a single assembly containing all or some of the components of a refrigerating machine. A refrigerating unit has a common frame or a common chassis. In some cases, the unit is mounted on one of its components or subassemblies; in such cases, the component (usually a heat exchanger) on which the unit is mounted should be heavy enough and large enough that all the other components may be mounted on it.
Refrigerating units are assembled in factories to ensure that the assembly, sealing, cleaning, and drying of the units are of considerably higher quality than in the case where unassembled refrigeration equipment is assembled at the facility where it is used. When refrigerating units are delivered, they are already filled with a refrigerant or with a nonreactive gas, such as nitrogen; units containing a compressor are also filled with lubricating oil. The installation of a refrigerating unit entails the mounting of the unit on a foundation, if one is required, and the connection of the unit to refrigerant and water-service pipes and to electricpower mains.
Refrigerating units should be compact, should have no protruding parts that are difficult to pack, and should be easy to disassemble. The components should be easy to repair, and the piping and fittings should be as short as possible. Servicing of the units from one side is desirable. Control panels, instrumentation, and automatic equipment are mounted on the side from which a unit is serviced.
All types of refrigerating machines—vapor-compression, absorption, steam-jet, and air-cycle—may be unitized. Domestic refrigerators and air conditioners are examples of the highest degree of unitization.
V. L. TSIRLIN