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Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Highway MC 338 tanks are used for the transportation of cryogenic gases, sometimes referred to as refrigerated liquids (Figure 3.95). These materials are very cold with boiling points of −130 for carbon dioxide to −452 for liquid helium. Common cryogenics include oxygen, nitrogen, helium, argon, and others. Many of the materials carried in 338 tanks are considered inert gases. That is to say, they do not readily react chemically to other materials, are not flammable and are nonpoisonous. They do, however, have significant hazards when released as a liquid or a gas. Liquids are extremely cold and can cause frostbite and solidification of anything it contacts including body parts. They have large expansion ratios, producing huge amounts of vapor from a small spill. In some cases, as little as 1 gallon of a cryogenic liquid can produce over 900 gallons of gas. Although these gases are inert in many cases, they can still displace the oxygen in the air and cause simple asphyxiation.
Common Sense Emergency Response
Published in Robert A. Burke, Common Sense Emergency Response, 2020
MC 338 tanks (Figure 4.16) are used for transporting cryogenic gases, sometimes referred to as refrigerated liquids. These materials are very cold with boiling points of −130°F for carbon dioxide to −452°F for liquid helium. Common cryogenics include oxygen, nitrogen, helium, argon, and others. Many of the materials carried in 338 tanks are considered inert gases. That is, they do not readily react chemically to other materials, are not flammable, and are not poisonous. They do, however, have significant hazards when released as liquids or gases. Liquids are extremely cold and can cause frostbite and solidification of anything they contact, including body parts. Liquids also have large expansion ratios, producing huge amounts of vapor from the small spill. In some cases, as little as 1 gallon of a cryogenic liquid can produce over 900 gallons of gas. While these gases are inert in many cases, they can still displace the oxygen in air and cause simple asphyxiation.
Cryogenic Cooling Strategies
Published in Raja Sekhar Dondapati, High-Temperature Superconducting Devices for Energy Applications, 2020
Sudheer Thadela, Raja Sekhar Dondapati
A crucial role is played by thermal conductivity in the selection of materials. Materials such as copper, brass, stainless steel, glass, epoxy composites, KaptonTM, and TeflonTM of various grades are widely used for cryogenic applications. In general cases, thermal conductivity depends on the purity of the material. At cryogenic temperatures, higher purity metals possess higher thermal conductivities. In metals, purity is represented in terms of residual resistance ratio (RRR) of standard temperature and pressure (STP) to 4.2 K (RRR→R293 K/R4.2 K). At room temperature, the thermal conductivity in metals is mostly due to the vibration of lattice; however, temperature below 77 K is dominated by the effects of defects and impurities.
A review on sustainable alternatives for conventional cutting fluid applications for improved machinability
Published in Machining Science and Technology, 2023
D. J. Hiran Gabriel, M. Parthiban, I. Kantharaj, N. Beemkumar
The term cryogenics is associated with the study of the production of fluids at extremely low temperatures and the properties of those materials at that temperature. Gases are liquefied and used as a coolant during metal cutting. Such a cooling technique is referred to as cryogenic cooling. Potential liquid cryogens include nitrogen (N2), carbon dioxide (CO2), and helium (He). This cryogenic liquid, when introduced to the zone of metal cutting, evaporates quickly, creating a gaseous layer between the material to be machined and the cutting face of the tool. The gaseous layer generated as a result of the liquid’s evaporation works as a lubricant. Cryogenic machining is a relatively new technique in the machining process. This approach was used in a variety of machining techniques, such as turning, milling, and drilling. Cryogenic machining is often used on superalloys (such as titanium alloys, Inconel alloys, and tantalum alloys), ferrous metals, viscoelastic polymers, and elastomers. In general, desirable results have been obtained no matter what kind of workpiece materials were used (Dhananchezian and Kumar, 2011).
A Critical Review on Mechanical Heat Switches for Engineering and Space Applications
Published in Heat Transfer Engineering, 2022
Banka Raghu Ram, Vinit Malik, Bukke Kiran Naik, Kishore Singh Patel
The previously discussed categorization of MHS, GGHS, SCHS, and MRHS is based on their functioning. However, these heat switches can also be subclassified in several other ways. One of the major classifications is based on their operating temperature range. For example, the MHS can operate in both cryogenic temperature and normal/room temperature range. The classifications of MHS based on their operating range can be seen in Figure 1(a). As can be seen, temperature range-based classification starts from absolute zero (0 K) to 123 K for the low/cryogenic temperature range, and normal temperature ranges cover above 123 K [18]. The term cryogenics is derived from the Greek words "kryos" (frost) and "genics" (to produce). The term cryogenics means the production and behavior of the material at ultra-low temperatures. The temperature range-based classification helps identify the appropriate heat switches which can be operated in the chosen temperature range as different material shows their transition from gas to liquid and liquid to solid state at different temperatures.
A comparative analysis of grinding of AISI D2 tool steel under different environments
Published in Machining Science and Technology, 2022
Ashwani Sharma, Mohd Zaheer Khan Yusufzai, Meghanshu Vashista
Cryogenic coolants have a broad category of applications in industries such as manufacturing, aerospace, automotive, electronics and the health industry, especially for cooling purposes. The cryogenic coolant is commonly liquid nitrogen (LN2) that is condensed by boiling to −196 Nitrogen (N2) gas is a colorless, odorless, tasteless, nontoxic and non-flammable gas. In fact, about four-fifths (78.03%) of the air, N2 gas is present in the atmosphere. In a cryogenic grinding process, the evaporation of LN2 is very fast and reverts to the air (Yildiz and Nalbant, 2008). During material removal processes in the grinding operation, cryogenic grinding is the most suitable technique for cooling the grinding wheel or workpiece or wheel-workpiece interface.