Brine is a common fluid used as a secondary refrigerant in large refrigeration installations for the transport of thermal energy from place to place. Being inexpensive, most common refrigerant brines are based on calcium chloride, sodium chloride and glycols.[1] It is used because the addition of salt to water lowers the freezing temperature of the solution and the heat transport efficiency can be greatly enhanced for the comparatively low cost of the material. The lowest freezing point obtainable for NaCl brine is −21.1 °C (−6.0 °F) at 23.3wt% NaCl.[1] This is called the eutectic point.
Sodium chloride brine spray is used on some fishing vessels to freeze fish.[2] The brine temperature is generally −5 °F (−21 °C). Air blast freezing temperatures are −31 °F (−35 °C) or lower. Given the higher temperature of brine, the system efficiency over air blast freezing can be higher. High-value fish usually are frozen at much lower temperatures, below the practical temperature limit for brine.
Because of the corrosive properties of salt-based brines, glycols such as polyethylene glycol, have become common for this purpose.[3]
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