Simulation of dry screw vacuum pumps based on chamber model and thermal resistance network

Abstract

Current simulation for dry screw vacuum pumps fails to reflect the influence of heat transfer and component thermal deformation due to the lack of an effective simulation path. This paper proposes a novel simulation method based on the chamber model and thermal resistance network method, which integrally considers the influence of leakage, heat exchange as well as components’ temperature and deformation. First, the working process of dry screw vacuum pumps was analyzed and simplified to introduce the chamber model and thermal resistance network method. In detail, the chamber model was employed to predict the gas pressure and temperature in working chambers, and the thermal resistance network was introduced to simulate the component temperature by assuming rotors and casing only performing axial temperature distribution. Next, the detailed construction processes of the chamber model and thermal resistance network were presented. A simulation procedure was developed based on the iterative solution of the chamber model and thermal resistance network. Further, a specific case with detailed simulation setup, solution process, and experimental verification was given for a test dry screw vacuum pump. The results showed that the proposed simulation method performed a better agreement with the experimental pumping speed curve than the previous isothermal model and could effectively predict the component temperature under different inlet pressures and rotation speeds. Finally, the simulated results were further discussed to reveal the gas temperature, component deformation, and leakage process in dry screw vacuum pumps. The conclusions obtained could effectively guide the design and development of dry screw vacuum pumps.