Performance Analysis of Oil Injected Twin Screw Compressor

Abstract

Oil injected twin-screw air compressors are widely used for medium pressure applications in cryogenic industries. Conversion of these compressors for helium applications is in great demand due to their inherent advantages. A mathematical model of an oil injected twin-screw compressor has been constructed basing on the laws of perfect gas and standard thermodynamic relations to evaluate compressor efficiencies. The complete model has been validated using experimental data. Flow and heat transfer coefficients required for computer simulation are experimentally obtained and used in performance prediction, the working medium being air or helium. For example, the heat transfer coefficient is determined from experimentally obtained volumetric efficiencies at varying inlet gas temperatures. Influence of injected oil temperature and quantity, pressure ratio and rotational speeds on volumetric and adiabatic efficiency for sample rotors is analyzed. Conversion of oil injected twin-screw air compressor for helium compression is aimed at, based on numerical and experimental results.