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NEWSCIENCENEWSCIENCENEWSCIENCE September, but only half that much in designs employed an electric fan for greater "Apparatus for the purification of non- 1931. The maximum yield was 5.5 lb/day. —_ airflow. At 90°F and 80% relative humidi- _ potable water comprising, in combination, Chaptal found that the condensing sur- ty (RH), the air well yields about 60 lb an installation for heating a circulating face must be rough, and the surface tension water daily. At 20% RH, the yield is only mass of air, said installation comprising at sufficiently low that the condensed water about 3 lb/day. The yield is even lower at least one tubular element through which can drip. The incoming air must be moist lower temperatures. said air circulates and at least one trough- and damp. The low interior temperature is It is difficult to calculate the amount of _ like mirror of parabolic section having the established by re-radiation at night and by water that can be collected. The yield focal axis thereof horizontally disposed, the lower temperature of the soil. Air flow depends on the amount of air and its rela- with said tubular element disposed along was controlled by plugging or opening the tive and specific humidity, and the soil _ said focal axis of said mirror, said mirror vent holes as necessary. temperature, thermal conductivity and _ with its associated tubular element being Chaptal drew his inspiration from a sur- moisture. Acoustic resonance within the mounted in the plane of symmetry of said prisingly successful experiment by pipes might enhance condensation. The mirror, and also being mounted to rotate Friedrick Ziebold, who constructed an _ more recent invention of acoustic refrigera- about a vertical axi: 9.10 atmospheric condenser atop a hill at _ tion could be used to advantage, as well as Coanda also received USP #2,761,292 Feodosia (Theodosia), Crimea, modelled — the Hilsch-Ranque vortex tube. for his "Device for Obtaining Drinkable after the ancient air wells discovered there The water collected by the Courneya air Water". He offered the following in 1900. Ziebold's condenser was a pile of _ well is relatively pure, equivalent to single- explanation: sea pebbles (10-40 cm diam.), 20 metres in distilled water. Analysis of water collected "It is known that the air contains water, diameter and 1.15 metres high. The con- _ by an air well near a busy street found no and according to my invention the energy struction yielded up to 360 litres/day until — sulphur or lead (measured in ppm). for precipitating this water can be taken from the air itself in motion. It is known that for a given tempera- ture a given volume of air may not contain more than a certain quan- tity of water vapour. When it con- tains this quantity it is said to have reached its saturation point. Moreover, this point varies with the temperature, and the cooler the air, the less water vapour it may contain for a given volume. "Consequently, when a relative- 1915, when it began to leak due to a crack in the wall. ¢ Calice Courneya patented an air well in 1982 (USP #4,351,651): "A heat exchanger at or near sub- surface temperature...is in air com- munication with the atmosphere for allowing atmospheric moisture— laden air to enter, pass through, cool, arrive at its dew point, allow the moisture to precipitate out, and allow the air to pass outward to the atmosphere again. Suitable appara- ly warm volume of moist air is tus may be provided to restrict air cooled to a sufficiently low tem- low and allow sufficient residence _ Friedrick Ziebold's Atmospheric Condenser, Feodosia, Crimea, 1912 perature, it yields the water it con- time of the air in the heat exchang- (Photo: International Organization For Dew Utilization) tained in excess over the quantity er to allow sufficient precipitation. ermitted by the saturation point at the Furthermore, filtration may be provided on «In the 1950s, the French inventor Henri temperature to which it has been cooled. the air input, and a means for creating a Coanda designed an elegant method to "In a continuous process of producing [negative] movement pressure, in the pre- produce pure water from saline. He _ fresh water, it is necessary to absorb the ferred form of a turbine, may be provided designed an enormous silo with reflective heat derived from the warm moist air at a on the output... walls, which was mounted several inches speed corresponding to the rate of "The air well is buried about 9 feet deep. _ over a tidal pool. The silo was angled so as __ cooling..." The entrance pipe is 3-inch diameter PVC to catch and multiply the sunlight, thus Coanda recommended that the condenser pipe (10 feet long), terminating just near superheating the air in the chimney. The e buried so that the earth could absorb the the ground... This is an advantage because rising hot air drew in cold air from the bot- _ heat: the greatest humidity in the atmosphere is tom, and became super-saturated with "For example, one cubic metre of air near the surface.""* moisture by the time it reached the top. from a wind whose temperature is about In a preferred embodiment, the intake is Fans then pulled the air through acon- 40°C can contain up to about 50 grams of provided with a cyclone separator to pre- denser, from which pure water flowed. water vapour; if the wind is forced to enter cipitate dust before the air enters the pipe. The residual brine is of great value to the a certain space by passing along...a In addition, a flow restrictor device can be chemical industry and in the construction _ radiator in which a fluid circulates at the installed before the exit port. of solar ponds. The French government temperature existing 7 or 8 metres below Air flows through the pipes at 2,000 forced Coanda to cease operations because _ the ground level, that is, of about 11°C, this cubic feet per hour at 45°F with a5 mph his device threatened their monopoly on _ wind will immediately precipitate on the wind. This translates to about 48,000 _ salt production. radiator walls the portion of the water feet*/day (over 3,000 lb of air daily). Coanda described his "Apparatus for content which is in excess of that permitted Courneya's first air-well used a turbine Purification of Undrinkable Water" as fol- by its saturation point at the cooler fan to pull air through the pipes. Later lows in the abstract of his USP #2,803,591: temperature, that is, about 40 grams per designs employed an electric fan for greater airflow. At 90°F and 80% relative humidi- ty (RH), the air well yields about 60 Ib water daily. At 20% RH, the yield is only about 3 Ib/day. The yield is even lower at lower temperatures. It is difficult to calculate the amount of water that can be collected. The yield depends on the amount of air and its rela- tive and specific humidity, and the soil temperature, thermal conductivity and moisture. Acoustic resonance within the pipes might enhance condensation. The more recent invention of acoustic refrigera- tion could be used to advantage, as well as the Hilsch—Ranque vortex tube. The water collected by the Courneya air well is relatively pure, equivalent to single- distilled water. Analysis of water collected by an air well near a busy street found no sulphur or lead (measured in ppm). Friedrick Ziebold's Atmospheric Condenser, Feodosia, Crimea, 1912 (Photo: International Organization For Dew Utilization) In the 1950s, the French inventor Henri Coanda designed an elegant method to produce pure water from saline. He designed an enormous silo with reflective walls, which was mounted several inches over a tidal pool. The silo was angled so as to catch and multiply the sunlight, thus superheating the air in the chimney. The rising hot air drew in cold air from the bot- tom, and became super-saturated with moisture by the time it reached the top. Fans then pulled the air through a con- denser, from which pure water flowed. The residual brine is of great value to the chemical industry and in the construction of solar ponds. The French government forced Coanda to cease operations because his device threatened their monopoly on salt production. Coanda described his "Apparatus for Purification of Undrinkable Water" as fol- lows in the abstract of his USP #2,803,591: NEXUS 45 DECEMBER 2002 — JANUARY 2003 www.nexusmagazine.com