Caratterizzazione termo-fluidodinamica ed ottimizzazione delle prestazioni di un prototipo di refrigeratore magnetico a magneti permanenti rotanti operante a temperatura ambiente

The main purpose of the present work was the completion and the thermo-fluid dynamic characterization of a Rotary Permanent Magnet Magnetic Refrigerator operating at room temperature. The experimental device consists of 8 static regenerators packed with gadolinium (Gd) spheres inside a rotating two-pole permanent magnet with a magnetic field of 1.25 T and an air gap of 43 mm. A rotary valve mechanically coupled to the field generator imparts the direction of heat transfer fluid through the regenerators. A parametric study of the temperature span, cooling power and coefficient of performance (COP) was carried out over a range of different hot reservoir temperatures, volumetric flow rates, cycle frequency and cooling powers. The experimental investigation has been identified by 468 tests on 33 measured quantities, obtaining the thermo-fluid dynamic characterization of the complete machine in stationary operation. Finally, with the aim of optimising the performance of the prototype, a new regenerator has been developed. The new design allows reducing the dead volume and improves the fluid distribution around the magnetic refrigerant. [edited by Author]