Characterization of a vapor injection scroll compressor as a function of low, intermediate and high pressures and temperature conditions

• Characterization and analysis of the performance of a vapor injection compressor.
• Comparison of a vapor injection compressor with a single stage compressor.
• Evaluation of the influence of the intermediate conditions on the compressor performance.
• Relation between the injected mass flow and the intermediate pressure.
• Advantages and limitations of vapor injection scroll compressor design.

The interest in two stage cycles has increased in the last years and some compressor manufacturers have commercialized compressors adapted to work in these conditions. Nevertheless, the information supplied by them usually is limited to certain design conditions defined by the application and extrapolation to other conditions is not straightforward. In this article a test campaign of an injection scroll compressor is presented. This test campaign was divided in two parts, on the first one a wide range of evaporating and condensing pressures for the intermediate conditions recommended by the manufacturer were measured, and the compressor behavior was systematically compared with single stage compressor of the same volume. On the second part an experimental study of the influence of the intermediate conditions on the performance have been done. The study has included the evaluation of the separate influence of intermediate gas superheat, intermediate pressure and wet injection.