Energy Efficiency of an Oil Injected Screw Compressor Operating at Various Discharge Pressures

The oil injected-screw compressor is a volumetric machine with positive displacement that achieves the compression by gradually reducing the volume of gas trapped between two helical meshing rotors and the casing. For those compressors with fix volume ratio the theoretical discharge pressure represents the pressure that will be obtained in the compressor independently of the system discharge pressure. This level of pressure will also determine the energy consumption for the compression. The experimental research presented by the paper was performed on COMOTI test bench and it reveals that by reducing the pressure in the discharge main line below the value of the theoretical pressure obtained by the compressor internal pressure, there will be also obtained lower levels of the energy consumption. The authors concluded that the reduction in energy consumption occurs due to gas losses from the compression chamber into the discharge pipe, due to pressure differences.