[Stoves] TLUD gas mixing

[Harris, Kirk]

Ron,

Thank you for your interest, questions, and your patients with my 
odd-ball ideas.

I have added a bit to my answers to your questions. Attached is a 
hypothetical model which might be interesting and help communicate why 
the bluff body burner works so well.

Kirk

On 7/17/2023 6:48 PM, Harris, Kirk wrote:
>
> Ron,
>
> Thank you for the response and questions.  I put the paper on the 
> stoves list thinking that it would not be pertinent on the biochar list.
>
> Have you found any equations to give the pressure changes you want?
>
> The only math that I am capable of is simple, and for building simple 
> stoves designed from experience. An engineer or mathematician could 
> probably use this system to build a coputer model.
>
> How did you pick the small cone angle fand diameter) for the two bluff 
> bodies? They are both from experience. The cone angle resulted from 
> trying different angles. If the angle is too flat and the bluff body 
> becomes tilted, then the gas all goes to one side forming an uneven 
> flame. If the angle is to steep, the outer edge is too high, reducing 
> the burn time. 7 or 8 degrees works well, and is forgiving if tilted. 
> The diameters began at the same diameter as the fuel reactor chamber. 
> I found nothing that works better, except perhaps a little bit larger 
> on the upper bluff body. Too small does not get enough increase in gas 
> velocity or surface contact with the secondary air, and too large 
> creates too much flow resistance, hurting the stove function. The 
> height of the bluff body above the concentrator ring depends on the 
> intended power level to be used. More space for higher power levels. 
> For moderate power levels the point of the cone should be about 
> 1/4"(6mm) above the concentrator. Same opening size question for the 
> two concentrating rings?
> The concentrator ring on the fuel chamber is a size that worked well with turn-down to low power, and also works with very high power levels.  The upper ring works well in a range from the same diameter as the lower ring, up to the diameter of the bluff body.Without the concentrator on the fuel reactor chamber, the efficency is 
> slightly lower.
>
> If you had added a swirl component to get a longer path length, might 
> that have been worth the extra cost and complexity? Or are you pretty 
> sure (from your measurements at Aprovecho you have very minimum 
> exiting combustible gas? (Or enough exiting Oxygen?)
> I have considered swirl to provide more dwell time.  Note the inward and outward movement of the flame already gives extra dwell time.  I don't think swirl is needed as the emissions are very clean.
>
> Kirk H.
>
>
> On 7/16/2023 9:50 AM, Ronal Larson wrote:
>> Kirk and stoves list;  adding biochar.io for the many who may be flaring their syngas.
>>
>> 	Another great stove message.  Thanks.  (To others - Kirk and I have been discussing this topic for about 20 years (before the word “biochar”)
>>
>> 	I’m pretty sure this could be analyzed with different thermo models relatively easily -  because it is 2-D (nothing happening in rotational direction.  There could be a Masters or Doctoral thesis in here..
>>
>> 	Have you found any equations to give the pressure changes you want?
>>
>> 	 How did you pick the small cone angle fand diameter) for the two bluff bodies?
>>
>> 	Same opening size question for the two concentrating rings?
>>
>> 	If you had added a swirl component to get a longer path length, might that have been worth the extra cost and complexity? Or are you pretty sure (from your measurements at Aprovecho you have very minimum exiting combustible gas?  (Or enough exiting Oxygen?)
>>
>> Ron
>>
>>
>>> On Jul 15, 2023, at 12:51 PM, Harris, Kirk<gkharris316 at comcast.net>  wrote:
>>>
>>> Hi All,
>>>
>>> Attached is a document showing some interesting things I have been working on.  A stove with the single specialized bluff body tested exceptionally clean at Aprovecho (6-23-23).  Perhaps not of any use, but maybe interesting to some.
>>>
>>> Kirk H.
>>>
>>>
>>> -- 
>>> This email has been checked for viruses by AVG antivirus software.
>>> www.avg.com
>>>
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