Performance study of a double-regenerator room temperature magnetic refrigerator with 26 °C temperature span

Magnetic refrigeration (MR) has the characteristics of green environmental protection, high energy efficiency and reliable operation, which is expected to replace gas compression refrigeration in the future. Based on the principle of MR, Baotou Research Institute of Rare Earths (BRIRE) successfully developed a practical room temperature magnetic refrigerator with two regenerators. The performance of the magnetic refrigerator in different environments was studied, and the velocity distribution of the fluid in regenerator together with the temperature span between the cold end and hot end were analyzed by numerical calculation. The magnetic refrigerator is mainly composed of a refrigeration chamber, two regenerators, magnetic field system, valves, a pump and so on. The magnetic field system consists of two sets of double-layer annularly nested NdFeB permanent magnetic arrays, which can accommodate two regenerators. The magnetization and demagnetization of magnetic refrigerant are realized by the rotation of the inner magnetic array, and the range of generated magnetic field is 0-1.4 T. The magnetic refrigerator adopts 2 kg spherical Gd particles as magnetic refrigerant and water as heat exchange fluid, and the cycle frequency is 0.25 Hz. When the cold end is equipped with a 117 L refrigeration chamber at ambient temperature of 22 °C, the temperature of refrigeration chamber can reach 8 °C, and the refrigeration temperature span is 26 °C, which meets the requirement of the market for refrigeration. The maximum cooling power of the magnetic refrigerator measured by compensation method is 100 W. The simulation results of the temperature of flow and cold end are in good agreement with the experimental results.