rexresearch
Stefan SEELECKE, et al.
Nitinol Refrigerator
http://emediapress.com/2019/04/09/400-600-overunity-cooling-machine/
OverUnity Cooling Machine
The cooling system methodology created by a team led by Professors Stefan Seelecke and Andreas Schütze at Saarland University is technically not new in concept, but it is the best example of taking advantage of an interesting memory metal called Nitinol and it’s known effects of soaking up heat while it gets bent and releasing the heat when it straightens out.
The cooling system is made of a cylindrical chamber with a rotor that has nitinol metal strings running along the length. There is a cam system that flexes the wire as it rotates for 1/2 the revolution. During this 1/2, the wires soak up heat in that compartment, which cools the compartment down. When the wires goes into the other side of the chamber, they are allowed to straighten up and they release a lot of heat, which heats up that compartment.
There is air moving through the devices to move both the hot and cold air. The claims from the university is that it is about twice as efficient as a heat pump. As you know from the examples above that a heat pump could have a COP of 2.0 or 3.0 easily. That means that this new Nitinol cooling device would have a COP of 4.0-6.0 or 400-600% more work done than the motor takes to rotate the cylinder!
https://www.asminternational.org/web/smst/newswire/-/journal_content/56/10180/26145309/
http://www.uni-saarland.de/nc/en/news/article/nr/14195.html
Shape memory Nitinol alloys designed to cool refrigerators
Saarland University, Germany, reports that its engineers are using shape memory alloys to develop a new method of cooling in which heat and cold are transferred by a nickel-titanium alloy...
If a nickel-titanium wire or sheet is deformed or pulled in tension, the crystal lattice structure can change, creating strain within the material. This change in the crystal structure, known as a phase transition, causes the shape memory alloy to become hotter. If the stressed sample is allowed to relax after temperature equalization with the environment, it undergoes substantial cooling to a temperature about 20 Centigrade degrees below ambient temperature. ‘
"The basic idea was to remove heat from a space – like the interior of a refrigerator – by allowing a pre-stressed, super-elastic shape memory material to relax and thus cool significantly. The heat taken up in this process is then released externally to the surroundings. The SMA is then re-stressed in the surroundings, thereby raising its temperature, before the cycle begins again," explains Stefan Seelecke, Professor for Intelligent Material Systems at Saarland University.
In the experimental and modelling studies carried out so far, the researchers at Saarland University and the Center for Mechatronics and Automation Technology (ZeMA) in Saarbrücken have demonstrated that this type of cooling works, and that it can be used in practice. They used a model system to determine how to optimize the efficiency of the cooling process, examining such factors as how strongly the material has to be elongated or bent in order to achieve a certain cooling performance, or whether the process is more effective when carried out slowly or more rapidly. A thermal imaging camera was deployed to analyze precisely how the heating and cooling stages proceed...
DE102016118776 -- ENERGY CONVERTER WITH THERMOELASTIC ASSEMBLY AND HEATING/COOLING SYSTEM
The invention relates to a thermoelastic energy converter (1), in particular a thermoelastic heating / cooling device, for use in an energy converter system, comprising: - a thermoelastic arrangement with at least one thermoelastic element (2) of a thermoelastic material; - Two holding elements (3, 4), between which the at least one thermoelastic element (2) is arranged in the longitudinal direction; - A fastening element (6) for holding one end of the at least one thermoelastic element (2); - A guide means (7) which is coupled to the fastening element (6) of the at least one thermoelastic element (2) to a synchronous rotation of the holding elements (3, 4) relative to the guide means (7) a change in length of the at least one thermoelastic To cause elements (2) in the longitudinal direction, so that a cyclic elastic deformation and relaxation of the at least one thermoelastic element (2) is achieved.
WO2017194591 // DE102016108627 -- BISTABLE ACTUATOR DEVICE HAVING A SHAPE MEMORY ELEMENT
The invention relates to an actuator device (1) for providing at least two actuator positions, comprising an elastic bending element (2), which at at least one fastening point (31, 32, 34) is held such that by exerting a switching torque at the fastening point (31, 32, 34), an elastic deformation of the bending element (2) leads to a change from a first actuator position into a second actuator position, and comprising at least one actuator element (41, 42) having a shape memory wire, wherein by heating, the shape memory wire generates a tractive force, and is thus coupled to a section of the bending element (2) at the fastening point (31, 32, 34), such that the tractive force causes the switching moment to be brought about at the fastening point (31, 32, 34) in order to move the bending element (2) from the first actuator position into the second actuator position.