Bitzer ST-140-1 Mode D'emploi page 43

1 Introduction
In case of high thermal load of compressors, additional cooling is required. For screw compressors, oil cooling is of-
ten used for this purpose: The use of an external oil cooler is universally possible and allows operation with exten-
ded application limits and high efficiency. The following options are described in this document:
• air cooled external oil coolers
• water cooled external oil coolers
• refrigerant cooled external oil coolers (thermosiphon oil cooling)
[bar]
Condensation
Evaporation
Fig. 1: Influence of oil cooling on the discharge gas temperature in the log-p-h diagram. The discharge gas temperature can thus be reduced
e.g. from 140°C to 80°C.
As an alternative to oil cooling, liquid injection will be briefly mentioned. However, this technique is limited to a relat-
ively low refrigerating capacity due to the risk of oil dilution (see BITZER Software).
Also observe the following technical documents
SB-100 : Operating Instructions Semi-hermetic screw compressors HS.53 .. 74
SB-110 : Operating Instructions Semi-hermetic screw compressors HS.85 .. 95
SB-160 : Operating Instructions Semi-hermetic screw compressors with integrated frequency inverter CSV.
SB-170 : Operating Instructions Semi-hermetic compact screw compressors CS.
SB-500 : Operating Instructions Open drive screw compressors OS.53 .. 74
SB-510 : Operating Instructions Open drive screw compressors OS.85
SB-520 : Operating Instructions Open drive screw compressors for NH
DB-200-5 : Operating Instructions Pressure vessels: Water-cooled condensers and oil coolers (OW401(B) .. 941(B))
AT-640 : Use of ammonia (R717) in BITZER compressors
ST-500 : BITZER refrigeration compressor oils for compact screw compressors CS., CSV.
ST-610 : Economiser operation of screw copressors
ST-140-1 // PDF Download
Effect of
oil cooling
[kJ/kg]
3
applications OS.A95
43