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How Does Liquid Nitrogen Stay Cool

Edit: Henan Tianchi Instrument Equipment Co., Ltd    Date:2018-05-14
1. The liquid nitrogen container is divided into two kinds with pressure and normal pressure. Atmospheric pressure means that there is no seal between liquid nitrogen and atmosphere. It is simply isolated. At this time, the temperature of liquid nitrogen is about 77 K.
2. How to keep such a low temperature?
Liquid nitrogen tanks have been used to store cells. Liquid nitrogen tanks are not "high pressure closed". Liquid nitrogen in liquid nitrogen tanks will vaporize and evaporate daily.
Reasons for keeping the temperature low: Liquid nitrogen takes away heat to keep the temperature low during gasification.
Another reason is that liquid nitrogen tanks are generally made of porous foam material, and their thermal conductivity is very low, effectively blocking the heat conduction at the outlet.
“Liquid nitrogen tanks increase the boiling point of liquid nitrogen by maintaining a high pressure and keep the nitrogen liquid. According to the laws of thermodynamics, the temperature in liquid nitrogen tanks should also be room temperature.”
In fact, so-called liquid nitrogen tanks do not rely solely on high-pressure closed environments to maintain nitrogen liquids, because nitrogen liquefaction has a critical temperature of -147°C, exceeding the critical temperature, no matter how much pressure is added, it cannot liquefy nitrogen, and the most important is the partition of liquid nitrogen. Because of the existence of a critical temperature in the heat conduction method, it is impossible to have normal-temperature liquid nitrogen.