Dehumidification

Dehumidification takes place by cooling the air below its dew point, thereby condensing part of the water vapor contained in it.

I’ll continue the example from the previous chapter: we have a kg of air at +20°C with 60%, which contains 8.77g of water vapor (absolute humidity) .

We cool the air up to +12.01°C. Air at this temperature, with 8.77 g/kg of water vapor, is saturated, that is, has a relative humidity of 100%. This is the dew point .

We go on cooling, going below the dew point, bringing the air to +11.99°C. The relative humidity remains at 100%, but the absolute humidity has become 8.76 g/kg. We have condensed, transformed from steam to liquid, 0.1 grams of water. We have dehumidified the dry air of 0.1g.

We cool it again, this time going a bit more below the dew point, we bring the kg of air down to +2°C .

The relative humidity does not change, remaining at 100%, but the absolute humidity reaches 4.384g. We had 8.76, and 8.76 to 4.384 = 4.37. We removed from our kg of air other 4,37 g of water vapor, making condense, or making them liquid .

So, to summarize , we started with 1 kg of air at + 20°C with 60%, that is, containing 8.77 g of water vapor and having a dew point of +12.01 and we cooled to to + 2 ° C by removing 4.37 g of water vapor (making it condense). We now 1kg of air at + 2°C saturated (100% RH) containing 4.384 g of water vapor.

I’ll continue the example from the previous chapter: we have a kg of air at +20°C with 60%, which contains 8.77g of water vapor (absolute humidity) .

We cool the air up to +12.01°C. Air at this temperature, with 8.77 g/kg of water vapor, is saturated, that is, has a relative humidity of 100%. This is the dew point .

We go on cooling, going below the dew point, bringing the air to +11.99°C. The relative humidity remains at 100%, but the absolute humidity has become 8.76 g/kg. We have condensed, transformed from steam to liquid, 0.1 grams of water. We have dehumidified the dry air of 0.1g.

We cool it again, this time going a bit more below the dew point, we bring the kg of air down to +2°C .

The relative humidity does not change, remaining at 100%, but the absolute humidity reaches 4.384g. We had 8.76, and 8.76 to 4.384 = 4.37. We removed from our kg of air other 4,37 g of water vapor, making condense, or making them liquid .

So, to summarize , we started with 1 kg of air at + 20°C with 60%, that is, containing 8.77 g of water vapor and having a dew point of +12.01 and we cooled to to + 2 ° C by removing 4.37 g of water vapor (making it condense). We now 1kg of air at + 2°C saturated (100% RH) containing 4.384 g of water vapor.