A real gas-based throughflow method for the analysis of SCO₂ centrifugal compressors

Abstract

The supercritical carbon dioxide Brayton cycle is recognized as a promising candidate for the next generation of nuclear power and energy system. Among all the components in the cycle, the centrifugal compressor is one of the most important ones. This paper presents a streamline curvature throughflow method based on real gas properties and capable of dealing with condensation flows in the supercritical carbon dioxide compressors. A fluid thermodynamic property calculation method based on look-up tables is adopted to account for the real gas effects and fluid condensation and to reduce the computational time. For extending the simulation capability to the region below the saturation curve to assess the condensation possibility, the homogeneous equilibrium model is adopted. Finally, the real gas-based streamline curvature method is applied in the analysis of a supercritical carbon dioxide centrifugal compressor working near the critical point. Then, computational fluid dynamics calculations are performed to validate the method in detail. The results of the computational validation indicate that the real gas-based streamline curvature method presented in the paper can obtain an accurate enough flow field as that obtained by three-dimensional computational fluid dynamics simulations considering the coarse grid and the much less calculation time.

Unsteady two-phase region evolution of SCO2 centrifugal compressor

“…Given the strong nonlinear features of CO 2 near the critical point, the NUMECA FINE was coupled with the real CO 2 fluid in NIST REFPROP in the numerical calculations to perform the simulation of the flow in the compressor. The homogeneous equilibrium model (HEM) 32,33 was employed to treat the possible two-phase flow in the centrifugal compressor. Considering that gas and liquid have similar density magnitudes near the critical point, the HEM assumes that vapor and droplets have the same temperature, velocity, and pressure in the two-phase region, 34,35 which is considered to be reasonable.…”

Effects of Near-Critical Condensation and Cavitation on the Performance of S-CO2 Compressor

“…Condensation occurs in the gas environment, and cavitation occurs in the liquid environment. Condensation droplets on the impeller blade may further deteriorate the performance of the compressor or cause erosion [11][12][13][14]. Cavitation can generate large amounts of bubbles, and bubbles occupy most of the channel, resulting in blockage [15][16][17].…”

Time-Marching Throughflow Analysis of Centrifugal Compressors with Boundary Conditions Based on Newton’s Method

“…Among them, the throughflow method has become the backbone of turbomachinery design. Benefitting from its good balance between computation efficiency and accuracy, the throughflow method has been commonly adopted in the preliminary design and optimization stage both for axial [1][2][3][4][5][6] and radial turbomachinery [7][8][9][10]. As has been reported, up to 80% or more of the design parameters may be fixed during the throughflow modeling phase [11].…”