Secondary Refrigerant

Refrigerant, Secondary

 

(also secondary coolant), a liquid or gas that is used in refrigerating systems as an intermediate medium for heat transfer from the object to be cooled to the refrigerant, which boils in the evaporator of the refrigerating machine. Systems that operate with secondary refrigerants are used in cases where the direct cooling of an object by means of a boiling refrigerant is impossible, difficult, or uneconomical, for example, when there are many users or when the users are far from the machine room.

Secondary refrigerants should have a low freezing point, a low viscosity, a high specific heat, and a high thermal conductivity. They should be nontoxic, flameproof, and neutral with respect to building materials.

Solutions of salts in water, called refrigeration brines, are used as secondary refrigerants. Sodium chloride brine is employed for temperatures down to – 15°C; magnesium chloride brine, down to – 27°C; and calcium chloride brine, down to – 45°C. Antifreezes and Freons are used in low-temperature refrigerating systems. Aqueous solutions of propylene glycol are employed for temperatures down to – 47°C; aqueous solutions of ethylene glycol, down to – 60°C; Freon-30, down to – 90°C; and Freon-11, down to – 100°C.

Water is used as the secondary coolant in air-conditioning systems.

V. A. GOGOLIN

References in periodicals archive ?
Contract notice: maintenance of secondary refrigerant networks and refrigeration equipment specific to an individual installation.
2] was previously used solely as the secondary refrigerant in ice rinks, but C[O.
The Kuehne+Nagel system features two air-cooled Azanechillers with ammonia as primary and glycol as secondary refrigerant.
The secondary refrigerant mass flow rate used to produce the subcooling in the main current of refrigerant in the high-pressure line is obtained indirectly from an energetic balance at the subcooler using Equation 1 with the nomenclature of Figure 2.
However, using glycol as a secondary refrigerant means that primary refrigerants are contained within the external refrigeration plant, in this case a glycol chiller, while a safe glycol solution is circulated within the pipe work connecting the outdoor chiller to the blast coolers in the room.
Since the medium-temperature secondary refrigerant (propylene glycol) is not under high pressure like primary refrigerant in a direct expansion system, ABS plastic piping was used in the Williamsburg store.
Most ice rinks in recent years have been built as indirect systems using a secondary refrigerant.
Water is been used by the system as its secondary refrigerant.
The Culina system features two AA750 air-cooled Azanechillers with ammonia as primary and glycol as secondary refrigerant.
With Second Nature systems, refrigerated display cases and walk-in coolers/freezers are redesigned to benefit from the latest advances in secondary refrigerant technology.