The fundamental principle of the Magneto-Caloric Effect (MCE) was discovered by E. Warburg (1881) and further on studied by Debye (1926) and Giauque (1927). The first magnetic cooling system for a very low temperature (0.25 K) was built in 1933, leading to a Nobel Prize in physics in 1949.
Emil Gabriel Warburg
The magnetocaloric effect (MCE) results in a few Kelvin reversible temperature change within a magnetocaloric material when a magnetic field is applied. The material reaches the initial temperature once the magnetic field is removed.
The magnetocaloric effect:
Permanent magnet materials will be employed as field source within the ICE project. This is usually done for systems requiring a high cooling power. In the end of the 20th century an important progress has been done in NdFeB-based permanent magnets.
The whole system has to be designed properly in order to achieve a maximal magnetic induction in the maximum volume of active MCE materials and to permit the alternate and repetitive variation of the magnetic field. With this technology, thermal COPs between 2 and 22 can be achieved, thus higher than in conventional vapour-compression chillers.
The heat transfer is also a key issue in such machines. The fluid flows back and forth between the thermal sources, passing through the magneto-caloric element:
The machine designed for the ICE project uses an AMR (active magnetic regenerator) which is a regenerator made of magnetocaloric material exposed to a periodic intermittent magnetic field. A temperature gradient is created along the regenerator, as shown in the next IR picture of the ICE project magnetocaloric heat pump prototype.