CH-18-002 -- Analysis of Magnetic Refrigeration Designs with Three Different Magnet Array Geometries

Magnetic refrigeration is one of the promising alternativecooling technologies in terms of its theoretical limits. However,applications of these systems yield much lower coefficient ofperformance (COP) values than the Carnot COP values thatcan be achieved at room temperatures. The main challengesare the limited magnetocaloric effect of the magnetocaloricmaterial and space limitations. To address the magnetic fieldand heat transfer enhancement problems, three different geometries(circular, octagonal, and hexagonal) of Halbach magnetarray and magnetocaloric material assemblies were simulatedwith the aid of theoretical analysis. Magnetic flux intensitieswithin the apertures of each hollow design were obtained usingFinite Element Method Magnetics (FEMM) software (FEMM2013). Resulting entropy and temperature changes and correspondingheat flux boundary conditions around the magnetocaloricmaterial is placed concentrically within the magnetarray were calculated. Findings were implemented intoANSYS (ANSYS 2016) to observe the thermal behavior ofwater, which is selected as the working fluid in this study. Heattransfer rates to the working fluid were compared. Resultsshow that the circular Halbach arrays yield higher heat transferrates, not because of the flow structure, but because ofachievement of an enhanced magnetic field within circulararrays.