Energy conversion efficiency and performance prediction of multistage multiphase pumps: mechanistic modeling and experimental validation

Compared with conventional separated transportation technology, multistage multiphase pumps achieve remarkable reductions in energy consumption and carbon emissions of fluid transportation systems, facilitating the achievement of Sustainable Development Goal 7 (SDG 7). However, under near-critical gas volume fraction (GVF) conditions, intense interphase interactions and topological evolution of flow patterns within the flow field induce severe irreversible dissipation, resulting in an abrupt drop in energy conversion efficiency. Most existing models simplify three-dimensional interphase interactions to one-dimensional empirical corrections and generally ignore the interstage GVF attenuation effect caused by gas compressibility. These limitations prevent accurate reflection of the nonlinear pressurization drop and severely hinder the precise evaluation of system energy efficiency. Therefore, a mechanistic model for energy conversion and performance prediction of multistage multiphase pumps is established in this study. Under single-phase flow, the model quantifies frictional and shock losses as basic dissipations; under two-phase flow, it incorporates interphase slip loss and flow‑pattern transition loss, revealing their distinct dissipation mechanisms. For multistage coupling, an interstage dissipation recursive framework with the evolution of local GVF as the independent variable is constructed. Experimental validation shows that the prediction errors are within ±10% and ±20% under single‑phase and two‑phase conditions, respectively. This model successfully reproduces the near‑critical abrupt head drop behavior that conventional models fail to capture, and reveals the spatial heterogeneity of internal dissipation in multistage pumps. Furthermore, the model exhibits excellent generalization capability across pump types, providing reliable theoretical support for low‑energy design and energy‑efficient operation of multiphase fluid transportation systems.