Energy potential of dual lead rotors for twin screw compressors

The paper deals with a theoretical investigation into the ways in which fluid properties influence the optimal geometrical parameters of dry running twin screw compressors with uniform and dual lead rotors. Dual lead rotors possess two segments with different rotor leads in order to optimise the progression of chamber volume, clearance size and outlet area. Optimal geometry parameters are determined by means of a multi-chamber model simulation. Fluids are treated as an ideal gas and fluid properties are varied systematically in order to provide guidance on how the machine should be designed for a particular application. The optimal geometry parameters mainly depend on the speed of sound and isentropic exponent of the fluid, because they influence outlet throttling during discharge, and pressure progression due to volumetric compression. In particular, the values for the rotor wrap angle and the internal volume ratio need to be adjusted individually for each compressor application. The results reveal that dual lead compressors possess most potential for fluids with low speed of sound and isentropic exponent.