Tuesday, February 15, 2011

What Happens When Wood Burns? Article 2 of 3

This is the second of three articles on the above subject.

1. Evaporation of water. Posted 2/11/11

2. The emission of smoke.

3. The charcoal phase. To be posted 2/18/11

The emission of smoke:

As the wood heats up above the boiling point of water, it starts to smoke. The smoke is visible result of the decomposition of the solid wood as it vaporizes into a cloud of combustible gases and tar droplets.

The smoke will burn if the temperature is high enough and oxygen is present. When the smoke burns, it produces the bright red flames that are characteristic of wood combustion.

If smoke does not burn in the firebox, it will exit the appliance and into the chimney where it will either condense forming creosote deposits or be expelled as air pollution. Unburned smoke represents an efficiency loss because it contains a large part of the total energy in the wood.

However, catalytic stoves with the use of a catalytic combustor, burns this smoke before it is expelled as air pollution and burns it as a fuel to produce heat that can be 2-3 times hotter than the firebox temperature. This also gives a higher efficiency out of the stove.

At the same time, the catalytic combustor will burn up to 90% of the creosote contained in the smoke. (Read more about this in earlier articles I have posted)

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