Doesn’t it sound like magic that a device that sits under the blazing sun outdoors and gets cooled down by itself by almost 13 degrees Celsius or more without consuming any electric power? Well, it is not some magic but a device designed by MIT researchers.
The device works by the principles of a process called radiative cooling, doesn’t have any moving parts. It prevents itself from getting heated up by blocking the incoming sunlight and simultaneously emits infrared light – which is mainly heat that is passed into space or the sky, and eventually, the device gets cooled significantly.
The key to this function is simple and inexpensive insulation called aerogel which is made up of polyethylene foam. This material is exceptionally lightweight and has almost the same feel as a marshmallow. It reflects the sunlight after blocking them, and thus they don’t get to penetrate it. But it works otherwise in the reverse time which means it acts as a transparent material for the heat-carrying infrared rays and they are allowed to pass towards the outward direction.
Arny Leroy, an MIT graduate and Evelyn Wang, head of the department as well as a professor of mechanical engineering along with seven other students at the MIT and the Pontifical Catholic University situated at Chile, described the new system in a paper and published it on a journal called Science Advances on the 30th Oct’19.
Leroy says that this kind of system will be helpful to store the vegetables and fruits fresh for a long time in places where refrigeration is still not available.
Most of the hot objects use the process of radiative cooling to get cooled down. They emit the infrared radiation which is set off directly into space from the purpose, as the air acts transparently to the infrared light.
The insulation is solved by developing a different type of aerogel. Aerogels are generally very lightweight material that consists of primary air that provides thermal insulation. But the team made aerogel from polyethylene which is used in making polythene bags. It resulted in a squishy, soft and white material that turned out to be so lightweight that even the most massive volume feels like 1/50 of water.
The blockage of about 90% of the incoming sunlight is the success key of the system which protects the below surface from getting heated. While passing emitted heat outwards, it allows about 80% it. Below the insulator, a plate, called the emitter made up of ceramic and metal is cooled down dramatically. The plate then cools the container that is connected to its body as well as the liquids that pass through the coil connected to it.
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