Dynamic characteristics improvement of the single screw compressor with odd-grooves screw rotor

Abstract

Recently, the single screw compressor (SSC) has been applied in the low-temperature heat pump system with the purpose of achieving higher system efficiency. However, the traditional SSC with even-grooves screw rotor behaves high torque fluctuation to the motor, thanks to its work synchronously and doubled compressed gas-induced torque on the screw rotor axis. It is more serious in the low-temperature heat pump system because of the higher pressure ratio. In this paper, an odd-grooves screw rotor design is proposed to smooth the compressed gas-induced torque on the screw rotor axis, by arranging the two compression chambers work alternatively. A dynamic model for the screw rotor is established to calculate the gas force and the gas-induced torque on screw rotors under different working conditions. The results show that the odd-grooves screw rotor design can remarkably reduce the gas-induced torque fluctuation of the SSC. Meanwhile, the maximal load on the bearing caused by the odd grooves design could be controlled below the maximum allowable load of the bearing.