Liquid nitrogen can be used in refrigeration, aviation, scientific research, medical and other industries.

Liquid nitrogen is a very common refrigerant in life. Because the main component is nitrogen, and nitrogen is a non-toxic and harmless gas, it is widely used in life.

1. What is liquid nitrogen?

Liquid nitrogen refers to nitrogen in a liquid state. Liquid nitrogen is an inert, colorless, odorless, non-corrosive, non-flammable, extremely low-temperature liquid. When liquid nitrogen vaporizes, it will absorb a lot of heat and reduce the surrounding temperature. Nitrogen makes up the majority of the atmosphere (78.03 by volume and 75.5 by weight). Under normal pressure, the boiling point of nitrogen is -196.56°C, and 1 cubic meter of liquid nitrogen can expand to 696 cubic meters of pure gaseous nitrogen (21°C). If pressurized, liquid nitrogen can be obtained at higher temperatures. In industrial production, liquid nitrogen is obtained by the fractionation of air. The air is first purified with a purifier, and then liquefied under pressurized and cooled conditions. Due to the different boiling points of each component in the air, the air is separated. There is no problem when human skin is in direct contact with liquid nitrogen for a moment, but once the time exceeds 2 seconds, it will cause frostbite.

2. The purpose and use of liquid nitrogen.

In the medical field, because many drugs need to be stored at low temperatures for a long time, the container containing the drugs can be placed in a liquid nitrogen tank to cool down. In the food processing industry, in order to maintain the original flavor of the food, liquid nitrogen is also used for rapid cooling to ensure the taste of the food to the greatest extent. In the aerospace field, liquid nitrogen generates ultra-high pressure when it vaporizes, so it can be used as a propulsion gas to push the engine forward. Liquid nitrogen can also be used for artificial rainfall activities. As long as liquid nitrogen is sprayed into dark clouds, the cold air can condense into raindrops. When we use liquid nitrogen, we should pay attention to using professional cold-proof gloves. Once direct contact with liquid nitrogen for a long time will lead to frostbite.