【摘要】 鉴于活性蓄冷器作为室温磁制冷核心部件,建立了活性蓄冷器二维复杂多孔介质模型,采用分子场理论计算励(退)磁过程磁性工质温度及磁熵变化,考虑了非Darcy效应、驻留流体、两相热扩散效应、热流边界效应及流体物性非定常的影响.采用有限差分法对两相能量方程进行离散求解.通过计算结果与实验结果的比较对模型进行了验证,认为所建模型能有效反映蓄冷器运行规律并模拟其内部温度分布.数值模拟结果显示:磁场强度变化为2.18 T条件下蓄冷器内金属Gd在其居里点处的温度改变为1.85 K;蓄冷器内部温度梯度明显,微元循环存在显著复叠现象;热流边界效应会导致蓄冷器制冷性能下降,流量较大时物性参数对制冷性能影响较大;在壁面热流通量为5 W/m2的条件下,蓄冷器获得的最大制冷量为201.8 W,对应性能系数为4.79.更多还原

【Abstract】 A two-dimensional complicated porous media model for an active magnetic regenerator of room temperature magnetic refrigeration was established.In the model,the molecular-field theory was adopted to calculate the temperature and magnetic entropy of magnetic material in magnetization(demagnetization) process and the influence of non-Darcy effect,water stored,thermal dispersion effect,heat flux boundary effect and variable fluid physical properties on numerical results was considered.The finite difference method was used to discretize and solve the two-phase energy equations.The present model was verified by experimental results.The numerical results show that the temperature change of Gd at its Curie temperature was 1.85 K under a magnetic field of 2.18 T;distinct temperature grades and overlapping phenomenon of infinitesimal element cycles existed in the regenerator;heat flux boundary effect reduced the refrigeration performance of the regenerator,and fluid physical properties influenced the refrigeration performance of the regenerator greatly at large fluid flux;the regenerator obtained a maximum refrigeration capacity of 201.8 W with a corresponding coefficient of performance of 4.79.更多还原