Thermodynamics Analysis of Roots Vacuum Pump

Abstract

Abstract As a kind of fluid machinery, the roots vacuum pump is widely used in the metallurgical industry and semiconductor industry. The double-blade roots vacuum pump is widely used in the vacuum system due to its easy manufacture and low cost. The pumping process can be divided into four distinctive processes (i.e. sucking process, transferring process, backlashing process and exhausting process). The characteristics of each process are illustrated sufficiently in this paper. Based on the ideal gas laws, a thermodynamics model of pumping process is established and the influence of gas leakage on the pumping process is taken into consideration. Using this model, quantificational expressions of five gas thermodynamic parameters (volume, mass, pressure, temperature and internal energy) are given. The performance curves are plotted by MATLAB and the pumping characteristics of double-blade roots vacuum pump are discussed at last. This research can provide a theoretical reference on the design of double-blade roots vacuum pump.