Based on the principle of gas compression

For a dynamic compressor, a continuous totfUtng element (rotor) js used to increase gas velocity. Then, gas velocity is converted to static pressure at compressor outlet. Dynamic compressor is classified as centrifugal or axial compressor. For centrifugal compressor, the rotating element is an impeller, and gas flow is in either radial or mixed flow direction. For axial compressor, the rotating element is a bladed rotor and gas flow is in the axial directioa 

Positive displacement compressor uses mechanical components to trap gas and then compress it to hi er pressure. Positive displacement compressor can be further classified into reciprocating compressor and rotary compressor. Reciprocating compressor uses reciprocating motion of piston, plunger, or diaphragm in a cylinder or head to compress gas. Rotary compressor uses continuous rotating screws, lobes, vanes, or liquid ring to compress gas. 

Thermal type compressor Is ejector, which uses high velocity motive fluid (such as gas or steam) to entrain the process gas. Then, it converts the velocity of the mixture to pressure in a diffuser. 

Compressors Screw, Lobe, Sliding Vane, Liquid-Ring 

---