Piston Compressor Behaviour

These differ in their characteristics decisively from flow equipment which include the turbo compressors that are common in very large systems. In Piston Compressors the flow rate is mainly dependent on the displaced volume and speed. Smaller refrigeration systems usually have a Piston Compressor. Because the flow rate is a measure for the refrigeration capacity of the refrigeration system, the properties of the compressor are important for the capacity of the whole system. Piston compressors are positive displacement machines. Due to the unavoidable dead space the flow rate drops with increasing pressure ratio. 

Experimental unit for piston compressor from refrigeration
Open process with air
Inlet pressure and outlet pressure (pressure ratio) adjustable via valves
Instruments: 2 manometers, flow meter, sensors for pressure, temperature, speed, torque (via force), flow rate, digital power indication
Typical open 2-cylinder compressor
Drive via asynchronous motor with frequency converter for speed adjustment.