A tank of liquid nitrogen, used to supply a cryogenic freezer (for storing laboratory samples at a temperature of about -150 Celsius). Cryopreservation is a process where cells or whole tissues are preserved by cooling to low sub-zero Temperatures such as (typically 77 K or −196

Liquid nitrogen may be used to prepare "home-made" ice cream, as these students are doing. Ice cream or ice-cream (originally iced cream) is a frozen dessert made from Dairy products such as Milk and Cream, combined

Liquid nitrogen boiling in a cup

Liquid nitrogen (liquid density at the triple point is 0. In Thermodynamics, the triple point of a substance is the Temperature and Pressure at which three phases (for example Gas, Liquid 707 g/mL) is the liquid produced industrially in large quantities by fractional distillation of liquid air and is often referred to by the abbreviation, LN₂. Fractional distillation is the separation of a mixture into its component parts or fractions such as in separating Chemical compounds by their Boiling point by heating Liquid Air was the brand name of an unusual Automobile produced by a joint American / English concern between 1899 and 1902 It is pure nitrogen, in a liquid state. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Liquid nitrogen has the UN number 1977. UN numbers or UN IDs are four-digit numbers that identify Hazardous substances, and articles (such as explosives flammable liquids toxic substances etc

Liquid nitrogen boils at 77 K (−196 °C/−321 °F), and is a cryogenic fluid which can cause rapid frostbite on contact with living tissue. Cryogenics is often used incorrectly to refer to Cryonics, cryopreserving humans or animals Frostbite ( congelatio in Medical terminology) is the Medical condition whereby damage is caused to Skin and other tissues It has a dielectric constant of 1. 4. ^[1] When appropriately insulated from ambient heat, liquid nitrogen can be stored and transported, for example in vacuum flasks. The term thermal insulation can refer to materials used to reduce the rate of Heat transfer, or the methods and processes used to reduce heat transfer In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Here, the very low temperature is held constant at 77K by slow boiling of the liquid, resulting in the evolution of nitrogen gas. Depending on the size and design, the holding time of vacuum flasks ranges from a few hours to a few weeks.

Liquid nitrogen can easily be converted to the solid by placing it in a vacuum chamber pumped by a rotary vacuum pump. ^[2] Liquid nitrogen freezes at 63 K (−210 °C/−346 °F). Despite its reputation, liquid nitrogen's efficiency as a coolant is reduced by the fact that it boils immediately on contact with a warmer object, enveloping the object in insulating nitrogen gas. This effect is known as the Leidenfrost effect and applies to any liquid in contact with an object significantly hotter than its boiling point. The Leidenfrost effect is a Phenomenon in which a liquid in near contact with a mass significantly hotter than its Boiling point, produces an insulating Vapor More rapid cooling may be obtained by plunging an object into a slush of liquid and solid nitrogen than into liquid nitrogen alone. That said, liquid nitrogen alone is sufficient for most applications.

Applications

Liquid nitrogen is a compact and readily transported source of nitrogen gas without pressurization. Further, its ability to maintain temperatures far below the freezing point of water makes it extremely useful in a wide range of applications, primarily as an open-cycle refrigerant, including:

• in cryogenics
• as a source of very dry nitrogen gas
• the immersion freezing and transportation of food products
• the cryopreservation of blood, reproductive cells (sperm and egg), and other biological samples and materials
• as a cooling supplement for overclocking a central processing unit, a graphics processing unit, or another type of computer hardware^[3]
• as a method of freezing water pipes in order to work on them in situations where a valve is not available to block water flow to the work area. Freezing Point (Chinese 冰點 Bīngdiǎn is a news journal in the People's Republic of China which has been the subject of controversy over its criticism A refrigerant is a compound used in a heat cycle that undergoes a Phase change from a Gas to a Liquid and back Cryogenics is often used incorrectly to refer to Cryonics, cryopreserving humans or animals Food is any substance usually composed primarily of Carbohydrates Fats water and/or Proteins that can be eaten or drunk by an Cryopreservation is a process where cells or whole tissues are preserved by cooling to low sub-zero Temperatures such as (typically 77 K or −196 Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells ��such as nutrients and oxygen—and transports Waste products The term sperm is derived from the Greek word (σπέρμα sperma (meaning "seed" and refers to the male reproductive cells. An ovum (plural ova) is a Haploid Female reproductive cell or Gamete. Foundations of modern biology There are five unifying principles Typical PC hardware A typical Personal computer consists of a case or chassis in a tower shape (desktop and the following parts Motherboard
• in cryotherapy for removing unsightly or potentially malignant skin lesions such as warts and actinic keratosis. Cryotherapy is the use of cold in a variety of modalities to treat a medical condition Skin cancer is a Malignant growth on the Skin which can have many causes A wart (also known as verruca) is generally a small rough Tumor, typically on hands and feet but often other locations that can resemble a Cauliflower Actinic keratosis (also called solar keratosis, or AK) is a Premalignant condition of thick scaly or crusty patches of skin
• in the process of promession, a way to dispose of the dead. Promession is an ecologically -conscious method for disposing of human remains by Freeze drying.
• cooling a high-temperature superconductor to a temperature sufficient to achieve superconductivity. High-temperature superconductors (abbreviated high Tc or HTS) are a family of superconducting Ceramic materials largely Superconductivity is a phenomenon occurring in certain Materials generally at very low Temperatures characterized by exactly zero electrical resistance
• the cryonic preservation of humans and pets in the hope of future reanimation. Cryonics is the low-temperature Preservation of Humans and other Animals that can no longer be sustained by contemporary Medicine until
• as a coolant for vacuum pump traps and in controlled-evaporation processes in chemistry. A vacuum pump is a device that removes gas molecules from a sealed volume in order to leave behind a partial Vacuum. A rotary evaporator (or rotavap) is a device used in Chemical laboratories for the efficient and gentle removal of Solvents from samples by Evaporation

Safety

Since the liquid to gas expansion ratio of this substance is 1:694,^[4] a tremendous amount of force can be generated when liquid nitrogen boils off for whatever reasons. In a well-known accident in 2006 at Texas A&M University, the pressure-relief devices of a tank of liquid nitrogen were sealed with brass plugs. Texas A&M University, often called A&M or TAMU, is a Coeducational public Research University located in College Station As a result, the tank failed catastrophically, and exploded. The force of the explosion was sufficient to propel the tank through the floor/ceiling immediately above it. ^[5]

Due to its extremely low temperature, careless handling of liquid nitrogen may result in cold burns. A burn is a type of Injury that may be caused by Heat, cold, Electricity, Chemicals, Light, Radiation, or It should be also borne in mind, that as liquid nitrogen evaporates it will reduce the oxygen concentration in the air and might act as an asphyxiant, especially in confined spaces. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five Nitrogen is odourless, colourless and tasteless, and may produce asphyxia without any sensation or prior warning. ^[6]

Vessels containing liquid nitrogen can condense oxygen from air. The liquid in such a vessel becomes increasingly enriched in oxygen (boiling point = 90 K) as the nitrogen evaporates, and can cause violent oxidation of organic material.

See also

• Computer cooling
• Liquid nitrogen economy

References

1. ^ [[www. Computer cooling is the process of removing heat from computer components A liquid nitrogen economy is a hypothetical proposal for a future Economy in which the primary form of energy storage and transport is Liquid nitrogen. apgsensors. com/ltr2/access. php?file=pdf/dielectric-constants. pdf] Dielectric Constants].
2. ^ Umrath, W. (1974) Cooling bath for rapid freezing in electron microscopy. Journal of Microscopy 101, 103–105.
3. ^ Wainner, Scott; Robert Richmond (2003). The Book of Overclocking: Tweak Your PC to Unleash Its Power. No Starch Press, p. 44. ISBN 188641176X.  
4. ^ Information Specific to Liquid Nitrogen. Harvard University (30 Jul 03).
5. ^ Brent S. Mattox. Investigative Report on Chemistry 301A Cylinder Explosion (reprint). Texas A&M University.
6. ^ British Compressed Gases Association (2000) BCGA Code of Practice CP30. The Safe Use of Liquid nitrogen dewars up to 50 litres. ISSN 0260-4809. [1]

External Links

• Behind the scenes video - How liquid nitrogen is used in restaurants for cooking and cocktails