A design method of impeller inlet of supercritical carbon dioxide centrifugal compressor

Abstract

The invention discloses a design method for an impeller inlet of a supercritical carbon dioxide centrifugal compressor, and aims to provide a design method capable of restricting the condensation phenomenon at the impeller inlet, maintaining geometric compactness and high thermal cycle efficiency. It includes the following steps: the total temperature at the inlet of the impeller, the total pressure at the inlet of the impeller, the target flow function, the Mach number of the machine and the inlet angle of the pre-rotation are given; the total enthalpy of the inlet of the impeller is calculated; Accept the acceleration margin empirical coefficient and steam fraction value; calculate the maximum expansion Mach number, determine the acceptable expansion Mach number according to the obtained maximum expansion Mach number; determine the impeller inlet absolute Mach number according to the obtained acceptable expansion Mach number; according to the obtained impeller inlet absolute Mach number Calculate the static parameters of the impeller inlet under actual conditions; calculate the average isentropy index, calculate the relative axial airflow angle of the optimal impeller inlet cover, calculate the relative Mach number of the impeller inlet cover, and calculate the impeller inlet shape coefficient.

Description

technical field [0001] The invention relates to the technical field of centrifugal compressor design, in particular to a design method for 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, and smaller viscosity. Compared with superheated steam, with SCO 2 The energy system as a fluid working medium usually requires less compression work and has a higher cycle efficiency. In addition, SCO 2 is very dense, therefore, compared to the traditional Rankine cycle, the SCO 2 The Brayton cycle has a more compact structure. Furthermore, CO 2 The critical temperature (304.13K) of SCO is much lower than other commonly used working fluids, which makes SCO 2 The Brayton thermodynamic cycle is easier to implement. Due to the above advantages, SCO 2 The Brayton cycle is widely use...

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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