[Stoves] Perched Charcoal and Pilot Secondary Air

kgharris kgharris at sonic.net
Thu May 29 15:18:03 CDT 2014


  Julien and all,



  May 16 Julien proposed a way of improving the method 3 turn-down arrangement by perching char on an upper grate. I have tried this and found that it does work. I have only made it work and have not done any measurements yet to get turn down ratio. From flame size I would estimate no less than 3 to 1 and probably closer to 4 to 1. Attached is a diagram showing some observations made during the successful trial. It was the fourth trial that finally worked. This being a variation of method 3, it should probably be designated Method 3.2 or 3B. 



  During the test, one thing that I tried was to make quick adjustments from low to high and high to low. This could easily happen during field use and so it is important to know how the method responds. Method 1 has the problem that quick adjustments can blow the flame out. This method however stubbornly kept the flame going. From high to low, after a quick adjustment, the flame took about one minute to reduce to a small flame, and continued over several minutes to reduce to a very small flame. Some puffs of visible smoke came out but very little. From low to high the flame again took about a minute to enlarge to a high flame. Considerable puffs of visible smoke came out but stopped after the large flame became stable. The flame however remained alive and that is very important for field use.



  As with the other methods, it is possible for the flame be stable but be so small that the temperature cools and allows unburned aromatic hydrocarbons to exit the stove. This could be a problem since some of these hydrocarbons are toxic. A stove using this method should be designed to allow some primary air leakage into the reactor so that it cannot be adjusted this low.



  I need to continue with a wonderful idea from Dr. Larson for reducing the flame height and thus the stove height, so I will not be working on turn-down Method 3.2 or 3B for a while. I will have a demonstration of this turn-down method at stove camp at Aprovecho this July.



  Kirk

  Santa Rosa, CA. USA


  ----- Original Message ----- 
  From: Julien Winter 
  To: Kirk Harris 
  Cc: Paul Anderson ; Ronal Larson ; Crispin Pembert-Pigott 
  Sent: Friday, May 16, 2014 5:06 AM
  Subject: Perched Charcoal and Pilot Secondary Air


  Hello Kirk;


  In you work with sustaining low power rates in a TLUD you propose a "Method 3 Char-supported method"


  Instead of moving the charcoal bed upwards, would it help to keep some of the charcoal perched on an upper grate, or ring-shaped ledge grate, plus introduce a small amount of secondary air below the perch through pilot holes?


  Nice work,
  Julien

  -- 

  Julien Winter
  Cobourg, ON, CANADA
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