Evaporative cooling is a system in which latent heat of evaporation is used to carry heat away from an object to cool it. The latent heat contains a considerable amount of energy, and carries away more heat than if the same temperature liquid was simply removed physically. Latent heat describes the amount of energy in the form of heat that is required for a material to undergo a change of phase (also known as change of state). Two latent heats are typically described. ... Water vapor condensing over a cup of hot tea Evaporation is one of the two forms of vaporization. ...

The simplest example would be sweat, which the body secretes in order to cool itself. The amount of heat transfer depends on the evaporation rate, which in turn depends on the humidity of the air and its temperature, which is why you sweat more on hot, humid days. Humidity is the concentration of water vapor in the air. ...

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 based on 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 (Prestone) instead. The Germans instead used clever streamlining and positioning of traditional radiators. Even its most ardent supporters, Heinkel's Günter brothers, eventually gave up on it in 1940. Ethylene glycol (monoethylene glycol (MEG), IUPAC name: ethane-1,2-diol) is an alcohol with two -OH groups (a diol), a chemical compound widely used as an automotive antifreeze. ... Heinkel Flugzeugwerke was a German aircraft manufacturing company founded by and named after Ernst Heinkel. ... Siegfried and Walter Günter were twin brothers and aircraft designers. ...

Evaporative cooling is a very common form of industrial and residential cooling since it is relatively cheap and requires less energy than many other forms of cooling. However evaporative cooling requires an abundant water source as an evapourate, and is only efficient when the relative humidity is low, restricting its effective use to dry climates. In the US these units are colloquially referred to as swamp coolers. Swamp coolers (also called evaporative coolers or Air coolers) are air conditioners used to cool buildings in dry climates. ...

Evaporative cooling is commonly used in cryogenic applications. The vapor above a reservoir of cryogenic liquid is pumped away, and the liquid continuously evaporates as long as the liquid's vapor pressure is significant. Evaporative cooling of ordinary helium forms a 1-K pot, which can cool to at least 1.2 K. Evaporative cooling of helium-3 can provide temperatures below 300 mK. Each of these techniques can be used to make cryocoolers, or as components of lower-temperature cryostats such as dilution refrigerators. As the temperature decreases, the vapor pressure of the liquid also falls, and cooling becomes less effective. This sets a lower limit to the temperature attainable with a given liquid. Cryogenics is a branch of physics (or engineering) that studies the production of very low temperatures (below −150°C, −238°F or 123K) and the behavior of materials at those temperatures. ... Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... A 1-K pot (i. ... Helium-3 is a non-radioactive and light isotope of helium. ... Cryocoolers are refrigerators used to reach cryogenic temperatures. ... Cryocoolers are refrigerators used to reach cryogenic temperatures. ... A dilution refrigerator is a cryogenic device first proposed by Heinz London. ...

This process has recently been observed to operate on a planetary scale on Pluto and acts as an Anti-Greenhouse Effect. Adjective Plutonian Atmospheric characteristics Atmospheric pressure 0. ... The Anti-Greenhouse Effect describes the cooling effect an atmosphere has on the ambient temperature of the planet. ...

External links

• Evaporative cooling simulation
• Evaporative Cooling Vests and more