A team of German researchers has taken the veils off of a prototype that features a unique heating/cooling system based on nitinol. The contraption stresses and unloads nickel-titanium ‘muscle wires’ for the sake of creating heated and cooled air. The system works at twice the efficiency of a heat pump or thrice the efficiency of an air conditioner. More importantly, the system doesn’t require any refrigerant gases thus being more environmentally friendly.
The contraption makes use of a bizarre property of particular shape-memory metal alloys that are capable of restoring to their original shape after being deformed. For some alloys, especially nickel-titanium, more commonly known as nitinol, they are able to absorb tremendous amounts of heat while getting bent out of shape. They release this energy when they spring back into their original shape. The difference between the deformed and released wire can be as much as twenty Celsius degrees.
The cooling contraption, therefore, is quite simple. It employs the use of a rotating cylinder that has been covered using nitinol wire bundles. These wires are loaded up as they pass through one side; sucking heat out of the air and absorbing them. Then they are allowed to revert back as they rotate past the other side thus releasing the heat on the other side. Air is blown via chambers on each side enabling one feed of heated air and another feed of cooled down air.
The team from Saarland University has been carrying out experiments with this amazing device for coming up with optimal values for tasks such as the rotational speed, convergence of wire loading, and number of wires that are to be in a bundle for being able to harness the maximum possible differential of heat between the two sides from any given energy input.
The results are quite promising. Professor Stefan Seelecke, the university’s Chairman of Intelligent Metal Systems, said, ‘Our new technology is also environmentally friendly and does not harm the climate, as the heat transfer mechanism does not use liquids or vapors. So the air in an 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.’
If this pans out; we are looking at a heating/cooling technique that is super-efficient as opposed to current methods of heating and cooling and the removal of refrigerant gases!