Historically, the move toward multistage compression systems in industrial refrigeration applications was rooted in demand for lower operating temperatures. First generation compression technologies consisted of reciprocating compressors, but later rotary vane machines also were used. These two machines faced some key constraints in their operation at low temperatures. Reciprocating and rotary vane compressors have physical compression ratio (ratio of absolute discharge to absolute suction pressure) limits that are quickly approached as operating temperatures decrease. Additionally, compressors and the oil used in the compressors have limits on discharge gas temperature.
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