Simulation of a hydraulic circuit for a magnetic refrigerator.

The flow distribution system plays a key role in the operation and the overall performance of a magnetic refrigerator, but only a few works in the literature are dedicated to the design and evaluation of it. Therefore, the focus of this work was to evaluate the transient behavior of a flow management system by means of numerical simulations of a simplified hydraulic circuit of the magnetic refrigerator developed at POLO/UFSC using a commercial software package. Water hammers were predicted to occur after switching the fluid flow direction, and their magnitude was proportional to the volumetric flow rate. The performance of the hydraulic system showed a dependence on the valve opening ramp; while fast ramps increased the magnitude of the water hammer, slow ramps led to fluid flow bypassing the AMR. The use of a proportional returning valve upstream of the high-pressure valves is recommended to absorb the impact of the water hammers and make the flow through the regenerator beds smoother.

流体分配系统在磁制冷机的运行与整体性能中发挥着关键作用，但现有文献中仅有少量研究致力于其设计与性能评估。因此，本研究的核心目标为：依托POLO/UFSC开发的磁制冷机简化液压回路，借助商用软件包开展数值模拟，以此评估流体管理系统的瞬态特性。研究预测，流体流向切换后会产生水锤（water hammer）现象，且其强度与体积流量呈正比关系。该液压系统的性能与阀门开启斜率紧密相关：快速斜率会加剧水锤强度，而缓慢斜率则会导致流体旁通主动磁再生器（Active Magnetic Regenerator，AMR）。建议在高压阀门上游加装比例回流阀，以缓冲水锤的冲击，使流经再生器床层的流体流动更为平稳。