DEVELOPMENT OF A TWIN SCREW CO_2 COMPRESSOR AND ITS APPLICATION IN NH_3/CO_2 CASCADE REFRIGERATION SYSTEM

摘要

The CO_2 compressor is one of the key parts in an NH_3/CO_2 cascade refrigeration system. In order to improve its efficiency, a twin screw compressor was developed using in CO_2 subcritical condition. The design and the product research of the compressor were conducted aimed at practical application. The design included rotor profile, the volume variation and the discharge port. The compressor assembly clearance was calculated based on the compressor force analysis and numerical simulation of the compressor working conditions. The volumetric and adiabatic efficiency of the compressor in several operating parameters was investigated. And the cascade system COP changing with the CO_2 evaporating temperature was also studied based on the experimental data. Some conclusions on the design of twin screw CO_2 compressor and NH_3/CO_2 cascade system are obtained.