Un système avancé de froid magnétocalorique (en anglais)
Des chercheurs ont conçu un système qui utilise avec succès de très petites quantités de matériaux magnétocaloriques pour produire une puissance frigorifique d'environ 10 watts, avec un gradient de température de 15 °C.
A team of US researchers at Ames laboratory has designed and built a system which uses very small quantities of magnetocaloric materials such as gadolinium. Called CaloriSMART (SMART standing for Small Modular Advances Research-scale Test-station), the system was designed for the rapid evaluation of materials in regenerators without a large investment in manufacturing time.
According to the press release of Ames Laboratory, "the initial test subjected a sample of gadolinium to sequential magnetic fields, causing the sample to alternate between heating up and cooling down. Using precisely timed pumps to circulate water during those heating and cooling cycles, the system demonstrated sustained cooling power of about 10 watts, with a 15 °C gradient between the hot and cold ends using only about three cubic centimetres of gadolinium."
The system was built in about 5 months and "3D printing capabilities were used to custom-build the manifold that holds the sample and circulates the fluid that actually harnesses the system’s cooling power. The system also features customized neodymium-iron-boron magnets that deliver a concentrated 1.4 Tesla magnetic field to the sample, and the precision in-line pumping system that circulates the fluid."
For now, the system is still in the research & development stage, but the objective is to develop caloric materials so they can be moved into the manufacturing space at least two or three times faster compared to the 20 or so years it typically takes today, according to the project director Vitalij Pcharsky.
The magnetocaloric testing is just the beginning. The plan is to upgrade the system to work with elastocaloric materials – which reversibly heat up and cool down when subjected to cyclic tension or compression – and electrocaloric materials, which do the same when subjected to changing electric fields. The system will even operate in a combined-field mode that allows a combination of techniques to be used simultaneously.