Family Stove Critical Dimensions and Calculations
1. Top of combustion chamber (CC) to top of adobe or regular brick = 2 cm. With 1.3 cm Rebar, the distance from the top of the CC to the bottom of the pot, pan, or grille = 3.3 cm
2. The gap all around between the pot and the pot skirt (PS)
1. Pot skirt
|Diameter of pot in cm||20.0||22.0||24.0||26.0|
|Gap all around||2.2||2.0||1.8||1.6|
|Diameter of pot skirt (PS)||24.4||26.0||27.6||29.2|
|Circumference of pot skirt (PS)||76.0||81.0||87.0||92.0|
|Length of pot skirt (PS)||81.0||86.0||92.0||97.0|
2. Flow calculations for a 24 cm pot, pan, or grille
Input flow A = w x h = 14 x 11.5 = 161 cm2
Output at flue pipe A = πr2 = 3.1428 x 25.8 = 81 cm2
This difference will be OK, because the area of the wood and ashes is not calculated and the stove works very well in practice.
Institutional Stove Critical Dimensions and Calculations for 40 cm Pot
(Source: Design Principles for Wood Burning Cook Stove, Aprovecho Research Center page 14)
1. Top of combustion chamber (CC) to top of adobe or regular brick = 3.7 cm
2. Between the pot and the pot skirt the gap all around for a 40 cm diameter pot is 1.5 cm
1. Pot skirt
Diameter of pot skirt = 40 + 1.5 + 1.5 = 43 cm
Circumference of pot skirt C = πD = 3.1428 x 43 = 135 cm
Add a 5 cm overlap for joining together and the sheet metal will be 140 cm long.
Therefore, make the cut 140 cm long at a width of say 13 cm. The sheet metal should be thin.
2. Flow calculations
Input flow A = w x h = 19.3 x 11.5 = 222 cm2
Output between pot skirt and 40 cm pot
Area of skirt = πr2 = 3.1428 x (43/2)2 = 1452 cm2
Area of pot = πr2 = 3.1428 x (40/2)2 = 1257 cm2
Thus inflow is greater than outflow by 222 – 195 = 27 cm2 which is OK, because no calculations are made for the area taken by the wood and coals.
If the stove is to be used indoors, then a flue pipe will need to be added and the pot skirt will need to be wider so it is above the top of the stove and crimped like the family stove. Also the pot skirt will need to be cut at the bottom where the hot gases exit to the flue pipe.