A Novel Method for Rotor Profile Optimization of High Temperature Screw Expanders Employed in Waste Heat Recovery Systems

High temperature expanders have always been employed in industrial waste heat recovery systems, where twin‐screw expanders were frequently adopted. However, the significant thermal deformation of rotors contributes to much technical difficulty on the designation and manufacturing of high temperature twin‐screw expanders. The profile should be optimized with consideration of its thermal deformation in high temperature working conditions. In this article, a novel method for twin‐screw expander profile optimization is developed. The thermal deformation of rotors is considered with meshing pair rules and interlobe clearance presetting. Theoretical analysis on interlobe clearance is made any steam inlet temperature from 20°C to 400°C, while experimental facility was built to figure out its reliability at high temperature. The optimized profile proved the effectiveness of this method. The clearance decreases significantly, decreasing from 1.28 mm at the working temperature of 20°C to 0.16 mm at 400°C. The testing results illustrated that the significant thermal deformation of rotors causes much interlobe abrasion once the operating temperature reached 400°C. With clearance of 0.1 mm and the radius correction angle of 0.0758°, the screw expander was proved to be reliably working at 400°C.