Numerical Analysis of Performance, Rotor Temperature Distributions, and Rotor Thermal Deformation of an R134a Screw Compressor

摘要

A numerical analysis is performed to systematically calculate the performance, rotor temperature distributions, andrnrotor thermal deformation of an R134a screw compressor. The analysis procedure includes three major steps. Thernfirst step calculates the efficiencies and the temperature- and pressure-time histories of the refrigerant during arncompression cycle of the screw compressor. The calculation is performed based on a theoretical model, whichrnconsiders the mass and energy conservation laws, the leakages through various paths, and the discharges of gas andrnoil. The heat transfer between gas and oil is also considered. The second step calculates the temperature distributionsrnin the rotors by numerically solving the set of Helmholtz equations derived from the partial differential equations forrntransient heat conduction of the rotors. Each of the two rotors is subject to a periodic convective boundary conditionrnand five steady boundary conditions. The third step calculates thermal deformations of rotors by a finite elementrnmethod based on the calculated temperature distributions from the second step. The proposed theoretical models andrnnumerical procedures are shown to be able to efficiently calculate the performance, rotor temperature distributions,rnand rotor thermal deformations. The calculated information is important and useful in the design of a refrigerantrnscrew compressor.