Dew point

The dew point temperature is the temperature where the water content in the air condenses into water. This means that the water content in the air changes states from gas to liquid.

The dew point temperature is the temperature where the water content in the air condenses into water. This means that the water content in the air changes states from gas to liquid.

The dew point is related to the relative humidity. When the relative humidity increases, the difference between the dew point temperature and the air temperature decreases. When the relative humidity is 100%, the air temperature and dew point temperature are the same.

The dew point temperature is used for example during dimensioning of cooling and ventilation systems to avoid build up of water and ice on the cooling surface. If the air is cooled on a cooling surface, then the cooling surface temperature must be higher than the dew point temperature to avoid condensate from forming.

The accompanying h, x diagram is for humid air at 1013 mbar. The absolute water content in humid air (x), relative humidity (%), temperature (ºC), and enthalpy (h) can be read in the diagram.





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