In order to achieve an economical ultra-low temperature environment for glass reactors, many customers will not choose multi-stage compressor refrigeration equipment with more than two stages, but use liquid nitrogen. The cost of liquid nitrogen is low, and this refrigeration method is welcomed by some users, both in experiments and in production. However, due to the low boiling point of liquid nitrogen (minus 195.8°C), the latent heat is small and it is easy to evaporate. There are also big problems with using liquid nitrogen refrigerators safely.
In the storage, transportation and application of liquid nitrogen, it is necessary to have storage and application equipment with good thermal insulation performance. Most of the liquid nitrogen related equipment and pipeline fittings on the market adopt double-walled vacuum container structure. The key factor affecting the performance of this vacuum container and accessories is the vacuum degree of the interlayer. Moreover, the use of liquid nitrogen puts forward higher requirements on the reactor temperature control method, heat preservation measures, material properties, equipment sealing and pressure control, and environmental safety measures. Glass reactors cooled with liquid nitrogen must still retain the advantage of being transparent and visible during the reaction. Moreover, liquid nitrogen is a health hazard: skin contact with liquid nitrogen can cause frostbite. If the nitrogen produced by vaporization under normal pressure is excessive, the partial pressure of oxygen in the air will drop, causing hypoxia and suffocation. Guanya Refrigeration's ultra-low temperature freezer adopts the single-machine cascade refrigeration process, and the low temperature can reach minus 150 degrees; it adopts the secondary supercooling technology, and the refrigeration is rapid.