A small but important vessel is the thermosyphon receiver which is an integral part of that type of oil cooling concept for screw compressors. The procedure for selecting the size of the thermosyphon receiver is explained in Sec. 5.14 and the key requirement is that it provides a reserve for five minutes of flow to the oil cooler if the supply of liquid from the condenser is interrupted. Separation of liquid and vapor indeed also takes place in the thermosyphon receiver, but the requirements are not stringent. Some liquid mist could pass through the vent line to the condenser inlet without an adverse effect, but it should be emphasized that the return of liquid and vapor from the oil cooler should not be delivered to the condenser inlet, because such a large fraction of liquid would degrade the condenser performance.
Some designers and contractors combine the thermosyphon receiver and the system receiver as shown in Fig. 10.16. Rather than transferring the liquid from a separate thermosyphon receiver to a separate system condenser, the liquid simply spills over from the oil cooler reserve into the system receiver.