How beaming heat into space could form the air conditioning systems of the future
In space, nobody can hear you switch your air conditioning system on. Thanks to a recent test at Stanford University, outer space could be the source of our future HVAC system. Using radiative cooling, heat is beamed from the Earth’s surface into outer space. Zhen Chen and his colleagues at the university lowered the temperature by means of a thermal emitter.
A thermal emitter gives out more heat than it takes in. Through high performance cooling measures, it is coupled with an object in outer space. Then it is decoupled from the ambient environment. What makes it possible is the earth’s atmosphere itself. The Earth’s atmosphere allows the thermal radiation of wavelengths measuring 8 to 13 micrometres.
Previous experiments have only seen a temperature reduction of 20 degrees Celsius. Stanford University’s study has recorded more significant drops in temperatures. From a starting temperature of 42.2 degrees Celsius, it dipped to 40 degrees Celsius within half an hour. Over a 24 hour period, temperatures were on average 37 degrees Celsius below the air temperature. Its biggest temperature drop was achieved when exposed to the sun’s heat.
In New Scientist magazine, Jeremy Munday, from University of Maryland in College Park said: “They’re getting significantly below water-freezing temperature during daylight by improving their set-up.” He attributed their success to the use of vacuum chambers and sun shades.
For their findings they used zinc selenide, though cheaper materials like silicon or aluminium can be used.
ST Maintenance Solutions, 14 December 2016.
* With apologies to Jim Henson.