What are the materials in frozen saline?
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What are the materials in frozen saline? What else is there besides ethylene glycol? ?
Frozen saline is generally prepared using NaCl or CaCl2 (it seems that MgCl2 is also used sometimes). Industrially, temperatures of –5°C and –15°C are commonly used, while at –40°C only CaCl2 can be used for its preparation. The concentration must be adjusted properly to prevent crystallization. Once crystallized, it cannot be altered, as its freezing point and melting point are different. (One prepared with ethylene glycol cannot be called cryogenic saline; it can only be referred to as a coolant.) You can ask some experienced workers for the specific details; I’m not too sure either. ）
Calcium chloride solution is still the most commonly used one at present. Generally, when the outlet temperature of the coolant is at -15 degrees Celsius or lower, it is required that the specific gravity of the solution be no less than 1.20. However, the biggest problem with calcium chloride solutions is pipeline corrosion; for this reason, ethylene glycol is now used as a refrigerant in some applications
Chilled water above 0°C can be used directly； -Chilled water above 7℃, using NaCl solution ； -A CaCl2 solution is used for chilled water at around 20°C. Anything related to this (that I have used or seen) should be included in any book on refrigeration. “If one is going to switch to working in enterprises where such things are used, it’s best to understand the types of refrigerators as well as the potential problems that may arise during their use; it’s useful to gain knowledge on these aspects in a targeted manner. For example, the quality of cooling water is key to improving refrigeration efficiency; how can we improve water quality in a simple and effective way? For reference.
Frozen methanol water, with a methanol content of around 28%, can be cooled to -8°C without any problem.
Our company uses ethylene glycol; the lowest condensation temperature is -40°, and its components should be ethylene glycol and water!
If the temperature is below -30°C, it is recommended to use a calcium chloride solution, as a high concentration of ethylene glycol at such temperatures increases the resistance in the piping system.
Using a calcium chloride aqueous solution is cost-effective; generally, large chemical companies use such solutions for their refrigeration systems. For smaller-scale cooling applications, an ethylene glycol aqueous solution can be considered. As mentioned by the friend above, methanol aqueous solutions are rarely used, but they can be employed as a last resort.