A magnetic refrigerator is an environmentally friendly refrigeration device that uses the magnetocaloric effect (MCE) to achieve cooling, replacing traditional vapor-compression refrigeration technologies that rely on ozone-depleting refrigerants (e.g., CFCs) or high-greenhouse-effect gases (e.g., HFCs). The magnetocaloric effect refers to the phenomenon where a magnetic material heats up when placed in a magnetic field (due to the ordered arrangement of magnetic domains) and cools down when the magnetic field is removed (due to the disordered arrangement of magnetic domains). With advantages such as high energy efficiency (20-30% higher than traditional refrigerators), low noise, and no harmful emissions, magnetic refrigerators are considered a key direction for the future development of refrigeration technology, with applications in household refrigeration, industrial cooling, and aerospace temperature control.

The core components of a magnetic refrigerator include a magnetocaloric material (MCM), magnetic field generation system, heat transfer system, and cycle control mechanism. Magnetocaloric materials are the core of the refrigeration process—common materials include rare-earth-based alloys (e.g., Gd5Si2Ge2, gadolinium-doped alloys) and perovskite oxides. These materials have a strong magnetocaloric effect near room temperature: when a magnetic field (generated by permanent magnets or superconducting magnets) is applied, their temperature rises by 5-10°C; when the magnetic field is removed, their temperature drops by the same range. The heat transfer system uses a heat transfer fluid (e.g., water or helium gas) to absorb the heat generated by the MCM in the magnetic field (and release it to the outside environment) and transfer the cold energy generated when the magnetic field is removed to the refrigeration chamber. The cycle control mechanism (e.g., a rotating mechanism or linear actuator) alternates the MCM between the magnetic field and non-magnetic field regions, realizing continuous cooling.

The working cycle of a magnetic refrigerator typically follows four steps: magnetization, heat rejection, demagnetization, and cold absorption. In the magnetization step, the MCM enters the magnetic field, its magnetic domains are ordered, and temperature rises. In the heat rejection step, the heat transfer fluid flows through the MCM, absorbing the generated heat and releasing it to the outside (via a radiator). In the demagnetization step, the MCM leaves the magnetic field, its magnetic domains are disordered, and temperature drops below the ambient temperature. In the cold absorption step, the low-temperature heat transfer fluid flows into the refrigeration chamber, absorbing the heat in the chamber to achieve cooling. This cycle repeats continuously, maintaining the low temperature of the refrigeration chamber.

Although magnetic refrigeration technology is still in the industrialization stage, it has shown great application potential. In household refrigeration, prototype magnetic refrigerators developed by companies like Astronautics Corporation of America (ACA) have achieved a cooling capacity of 500W, with an energy efficiency ratio (EER) of 4.5 (compared to 3.0-3.5 for traditional refrigerators), and can reduce carbon emissions by 30% during use. In industrial cooling, magnetic refrigerators are used to cool high-power electronic devices (e.g., computer servers and power semiconductors)—their low-noise and high-efficiency characteristics ensure stable operation of the equipment. In aerospace, magnetic refrigerators are suitable for space stations and satellites, as they do not rely on moving parts like compressors (which are prone to failure in microgravity environments) and can operate reliably for a long time. With the continuous improvement of magnetocaloric materials and magnetic field systems, magnetic refrigerators are expected to replace traditional refrigeration equipment on a large scale in the next 10-20 years.