Air conditioning units consume energy, and cooling accounts for about one-fifth of total electricity use in buildings.
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Cooling systems with no moving parts or environmentally harmful refrigerant liquids or gases can operate nearly twice as efficiently as a standard air conditioning system, which can reduce electricity use.
Most air conditioners and refrigerators rely on compressing and expanding fluids to absorb or release large amounts of heat. Although these systems are relatively inexpensive and simple to produce, they are not very efficient and therefore require a lot of energy – about one fifth of the electricity used in buildings globally – and many of the refrigerants used are environmental. Are harmful from the point of view.
Now, Emmanuel Defay and his colleagues at the Luxembourg Institute of Science and Technology have developed a coolant-free refrigeration device made of lead, scandium and tantalum metals. It can reach a maximum efficiency of more than 60 percent, which is almost twice that of typical single-room air conditioning units.
The technology relies on a principle called electrocaloric cooling, which occurs when an electric field applied to a material changes the direction of electrical charges, causing a temporary increase in temperature and a subsequent decrease when the electric field is removed.
To create their cooling system, Defoe and his colleagues stacked eight strips of a material called lead scandium tantalate, which is electrocaloric, on top of each other and immersed them in a heat-carrying fluid, silicone oil. When an electric field is applied and the strips are heated, the fluid moves to the right, and as it cools, it moves to the left, creating hot and cold zones with a difference of about 20°C. Become permanent areas.
These areas can be used as hot and cold reservoirs, from which oil can be circulated through pipes to cool or heat rooms or objects as desired.
Although the efficiency of the device is theoretically 67 percent, the current design is about 12 percent efficient. Defoe says that it can be improved if a better thermal conductor than lead scandium tantalate is found.
Subject:
- Energy and Fuel/
- materials Science
Source: www.newscientist.com
