Brine (refrigeration)
Brine (also cold brine or cooling brine ) is an aqueous solution with a freezing point below that of water.
use
In refrigeration technology , brine is used as a cooling liquid in order to prevent ice formation on heat exchangers or in pipes when the cooling water temperature is expected to be below 4 ° C. Cooling brines are used to transport cold from a central refrigeration system to various refrigeration consumers, e.g. B. in air conditioning systems , frozen food chains or technical refrigeration systems .
species
The name brine comes from the fact that salts ( chlorides or carbonates ) were used as antifreeze agents in the past . Because of the risk of corrosion from such salt solutions, especially in metal systems, predominantly glycols such as ethylene glycol or propylene glycol (1,2-propanediol) are used today; Corrosion inhibitors are also added to the glycol-water mixtures . When using glycol in refrigeration systems in food processing , only propylene glycol may be used. In the meantime, cooling brines are available that only contain substances that are permitted as food additives.
properties
Depending on the type of antifreeze and its concentration , the freezing point is reduced to different degrees :
- the lowest freezing point of a sodium chloride solution is at the eutectic point ( content of 23.4%) at −21.3 ° C.
- when using a 50/50 mixture with ethylene glycol as the cooling liquid, the freezing point drops to −38 ° C; at the same time be compared to pure water
- the heat transfer deteriorates
- the specific heat capacity reduced from 4.2 kJ / (kg K) to 3.5 kJ / (kg K)
- the viscosity of the coolant is increased, which results in increased pump performance.
literature
- Recknagel, Sprenger, Schramek: Pocket book for heating and air conditioning. 68th edition, R. Oldenbourg Verlag, Munich, Vienna 1997
Individual evidence
- ↑ Glysofor - heat transfer and coolant for the food industry
- ↑ Clariant - Heat Transfer Fluids ( Memento of the original from March 17, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
