Air fountain
Different types of systems are referred to as air wells in which air either flows through underground cavities or the ground or in which moisture is extracted from the ambient air through condensation .
Air well as geothermal heat exchanger
In most air to geothermal heat exchangers , the air is routed through pipes . In the special case of an air well , the air instead flows either directly through permeable soil, through gravel packs or through other types of underground cavities.
A radon exposure of transported air by direct contact with soil or rock radon loaded with gravel bed should be avoided for health reasons. Contact with the ground can be avoided by installing a film between the gravel and the ground.
Air well for removing pollutants
For the removal of contaminated sites and the decontamination of soil that is polluted with volatile solvents, air wells are created from which the soil air can be extracted, for example with side channel compressors or rotary vane compressors . For this purpose, holes with a diameter of 300 mm are typically made and filled with a filter slot tube and filter gravel. The seal against the ambient air is made by swelling clay or concrete .
Air wells for the extraction of condensation water
Air wells (French “Puits aerien”, English “Air well” (condenser)) were already known in ancient times. They were used for room cooling and water extraction from the air. The oldest known system of this type is the air well, originally a Greek colony of Teodosia in the Crimea from the 4th century BC , which was destroyed by the Huns . Chr.
The principle is based on the high temperature difference between outside and inside or between day and night temperature, which allows the humidity to condense.
Archaeologists and engineers are currently researching whether there are older wells that correspond to the construction principle of the underground air well described in the Economic Encyclopedia by Johann Georg Krünitz , using the well in Santa Cristina near Paulilatino in Sardinia. It is still unclear whether the amount of water produced was sufficient to accept water production as the reason for the building.
Knapens air well
The Belgian engineer Achille Knapen looked at the possibilities of dehumidifying buildings. Inspired by the work of the Frenchman Leon Chaptal, he built an air fountain on a 180 meter high hill above Trans-en-Provence within 18 months in 1931 . The now somewhat dilapidated tower in Trans-en-Provence is 14 meters high, has wall thicknesses of up to 3 meters and aroused public interest when it was built.
The warm and humid outside air can flow into the interior through a number of openings, cools down on a solid concrete column, sinks down and exits the building again below. When it cools down, the moisture in the air condenses on the column and is collected. According to Chaptal's findings, the condensation surface should be rough and have a low surface tension . The central concrete column was therefore equipped with protruding slates that were almost vertically aligned to facilitate the drainage. However, the water yield was disappointing and was only a few liters per day.
Similar heat exchangers
Air siphon
A simple variant of air preheating is achieved by a so-called "air siphon" which ends at the bottom of a shaft or an unused house well. An air siphon without air preheating consists, for example, of an air duct that leads from a cellar window, an air shaft or a ventilation opening to the cellar floor and enables the entry of fresh air, which is required by a room air-dependent heating system, while at the same time preventing warm, rising room air from escaping to the outside . Cold outside air, which initially sinks to the bottom of a shaft, heats up as it rises up the walls of the shaft. It should be noted that the water pipes in the shaft can freeze in winter.
Hypo exchanger in the winter garden
In winter gardens , a so-called "hypo exchanger" system is sometimes used, with which overheating and drafts can be avoided. In the warm air in the winter garden, water (irrigation water or fountain water) evaporates and thus extracts heat from the air; The moist air that has risen is extracted mechanically at the highest point in the winter garden and passed through hypocaust pipes that are laid in the floor or the walls of the building. The water vapor condenses in the hypocaust and the released heat of condensation is transferred to the structure. The dehumidified air is then fed back into the winter garden and enables further cooling through evaporation.
Individual evidence
- ^ Luftbrunnen , GUT Society for Environmental Technology mbH, Friedberg-Ockstadt; accessed in September 2019
- ^ British Knapen - The Early Years . ProTen Services. Archived from the original on May 9, 2009. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved September 10, 2010.
- ^ Prevention Of Damp in Buildings. The Manchester Guardian , February 27, 1930 p. 6 column F.
- ↑ Proten Services Celebrates 80 Years of Service . ProTen Services. Archived from the original on May 24, 2010. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved September 10, 2010.
- ^ Well Like Gigantic Ant Hill Gathers Water from Air . In: Popular Mechanics . 58, No. 6, December 1932, p. 868. Retrieved September 10, 2010.
- ↑ "Air Well Waters Parched Farms" Popular Science , March 1933
- ↑ Achile Knappen: Improved means for collecting moisture from the atmosphere . European Patent Office. Retrieved September 10, 2010.
