Clean Combustion Needs More Than Just Heat

We have been having a lot of fun doing a modern literature search: Surfing YouTube. YouTube is often years ahead of the slower, but probably more accurate, information in peer reviewed journal articles. I suppose that many people are looking at both.

A shared misunderstanding seems to be that making the combustion zone hotter cleans up combustion. Yes, it is great to keep the temperatures around 900°C, which shortens the residence time needed to burn up the wood gas. However, just raising the temperature misses other necessary components that also move stoves closer to complete combustion. They are:

1. FUEL/AIR RATIOS: Fuel and air are needed for complete combustion.

2. MOISTURE: Biomass has to be relatively dry to burn.

3. MIXING: Turbulence needs to completely mix the fire, air and wood gas.

4. RESIDENCE TIME: Less time is required at higher temperatures to burn up the wood gas.

5. TEMPERATURE: Good – higher temperatures decrease the residence time. Bad –higher temperatures increase the rate of reactions possibly producing more wood gas than can be cleanly combusted.

6. METERING: As Dr. Winiarski wrote in his Rocket Design Principles: “Only make the amount of wood gas that can be combusted.”