What is meant by compound compression in a refrigeration system?

Compound compression in a refrigeration system refers to having two compression stages within one compressor unit. This design is utilized to increase the efficiency and effectiveness of the refrigeration cycle by allowing the refrigerant to be compressed in two steps rather than a single stage.

By dividing the compression process into two stages, the system can operate at higher pressures while maintaining lower temperatures at each stage, resulting in improved performance and more effective heat transfer. The first stage of compression typically raises the refrigerant from a lower pressure to an intermediate pressure, and the second stage then raises it from the intermediate pressure to the desired discharge pressure.

This method can lead to better energy efficiency, as well as lower discharge temperatures, which can help to extend the life of the compressor. In other configurations like those where multiple compressors work in parallel or where single-stage compression occurs, the benefits of two-stage compression may not be fully realized, as those setups do not leverage the advantages of incremental pressure increases in a single unit.