This paper summarizes three Quimby-tooth rotor profile (QRP) generation models for dry screw vacuum pumps. Seven typical profiles are generated and compared to reveal their differences in curve structure, meshing line, parameter design range, and geometrical characteristics. The analysis indicates that there still is insufficient design flexibility for the typical profiles in the application of conical rotors. Therefore, a novel rotor profile is further proposed, in this paper, by modifying an existing profile. The advantage of the novel profile is identified through a specific design case. Results show that the summarized profile generation models provide an effective means to generate typical profiles and create novel profiles. In comparison with traditional profiles, the proposed profile achieves a 2.8% reduction of the contact line length and a 1% boost of the internal compression degree for conical rotors. This paper presents effective references for profile design and optimization of dry screw vacuum pumps. Graphic Abstract [ ]

The large-scale utilization of hydrogen energy is currently hindered by challenges in low-cost production, storage, and transportation. This study focused on investigating the impact of the diaphragm cavity profile on the movement behavior and stress distribution of a dual-stage diaphragm compressor. Firstly, an experimental platform was established to test the gas mass flowrate and fluid pressures under various preset conditions. Secondly, a simulation path integrating the finite element method simulation, theoretical stress model, and movement model was developed and experimentally validated to analyze the diaphragm stress distribution and deformation characteristics. Finally, comparative optimization analyses were conducted on different types of diaphragm cavity profiles. The results indicated that the driving pressure differences at the top dead center position reached 85.58 kPa for the first-stage diaphragm and 75.49 kPa for the second-stage diaphragm. Under experimental conditions of 1.6 MPa suction pressure, 8 MPa second-stage discharge pressure, and 200 rpm rotational speed, the first-stage and second-stage diaphragms reached the maximum center deflections of 4.14 mm and 2.53 mm, respectively, at the bottom dead center position. Moreover, the cavity profile optimization analysis indicated that the double-arc profile (DAP) achieved better cavity volume and diaphragm stress characteristics. The first-stage diaphragm within the optimized DAP-type cavity exhibited 173.95 MPa maximum principal stress with a swept volume of 0.001129 m³, whereas the second-stage optimized configuration reached 172.57 MPa stress with a swept volume of 0.0003835 m³. This research offers valuable insights for enhancing the reliability and performance of diaphragm compressors.