Some of the refrigeration units have enough space within the condenser to accommodate the entire refrigerant charge of the system. If the condenser does not have sufficient space, a receiver tank should be provided. The amount of refrigerant required for proper operation of the system determines whether or not a receiver is required. In practice, when proper unit operation requires approximately 3.6 kg or more of refrigerant, the use of a receiver is essential (Langley, 1982).
Receivers (Figure 3.25) are required on refrigeration systems which use an expansion valve for refrigerant control. The receiver provides a place to store the excess refrigerant in the system when the expansion valve restricts the flow to the evaporator. Receivers are not required, however, when using a capillary metering system. In addition to accommodating fluctuations in the refrigerant charge, the receiver aims to maintain the condenser drained of liquid, thereby preventing the liquid level from building up in the condenser and reducing the amount of effective condenser surface area.