Evaporative Cooling History

Evaporative Cooling History

Civilizations throughout the ages have found ingenious ways to combat the heat in their region. An earlier form of air cooling, the windcatcher (Bâd gir), was invented in Persia (Iran) thousands of years ago in the form of wind shafts on the roof, which caught the wind and passed it through water and blew the cooled air into the building.[1] Nowadays Iranians have changed the windcatcher into an evaporative cooler (Coolere Âbi) and use it widely. There are 9,000,000 evaporative coolers in central Iran, and in just the first two months of year 1385 in the (Persian/Iranian calender) (April–May 2006) 130,000 evaporative coolers were sold in Iran.
Evaporative cooling was in vogue for aircraft designs for some time in the late 1930s. In this case the system was used in order to reduce, or eliminate completely, the radiator which would otherwise create considerable drag. In these systems the water in the engine was kept under pressure with pumps, allowing it to heat to temperatures above 100 Celsius, as the actual boiling point is a function of the pressure. The super-heated water was then sprayed though a nozzle into an open tube, where it rapidly boiled and released its heat. The tubes could be placed under the skin of the aircraft, resulting in a zero-drag cooling system.
However these systems also had serious disadvantages. Since the amount of tubing needed to cool the water was large, the cooling system covered a significant portion of the plane even though it was hidden. This led to all sorts of added complexity and the systems were always terribly unreliable. In addition this large size meant it was very easy for it to be hit by enemy fire, and practically impossible to armor. British and US attempts to use the system turned to ethylene glycol instead. The Germans instead used streamlining and positioning of traditional radiators. Even its most ardent supporters, Heinkel’s Günter brothers, eventually gave up on it in 1940.
Evaporative cooling was used in some automobiles, often as aftermarket accessories, until modern vapor-compression air-conditioning became widely available.

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