Two-stage compression is defined as which of the following?

Two-stage compression is a process in which gas is compressed in two distinct stages, typically involving two separate compressors, where the output of the first stage is then fed into the second stage for further compression. This method improves the efficiency of the compression process and reduces the potential for overheating of the gas.

In this scenario, the correct answer accurately describes that in two-stage compression, the compressors work in series. The first compressor raises the pressure of the gas to an intermediate level, and then the gas is routed to the second compressor, which further raises the pressure to the desired level. This multi-step approach enhances overall performance, allowing for better management of thermal energy and efficiency during the compression process.

The other options do not accurately represent the concept of two-stage compression. For example, running two compressors in parallel or having them discharging into a condenser or intercooler does not involve sequential compression stages, which is essential for defining two-stage compression.