17. of August 2016
The absolute amount of water per volume unit of gas at ~atmospheric pressure sets the dew point. (temperature)
We cannot condense out any water without going to or below that dewpoint (temperature).
Hot woodgas, as leaving the grate has about 25% relative humidity (water, steam) in it.
When cooled down, it shrinks (by volume) and the relative humidity rises.
When cooled enough, the relative humidity rises, approaching 100% .
Reaching 100% relative humidity is reaching the dewpoint.
From there on, with further cooling, the dew point is “pushed” further down, and producing condense = water.
The relative humidity cannot go over 100% ; satisfied is satified!
After dropping out the “over satisfaction at 100%”, the relative gas humidity stays at 100% if no change in pressure or temperature happens.
From here on, we can dry the gas by rising its temperature.
As a foggy morning clears up by the heat of the sun.
At the same time the gas starts expanding…
This makes it possible to final-filter the gas in a dry paper filter… the paper needs lower relative humidity.
The heat transport from the gasifier to the cooler is (under normal conditions) a straight function of the motor’s gas consumption.
Therefore, the gasflow determines the cooling surface needed.
The cooling starts immediately after the grate!
So: Liter X thousans of RPM X 3
l X n X 3 = gas consumption
As before, is the gas consumtion.
Cooler area = l X n X 0,5–0,8 = m2