Design method of impeller inlet of supercritical carbon dioxide centrifugal compressor

Abstract

The invention discloses a design method of an impeller inlet of a supercritical carbon dioxide centrifugal compressor, and aims to provide a design method capable of limiting the condensation phenomenon of an impeller inlet, keeping geometric compactness and achieving high thermodynamic cycle efficiency. The method comprises the following steps: giving an impeller inlet total temperature, an impeller inlet total pressure, a target flow function, a machine Mach number and a prewhirl air inlet angle; calculating an impeller inlet total enthalpy; determining an impeller inlet total entropy, an impeller inlet static entropy, an acceptable acceleration margin empirical coefficient and a steam score value; calculating a maximum expansion Mach number, and determining an acceptable expansion Machnumber according to the obtained maximum expansion Mach number; determining an impeller inlet absolute Mach number according to the obtained acceptable expansion Mach number; calculating an impeller inlet static parameter under the actual condition according to the obtained impeller inlet absolute Mach number; and calculating an average isentropic index, calculating an optimal impeller inlet wheelcover relative axial airflow angle, calculating an impeller inlet wheel cover relative Mach number, and calculating an impeller inlet shape coefficient.

Description

technical field [0001] The invention relates to the technical field of centrifugal compressor design, and more specifically relates to a method for designing an impeller inlet of a supercritical carbon dioxide centrifugal compressor. Background technique [0002] supercritical carbon dioxide (SCO) 2 ) has excellent thermodynamic properties, such as larger specific heat capacity and isothermal compressibility coefficient, and smaller viscosity. Compared with superheated steam, SCO 2 Energy systems as fluid working fluids generally require less compression work and have higher cycle efficiency. In addition, SCO 2 The density is very large, therefore, compared with the traditional Rankine cycle, the SCO 2 The Brayton cycle has a more compact structure. Furthermore, CO 2 The critical temperature (304.13K) is much lower than other commonly used fluid working fluids, which makes SCO 2 The Brayton thermodynamic cycle is easier to implement. Due to the above advantages, SCO ...

AI Technical Summary

Problems solved by technology

This means that for a given mass flow, the cross-sectional area of ​​the impeller inlet becomes relatively large, making the compressor less compact

So far, the existing design methods can not solve the above contradictions well

It is necessary to develop a new impeller inlet design method to achieve the comprehensive effect of limiting the condensation phenomenon at the impeller inlet and ensuring the compactness of the compressor without losing cycle efficiency

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