Calculation of the Optimal Magnetic Duty Cycle for a Graded Coaxial Magnet of a Rotary Type Magnetic Refrigerator
In the design of a rotary-type magnetic refrigerator, a high field of a coaxial magnet is desired. Typically, a high-field design can be achieved with a small duty cycle, which might not be optimized from the viewpoint of the thermal hydraulics of a magnetic refrigerator. In this work, a numerical s...
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| author | Chih-Hao Lee Pai-Hsiang Cheng Keh-Chyang Leou Chih-Ming Hsieh Yu-Chuan Su |
| author_facet | Chih-Hao Lee Pai-Hsiang Cheng Keh-Chyang Leou Chih-Ming Hsieh Yu-Chuan Su |
| author_sort | Chih-Hao Lee |
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| description | In the design of a rotary-type magnetic refrigerator, a high field of a coaxial magnet is desired. Typically, a high-field design can be achieved with a small duty cycle, which might not be optimized from the viewpoint of the thermal hydraulics of a magnetic refrigerator. In this work, a numerical simulation analysis of a graded coaxial magnet designed using a COMSOL program for a rotary-type active magnetic refrigeration (AMR) system was performed. The magnet structures are based on neodymium–iron–boron permanent magnets with thin gadolinium (Gd) and gadolinium-terbium alloy (Gd-Tb) plates as AMR materials. For a rotary-type magnetic cooling system, from the thermal–hydraulic point of view, the best duty cycle of a coaxial magnet should be 50% if the magnetic field can be kept constant during the period of duty cycles. However, the simulation calculation shows a serious reduction in the magnetic field strength at higher duty cycles, resulting in lower magnetic cooling efficiency. After considering the thermos-hydraulic part, the optimized duty cycle is around 30% in the case of a temperature span of 8 K between the hot and cold ends on a rotary-type magnetic cooling system. By applying graded Gd-Tb alloy along the flow direction, the performance of magnetic refrigeration improves significantly. Compared to a pure Gd AMR system, it is demonstrated that more than three times the increase in the cooling capacity can be achieved. |
| format | Article |
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| institution | Kabale University |
| issn | 1996-1073 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
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| series | Energies |
| spelling | doaj-art-db1ecf2cbd1f4ab9b6239d5bb0229afa2025-01-24T13:30:54ZengMDPI AGEnergies1996-10732025-01-0118228910.3390/en18020289Calculation of the Optimal Magnetic Duty Cycle for a Graded Coaxial Magnet of a Rotary Type Magnetic RefrigeratorChih-Hao Lee0Pai-Hsiang Cheng1Keh-Chyang Leou2Chih-Ming Hsieh3Yu-Chuan Su4Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, TaiwanDepartment of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, TaiwanDepartment of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, TaiwanDepartment of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, TaiwanDepartment of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, TaiwanIn the design of a rotary-type magnetic refrigerator, a high field of a coaxial magnet is desired. Typically, a high-field design can be achieved with a small duty cycle, which might not be optimized from the viewpoint of the thermal hydraulics of a magnetic refrigerator. In this work, a numerical simulation analysis of a graded coaxial magnet designed using a COMSOL program for a rotary-type active magnetic refrigeration (AMR) system was performed. The magnet structures are based on neodymium–iron–boron permanent magnets with thin gadolinium (Gd) and gadolinium-terbium alloy (Gd-Tb) plates as AMR materials. For a rotary-type magnetic cooling system, from the thermal–hydraulic point of view, the best duty cycle of a coaxial magnet should be 50% if the magnetic field can be kept constant during the period of duty cycles. However, the simulation calculation shows a serious reduction in the magnetic field strength at higher duty cycles, resulting in lower magnetic cooling efficiency. After considering the thermos-hydraulic part, the optimized duty cycle is around 30% in the case of a temperature span of 8 K between the hot and cold ends on a rotary-type magnetic cooling system. By applying graded Gd-Tb alloy along the flow direction, the performance of magnetic refrigeration improves significantly. Compared to a pure Gd AMR system, it is demonstrated that more than three times the increase in the cooling capacity can be achieved.https://www.mdpi.com/1996-1073/18/2/289AMRCOMSOLduty cyclemagnetic refrigeratormagnetic field |
| spellingShingle | Chih-Hao Lee Pai-Hsiang Cheng Keh-Chyang Leou Chih-Ming Hsieh Yu-Chuan Su Calculation of the Optimal Magnetic Duty Cycle for a Graded Coaxial Magnet of a Rotary Type Magnetic Refrigerator Energies AMR COMSOL duty cycle magnetic refrigerator magnetic field |
| title | Calculation of the Optimal Magnetic Duty Cycle for a Graded Coaxial Magnet of a Rotary Type Magnetic Refrigerator |
| title_full | Calculation of the Optimal Magnetic Duty Cycle for a Graded Coaxial Magnet of a Rotary Type Magnetic Refrigerator |
| title_fullStr | Calculation of the Optimal Magnetic Duty Cycle for a Graded Coaxial Magnet of a Rotary Type Magnetic Refrigerator |
| title_full_unstemmed | Calculation of the Optimal Magnetic Duty Cycle for a Graded Coaxial Magnet of a Rotary Type Magnetic Refrigerator |
| title_short | Calculation of the Optimal Magnetic Duty Cycle for a Graded Coaxial Magnet of a Rotary Type Magnetic Refrigerator |
| title_sort | calculation of the optimal magnetic duty cycle for a graded coaxial magnet of a rotary type magnetic refrigerator |
| topic | AMR COMSOL duty cycle magnetic refrigerator magnetic field |
| url | https://www.mdpi.com/1996-1073/18/2/289 |
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