Improvement and design of ejectors for steam turbines and chillers

The correlation between the geometrical parameters, performance characteristics and purpose (for condensation or cogeneration turbines) of multistage steam-driven ejectors has been identified and summarized. The analysis was based on a study of 24 serial ejectors analyzing the position of the “effective cross section” (in which the entrained mixture reaches or passes the speed of sound), the ejector’s general geometric parameter (the ratio of the areas of critical sections of the mixing chamber and the nozzle), various values of the axial position of the nozzle, the distribution of compression ratios in multistage ejectors and changes in the critical diameters of nozzles in the ejector’s stages. • A specific methodology for the design and calibration of calculations for multistage steam-driven ejectors was developed based on the analysis and synthesis of the results of industrial tests, a summary of the geometric characteristics of serial ejectors and numerical simulation. The methodology for the design and calculation was refined in order to reduce the consumption of working steam, to determine the position of the “effective cross section”, to choose the main geometrical parameter of the ejector and to distribute the degrees of compression over the ejector’s stages. The developed methodology for the calibration calculation allows one to determine the characteristics of the ejector stages with the given geometric dimensions of jet devices and the flow shares of the steam condensing in the intermediate coolers. • A gas-dynamic effect of a significant change in the pressure of the steam-air mixture in the ejector’s intercoolers was detected. Compared with the inlet pressure, the pressure of the steam-air mixture at the outlet from the coolers decreases by ΔР = 1.0 ... 4.0 kPa or increases by ΔР = 1.0 ... 8.6 kPa. A physico-mathematical model has been developed that describes the effect of pressure increase as a pressure leap in a two-phase, two-component medium formed at the inlet to the heat exchanger. All major scientific results have been confirmed experimentally.