screw machine, screw motor, screw engine, waste heat recovery, thermodynamic design
This paper focuses on the interaction of the geometric parameters of screw motors and the fluid parameters of the system in compliance with the boundary condition of constant waste heat flow. Within the thermodynamic simulation the systematic variation of the geometric machine parameters include the number of lobes on male and female rotor and the internal volume ratio. The variation range of the system parameters consists of the dependent parameters of temperature and mass flow and of the pressure on the high pressure side of the machine. The conclusive assessment of the energetic efficiency and the operating behavior of the screw motor are demonstrated by the use of the internal power, the delivery rate and classification numbers for the inlet area and the gaps. The computed operational parameters and geometries of screw engines in applications of waste heat recovery differ significantly from the previously used machines.