisted TLUDs and natural draft TLUDs, designed for cooking that produce minimal char, only minimal fine ash. Therefore your glossary is incorrect leading off with the statement TLUDs automatically make char would be incorrect for many TLUDs that are designed for cooking.  Although there a number of natural draft cooking TLUDs designs too, that the definition maybe be somewhat accurate for.  Our organization has several TLUDs designed for cooking that produce only a thimble full of fine ash after cooking.  Those cooking implements obviously would no value for a stover, who sits on the bio char production interest side of the fence.

Many of the stove designs on this list have variable design advantages, disadvantages, depending on desired performance outcomes of stove design.   I'd contend more complicated combination cooking and thermal siphon heating stove designs, typically compact stove designs with fans, large combustion chambers, and water tanks, would not be viable transferring heat into larger volumes of water (high mass), if designed to produced char at the same time.  Large volumes of char would impede ventilation and heat transfer, that is required to maximize heat transfer into the water.  Heating the water would be the greater energy task,  to reach the desired goal of thermal siphoning in this simplified example.  In this type of stove, char production would reduce stove thermal efficiency required to maximize heat transfer to the water tank.

Regards,

Todd Albi, SilverFire



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