Convegni ATI - Accesso riservato soci CTI

Autore: C. Aprea, A. Maiorino, A. Rowe, A. Tura

Collana: CA - 62 - Fisciano 2007

Note:
Magnetic refrigeration is an emerging technology based on the magnetocaloric effect in solid-state refrigerant.
This technology offers a smaller ambient global impact than the refrigeration obtained by means of the classical vapour compression machine operating with fluids such as HFCs.
The Active Magnetic Regenerative Refrigeration (AMRR) is currently the most studied ant tested magnetic cycle. It combines the regenerative properties of a high specific heat solid porous matrix with the ability of performing thermo-magnetic cycles thanks to the magnetocaloric property of the refrigerant; while a fluid pulsing through the regenerator works as a heat transfer medium. An active magnetic regenerator can provide larger temperature spans compensating for the local small temperature variation of the refrigerant.
While conceptually simple, many technical challenges have confined this technology to laboratory apparatuses. In particular the need of intense magnetic field, magnet cost and size compared to the effective available refrigerant volume, the small, strongly non-linear temperature–dependant magnetocaloric effect (MCE), and the pressure drop across the AMR have limited the efficiency and the performance of these systems.
In order to produce magnetic cycles it is necessary to apply a relative motion between the magnets and the regenerators. Most designs have used a rotating or a reciprocating approach. Rotary systems seem to be the promising solution for commercial applications because they can operate at yigher frequencies, thus outputting higher cooling power. AMR rotation allows for small mass movement; however the challenge of dynamic sealing needs to be faced. If instead magnets are rotated, sealing is simplified, but it is necessary to deal with a larger moving mass.