Dew point
Saturated air at 25C, with water vapour content of 0.020 16 kg/kg, can be represented as a point on a graph of relative humidity temperature (Fig. 20.1). Air, which is 50% saturated at this temperature will contain 0.010 08 kg/kg and will appear on this chart point B. this 50% saturation mixture is cooled slowly, by changing the state will be along the lines BC, with constant humidity, but also the decrease of temperature. It gets to a point C on the saturation line, where maximum moisture it can hold 0.010 08 kg/kg (approximately 14.2C). It cannot be cooled below this temperature and until now the share of water vapor, so moisture will condense in the form of dew. Point C for original mix at B is called the dew point.
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