New Refrigeration Technologies on Environmental Test Chamber(2/2)

III. Magnetic refrigeration
Magnetic refrigeration (also known as the Magnao-Caloric Effect) refers to refrigeration with the magneto-caloric effect. The magnetic refrigeration working medium emits heat to the outside when the isothermal magnetization is magnetized, and the heat is absorbed from the outside when the magnetic refrigeration working medium is thermally insulated. In contrast to the ferromagnetic material, the magnetic thermal effect is the most sensible cooling characteristic in the vicinity of the Curie temperature (temperature of the magnetic order-disorder transition). When the external magnetic field is applied, the magnetic entropy value of the material is reduced and the heat is released; on the contrary, when the external magnetic field is removed, the magnetic entropy value of the material is increased and the heat is absorbed

IV. thermoacoustic refrigeration In brief, that thermoacoustic effect is a physical phenomenon that cause the acoustic self-oscillation of the heat in the elastic medium (often high-pressure inert gas). The thermoacoustic inverse effect can be used to heat the heat from a low temperature to a high temperature by means of an acoustic wave (alternating mechanical energy). When the high-temperature end is fixed at the ambient temperature, the temperature of the low-temperature end can be continuously reduced to realize the function of refrigeration.

V. Geothermal refrigeration The heat pump is mainly used for extracting a large amount of low-temperature-level heat (or cold energy) from the shallow ground energy (soil, ground water or surface water) through a heat pump, and the extracted heat is lifted from the low-temperature position to the high-temperature position by the heat pump system, so that the user can supply the winter heating, Summer cooling air-conditioning, full-year hot water supply or cooling air-conditioning.

VI. Laser refrigeration There are two methods for laser cooling at this stage: Doppler refrigeration technology and anti-Stokes fluorescence refrigeration technology.
1. Doppler refrigeration technology: all the molecules and atoms around us are subjected to a regular thermal movement which is never stopped, and the temperature is a physical quantity which is characterized by the intensity of such thermal movement. The higher the temperature, the more violent the heat movement, and vice versa. By reducing the intensity of the overall thermal motion of these molecules or atoms. The principle of the Doppler cooling technique is to block the thermal movement of the atoms by emitting the photons through the laser, so as to achieve the purpose of cooling the object.
2. The anti-Stokes fluorescence refrigeration is a new concept of refrigeration. Its basic principle is the anti-Stokes effect, and uses the energy difference of the scattering and the incident light to realize the refrigeration. The anti-Stokes effect is a special scattering effect whose scattering fluorescence photon wavelength is shorter than that of the incident light. Thus, the scattered fluorescent photon energy is higher than the incident light sub-energy. The process can be simply understood as follows: the light-emitting medium is excited by a low-energy laser photon, the light-emitting medium is scattered with a high-energy photon, and the original energy in the light-emitting medium is taken out of the medium and is cooled. Compared with the traditional refrigeration mode, the laser plays the role of providing refrigeration power.

With the rapid increase of the global population, the living standard has been rising, the lack of resources has become more and more obvious, and the environment is deteriorating. There has been abroad consensus on the protection of the environment and resources in the global context. refrigeration, as an integral part of human production, The most important problem for the development of refrigeration technology lies in the continuous improvement of its environmental protection and energy-saving performance. At present, the development of all kinds of new type of refrigeration technology has been developing rapidly, although it has not been widely used, its superiority has been affirmed, and the application of small range has become more and more common. The research and development department of Shanghai Forest-frequency Instrument has carried out the deep-level research on the low-temperature technology and applied the new technology to the environment test box. It is foreseen that the research and development of the new type of refrigeration technology will greatly promote the development of the environmental test equipment industry and the improvement of people‘s living standard.