An essential tool for air dehumidification
The diagram of humid air, also known as the psychrometric diagram, is an essential tool in heating and ventilation engineering as well as thermodynamics. It represents the thermodynamic properties of air, such as temperature, humidity, enthalpy and density. This diagram makes it easy to visualise and calculate air transformations, such as cooling, heating, humidification or dehumidification. By using the diagram of humid air, engineers and technicians can optimise air conditioning systems and ensure a comfortable and healthy indoor environment.
The structure of the diagram of humid air
The psychrometry diagram is the best way of representing changes in the state of the air and water vapour. In the diagram, the horizontal data on the abscissa is the ordinary temperature or dry temperature. The vertical data on the ordinate corresponds to the quantity of water vapour expressed in grams contained in each kilogramme of dry air, at normal atmospheric pressure.
At dew point, the water vapour contained in the air is saturated. It is said that the humidity level of the air is 100%.
The hygrometric degree curve
The curve (red) that passes through all the points where the water vapour is saturated is called the “saturation curve”; it is also when the hygrometric degree is at 100% and the curve shows the location of the dew points.
The curves of constant hygrometric degree for unsaturated air have the same shape as the saturation curve. The hygrometric degree, or relative humidity, represents the actual amount of water contained in the air, compared to the maximum amount it can absorb at the given temperature.
Humidity levels
Three unit values of humidity:
Dew point temperature (°C): this is the temperature to which the air must be cooled for the water it contains to begin condensing into dew droplets. It indicates the point of saturation of the air at a given humidity.
Relative humidity (%RH): this is the percentage of the amount of moisture in the air relative to the maximum amount the air can hold at a given temperature. It indicates how close the air is to saturation.
Absolute humidity (gwater/kgdryair): this is the mass of water contained in one kilogramme of dry air. It measures the actual amount of water vapour in the air, regardless of the temperature.
Discover the map of humidity and climates in France: a reference tool for air dehumidification.
About us
Since 1999, DESSiCA has specialised in the design and manufacture of air dryers, air dehumidifiers, and air dehydration systems for professionals and industries. Based in the Auvergne-Rhône-Alpes region, the company showcases French expertise by producing high-quality equipment. The DESSiCA team, made up of engineers, technicians, and project managers, relies on its strong internal skills to meet the specific needs of its clients.
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