Air flow requirements per stove size

[scottiniowa]

Has it been calculated or discussed (on this forum board, if so just point me in the right direction), the required airflow to make any particular size unit work properly? Simply said, lets say a 6" Batch box unit, needs X amount of airflow based on Cubic feet per minute or other volume measure. And then this figure for 8" and so on.



This question come about, as per a local discussion, that a free standing, short chimney unit in a somewhat drafty, not tight house, could allow LOTS of air pass through the fire and out the flue, vs one in a tight house with a properly sized flue, (restricted air available, not restricted flue)



Figured someone would know. We are looking for actual numbers, not, "It works best to crack the window open, ideas on this" AS some of the modern houses, can fairly well calculate air infiltration or availability.

thanks in advance. 

[fiedia]

I did some air flow measurements on a 5’’ batch rocket. Below are 3 examples.

Run 1: a typical run

air speed is around 4m/s. inlet cross section is 0.0045 m². Air flow around 0.018 m³/s (64m3/h or 38ft3/mn).



Run 2: slow burning fire.
air speed is around 3m/s. Air flow around 0.014 m³/s (50m3/h or 30ft3/mn).


Run 3: fast burning fire.
air speed is reaches 6m/s. Air flow around 0.028 m³/s (100m3/h or 60ft3/mn).

The beginning at 2m/s is smoky. I guess there was some wood too close to the HR port. I had to pack the wood load to get a cleaner fire.

The values given here are not much accurate. I did not calibrate my anemometer and I assumed laminar flow in the wind tunnel where it is placed. I did some cross checking with the energy balance between wood weight and air flow temperatures. I guess the wind measurements are accurate within 30 to 50 % (15 to 120 ft3/mn!).

It gives some numbers for a 5’’ batch rocket. If you want to scales it for 6’’ and bigger, my guess is that Air flow x Burn duration is proportional to Wood load. It comes from energy balance. So if you get wood load weight and burn duration from other batch rockets, you may be able to scale up the 5’’ results.

[scottiniowa]

wow, Fiedia, that is some serious number crunching...and should put me in the ball part of the main question, thank you.
Scott