Analysis and processing of mechanical losses in Screw Compressors

The purpose of the Project is to estimate the mechanical losses in a screw compressor due to friction in the bearings and analyse how individual components affect the overall compressor performance. In particular, this study is focused on the Kirloskar 231mm Oil-flooded Twin Air Screw Compressor with a nominal power of 140kW and its bearings: NU213ECP, NU211ECP, NU1009ECP, 7311BEP and 7211BEP. The frictional moment and power consumption are predicted using the following three existing models: SKF, Harris, and Palmgren. According to all the models, it is concluded that the NU1009ECP bearing, at the suction of the female rotor contributes the least to the overall performance of the rotating machine. The 7311BEP bearing at the discharge of the male rotor appears to have the most impact on the efficiency of the bearing operation. The bearing sizes and the loads applied are the key factors contributing to these results. Furthermore, the power losses due to the friction in the bearings are 766.854W, 302.657W and 588.913W according to SKF, Palmgren and Harris models, respectively. The bearings are responsible for 0.548% of the overall power loss in the compressor package, which is 10.96% of the mechanical losses. The results are compared to the experimental data, which conclude that the SKF Model is the most accurate and precise estimation, while the Palmgren Model is found to be the most accurate in terms of the trajectory of the graph.