旋转式室温磁制冷机用永磁系统的设计与数值计算

Design and numerical simulation of magnetic field system for rotary room�temperature magnetic refrigerator

选用NdFeB永磁体提供磁场以及高磁导率钢作为磁轭,设计旋转式室温磁制冷机用永磁系统,并利用有限元法计算磁场分布。设计的永磁系统可利用距离控制架调节NdFeB永磁体的位置,从而实现空间磁场范围内的连续可调。永磁系统中间部分由电机带动做定轴转动,以实现磁工质的励磁与退磁。利用COMSOL Multiphysics软件对磁工质所在位置的磁场进行数值计算。结果表明:距离L的减小导致磁感应强度的最大值B1增大,最小值B2减小,致使磁场强度范围变大,增强磁工质的磁热效应;当L为79 mm时,不同旋转角度α下,永磁系统所产生的磁场强度范围为32~1265 mT;并且,磁感应强度值的实测结果和计算结果吻合程度较好,差值在30 mT以内。

A magnetic field system for rotary room-temperature magnetic refrigerator was designed.The NdFeB magnets were used to provide magnetic field and high permeability steel was used as magnetic yoke.The distribution of magnetic field was simulated by finite element analysis.In the designed magnet field system,the relative position of NdFeB magnets can be adjusted by using the distance control frame to realize the continuous adjustment of the magnetic field in the spatial range.A motor drives the middle part of magnetic field system to rotate to realize the excitation and demagnetization of the magnetic refrigerant.The COMSOL Multiphysics software was used to simulate the magnetic field at the position of magnetic refrigerant.The simulation results demonstrate that the decrease of distance(L)will increase the maximum magnetic induction intensity B1 and decrease the minimum magnetic induction intensity B2,which expands the range of magnetic field intensity and enhances the magnetocaloric effect of magnetic refrigerant.Under different degrees of rotation(α),the magnetic field intensity generated by the magnetic field system ranges from 32 mT to 1265 mT when L=79 mm.The measurement result of magnetic induction intensity is in good agreement with the simulation.The difference between them is within 30 mT.