Modeling and simulation of supercritical CO2 flow in a heavy-duty centrifugal compressor: A design robustness assessment in the liquid-like region

Abstract

This study models and simulates supercritical CO2 behavior on the fourth stage of an industrial-scale centrifugal compressor, operating near the critical point in the liquid-like region. Computational fluid dynamics (CFD) simulations assessed steady-state, three-dimensional turbulent flow with a domain comprising the inlet duct, impeller, and vaneless diffuser. The novelty of this work lies in evaluating the robustness of the rotor design under realistic operational conditions found in floating production storage and offloading (FPSO) units, through the application of a metastable thermodynamic model to capture property variations in the liquid-like region. A phase change and cavitation hypothesis are addressed. Entropy analysis showed most losses in the middle rotor passage. Key metrics like pressure ratio, isentropic efficiency, and input power were analyzed to enhance understanding of CO2 behavior.