Black technology: no need for refrigerant, the efficiency is three times that of air conditioning! ! !
The device is based on the special properties of certain shape memory metal alloys and will return to its original shape after deformation. In some cases - especially nickel-titanium, also known as nickel-titanium alloy - these metals absorb a large amount of heat when bent and then release heat when they are allowed to return to their normal shape. The difference between the load line and the release line can be as high as 20 ° C (36 ° F).
The cooling device is therefore very simple in concept. It uses a rotating cylinder that covers the nitinol wire harness. As these lines pass through one side, they draw heat from the air and store it. Then as they rotate past the other side, they are allowed to bounce back into shape, "dumping" the heat on the second side. Air is blown through the chamber on each side to provide a heated air and another cooling air. The research team at the University of Saar has been experimenting with this device to determine the wire load, the speed of rotation, and the optimal convergence of how many wires should be bundled to create the maximum possible thermal difference between the two sides at a given energy input.
The results seem very exciting. The team at the University of Saarland stated that “the heating or cooling power of the system is thirty times higher than the mechanical power required to load and unload the alloy wire harness,” depending on the type of alloy used. They say that this makes their new system twice the price of a conventional heat pump and three times that of a conventional refrigerator.
“Our new technology is also environmentally friendly and does not pose a hazard to the climate because the heat transfer mechanism does not use liquid or steam,” said Professor Stefan Seelecke, president of the University's Smart Metal Systems. “Therefore, the air in the air conditioning system can be cooled directly without the need for an intermediate heat exchanger, and we don’t have to use leak-free high pressure piping.”
The idea of air cooling or heating only by bending and bending small pieces of metal sounds strange. How about metal fatigue? How long will these alloy wires last in these variable temperature environments before becoming brittle and fractured?
In fact, this is an area where Nitinol is very different from other metals. Nitinol is most commonly used in medical devices, especially implantable devices such as stents, where the superior flexibility allows the stent to flex, squeeze, stretch and twist as the body moves.
Therefore, Verdict Medical Devices summarizes the fatigue properties of Nitinol: “It is by far the most resistant metal known in high-amplitude strain-controlled fatigue environments. Multiple applications... just because it is very Nickel-titanium alloy is used for fatigue resistance."
The above described cooling device appears to be in line with the description of high amplitude, strain control applications. But, of course, it is up to the researcher or the future business team to prove how long your Nitinol reverse cycle "air conditioning" can last.