[Stoves] Trying new burner for TLUD's
Paul Taylor
potaylor at bigpond.com
Fri Aug 29 14:36:08 CDT 2014
HI Paul:
I am not understanding what you want to say in your point 5 below.
As far as I can see they did chimney D of 47, 63 and 100% of stove D.
They did concentrator D of like 17, 37, 70 and 100% stove D.
They note that concentrator D = 0.7 stove D generates same burn rate as
1.0D.
They note that a chimney D = 0.63 stove D (close to 0.7D) has a burn rate
only 10% less than 1.0D.
Conclusion minor obstructions have little impact on burn rate, presumably
allowing room to have a concentrator which can optimize emissions reduction,
but I don¹t think that optimum was tested.
Good work raising questions still to be answered!
I haven¹t seen where they extrapolated 0.63 to 0.7 or any data sets of 0.5
and 0.7D in either chimney or concentrator sizes, if that is what your point
5 is referring to.
Its too bad they didn¹t do a chimney height of 0.5D, but it seems the fire
power would be down and emissions up, requiring either a higher chimney as
they explored or a more efficient combustor as Kirk explored and found.
If culture demands the short height, then Kirk-like combustor or fan forcing
seems to be needed.
Paul
On 8/29/14, 11:26 AM, "Paul Anderson" <psanders at ilstu.edu> wrote:
>
> Marc and all,
>
> I am glad that we have the Brizer et al paper.
>>
>>
>>
>>
>> Birzer, C; Medwell, P; Wilkey, J; West, T; Higgins, M; MacFarlane, G; Read,
>> M. 2013. An analysis of combustion from a top-lit up-draft (TLUD)
>> cookstove. Journal of Humanitarian Engineering, 2(1).
>>
>> http://www.ewb.org.au/jhe/index.php/jhe/article/view/11
>>
>>
>>
>>
> It shows some serious testing. As a course project, these students did
> better measurements than so many other more-casual examinations of TLUD
> stoves.
>
> However, there are some differences between the academic and the practical
> aspects. I am making observations, not criticisms or compliments: [Also,
> if I have missed some point or incorrectly cited something, please excuse me
> for replying after only a quick re-reading.]
>
> 1. The experimental TLUD was a single walled fuel canister. (not what is
> being made in TLUD projects, with double walls.)
>
> 2. The diameter is 200 mm (D = 8 inches), which is also uncommonly large.
>
> 3. The study of chimney heights were with chimneys equal to very close to D
> [8"] and 1.5 x D [12 inches] and 2 x D [16 inches]. Interesting results.
> But there are no TLUDs that use RISERS or Pre-pot chimneys greater than 0.5
> x D. So the results are interesting, but are not related to the practical
> aspects of making TLUDs for household usage.
>
> 4. A tall chimney can favorably impact the clean combustion of the gases
> even if there is no concentrator. The other extreme, being NO chimney, will
> be results of burning the gases at will at the top of an open fuel chamber,
> and that will be with poor emissions. Adding a concentrator with a short
> chimney has a chance to have better (lower) emissions.
>
> 5. I question whether or not 0.63 x D should be rounded up to 0.7 or
> rounded down to 0.6. Just an observation. But the difference between 0.47
> and 0.63 is not as noteworthy as between 0.5 and 0.7 when explaining the
> rather large difference in results between the two sets of data and comparing
> to the 1.0 data set that is similar to the 0.63 data set.
>
> I met these Australian researchers when they, while still students, attend
> the CHAB Camp conducted by myself and Hugh McLaughlin and Paul Taylor (in
> 2010). Great guys, eager learners, keen to run experiments, and they
> completed what they set out to do. I again say Congratulations. And Thank
> You.
>
> But they were doing just the start of what is needed, and what could be done
> in university courses, and by the rest of us. To over rely on their results
> and methods should not be the basis for advancing TLUD (or any other)
> technology. Replicate, alter, advance, and replicate again.
>
> 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 <http://www.drtlud.com>
> On 8/29/2014 11:51 AM, Marquitusus wrote:
>
>
>>
>> Dear Paul and others,
>>
>> Thanks for your comments.
>>
>> If you think the 0.7 diameter hole is not correct, what about the other
>> conclusions of this paper? for example, it says that "the optimal chimney
>> height is seen to be at 1,5D and a with of D" (D = diameter of the burning
>> chamber)
>>
>> Marc
>>
>>
>>
>>
>> Date: Fri, 29 Aug 2014 10:00:21 +0800
>> From: crispinpigott at outlook.com
>> To: stoves at lists.bioenergylists.org
>> Subject: Re: [Stoves] Trying new burner for TLUD's
>>
>>
>> "Anyone knows any other works on this aspect"
>>
>>
>>
>>
>> (circle of flame)
>>
>>
>>
>>
>> Dear Paul
>>
>>
>>
>> I think that is exactly what Gus was doing. We had a discussion about it a
>> couple of months ago.
>>
>>
>>
>>
>> Regards
>>
>> Crispin testing cooking stoves with short chimneys - will report...
>>
>>
>>
>> Dear Marc, Julien, and all Stovers,
>>
>> There has been some good discussion (and hands-on work) about the combustor
>> on the TLUDs. Here are some miscellaneous comments.
>>
>> 1. Marc wrote:
>>
>>> (the paper says that the hole of the concentrator ring should be 70% of
>>> combustion chamber diameter. In terms of area, it means about 50% combustion
>>> chamber area)
>> I think that is mis-stated. Most concentrators holes are about half of the
>> diameter of the full ring (fuel chamber diameter). For 6 inch diameter fuel
>> chambers, the size most used for holes is 3 inch diameter (plus or minus half
>> inch is fine). That hole is only 25% of the area of the whole disk. Dean
>> Still (at Stove Camp) said that his is with a 4" dia chamber has a 2" hole
>> (if I remember correctly).
>>
>> 2. Marc also wrote:
>>
>>> I never liked (for cooking purposes) the single-thick flame that comes out
>>> of the concentrator ring that use most of the TLUD's designs, because you
>>> get a narrow over-heated spot in the bottom of the cooking pot, and in a
>>> result of that, you don't get a good heat distribution in the pot.
>>>
>>> I made a new "diffuser" burner, which gives a circular flame area, instead
>>> of a single one.
>>>
>>> http://youtu.be/mhl6tt2A4T0
>>>
>>>
>>>
>>> Anyone knows any other works on this aspect?
>>>
>>
>> The use of an annulus (ring) of gases for combustion (vs. the central flame
>> of concentrators) was in the very first item ever written about what is now
>> known as TLUD stoves. See:
>>
>>
>> http://www.drtlud.com/wp-content/uploads/2013/12/woodgas-stove-reed-larson-19
>> 96.pdf
>>
>> And that stove has difficulties with maintaining flame around the entire
>> annulus when the supply of gases is not high. What I think I have been
>> reading by the recent researchers is to have something like a concentrator
>> and then an annulus, ALL below the pot. I hope that can help solve the
>> issues.
>>
>> 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 <http://www.drtlud.com>
>> On 8/25/2014 2:04 AM, Marquitusus wrote:
>>
>>
>>>
>>> Hi Julien,
>>>
>>>
>>>
>>> Thank you for the info. and the paper.
>>>
>>>
>>>
>>>
>>> Yesterday I was applying all this information to my new burner design. I
>>> realized that, according to this paper, the holes should be bigger if I
>>> wanted not to reduce the draft. I assumed my new burner act as the typical
>>> "concentrator ring", and make its empty area to be the same size as the
>>> paper recommends (the paper says that the hole of the concentrator ring
>>> should be 70% of combustion chamber diameter. In terms of area, it means
>>> about 50% combustion chamber area)
>>>
>>>
>>>
>>>
>>> What I can say since now, regarding the firsts test with this new burner, is
>>> that apart from the distribution effect, it mantains the mixing effect
>>> (pyrogas+secondary air) of the classical concentrator ring. I have observed
>>> that the flames coming out of the secondary air entrance holes, tend to
>>> concentrate in the center of the burner, just in the bottom of the area wich
>>> is not open. Then they make a spin movement, and finally find its way
>>> through the empy areas.
>>>
>>>
>>>
>>>
>>> I suppose this movements in the bottom part of the burner, very near the
>>> base of the flames, contribute to the mixing process. But, as you say, I
>>> haven't tried it under difficult conditions, so I cannot say it would be
>>> desirable in all conditions.
>>>
>>>
>>>
>>>
>>> Following your thoughts, I also think we should have to find the optimal
>>> distance between the ring and the secondary air intake. In this sense, I
>>> think that it should be desirable to mantain this distance as short as
>>> possible, in order to not losing heat through the sides. If we put a long
>>> mixing/expanding tube (chimney), we will have a very large emitting heat
>>> area. If we find there is no alternative, then we'll have to think about
>>> insulating all this area. That is the reason why I try to mantain chimneys
>>> as short as possible. What do you think about it?
>>>
>>>
>>>
>>>
>>> All the best,
>>>
>>> Marc
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Date: Sun, 24 Aug 2014 09:56:59 -0400
>>> From: winter.julien at gmail.com <mailto:winter.julien at gmail.com>
>>> To: stoves at lists.bioenergylists.org
>>> <mailto:stoves at lists.bioenergylists.org>
>>> Subject: [Stoves] Trying new burner for TLUD's
>>>
>>>
>>>
>>> Hi Marquitusus;
>>>
>>>
>>>
>>>
>>> Your burner looks like an interesting idea. It is worth checking to see if
>>> it will operate under difficult conditions, such as low pyrogas production
>>> from fuel > 12% (wet wt.) moisture.
>>>
>>>
>>>
>>>
>>> I have been testing various options such as annular rings for pyrogas,
>>> concentrator disks (not rings cf. Anderson and Wendelbo), and swirls. The
>>> problems with burners emerge with the fuel I described above. What I find
>>> is that (1) objects over the top of the TLUD reactor that prevent secondary
>>> air descending toward the fuel bed, and (2) swirls generated near the base
>>> of the gas flame, don't work well under difficult TLUD operating conditions.
>>> I am going to post the results of experiments on these shortly.
>>>
>>>
>>>
>>>
>>> The conclusion I have reached (for the burners I have tested) is that it is
>>> best not to interfere too much with the bottom of the gas flame.
>>>
>>>
>>>
>>>
>>> However, once the gas fame is well established, modifying it higher up in
>>> the burner to create turbulence or spread the flame could be a good idea.
>>> Therefore, I think your idea has merit. If you haven't already done so,
>>> you may want to experiment with the distance your disk is above the
>>> secondary air intake, i.e. is there sufficient space for the gas flame to
>>> expand.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Based on the work by
>>>
>>>
>>>
>>>
>>> Birzer, C; Medwell, P; Wilkey, J; West, T; Higgins, M; MacFarlane, G; Read,
>>> M. 2013. An analysis of combustion from a top-lit up-draft (TLUD)
>>> cookstove. Journal of Humanitarian Engineering, 2(1).
>>>
>>> http://www.ewb.org.au/jhe/index.php/jhe/article/view/11
>>>
>>>
>>>
>>>
>>> you should check to see that the size of your disk, relative to the burner
>>> outer diameter, doesn't slow down the TLUD reaction too much.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> All the best,
>>>
>>> Julien.
>>>
>>> --
>>>
>>>
>>> Julien Winter
>>> Cobourg, ON, CANADA
>>>
>>>
>>>
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>>
>>
>>
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>
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