Numerical investigation of dynamic flow and melting behavior of high-concentration ice slurry for sustainable pipeline cleaning

• Novel mixture model presented with phase change and dynamic wall temperature. • Effective cleaning distance of thick ice slurry in a horizontal pipeline achieved. • Edge-to-center melting with axial and radial ice fraction variations discussed. • Finger-shaped slurry–water interfaces is driven by viscosity differences. • Guidelines given for energy-efficient design of ice slurry pipeline cleaning. High-concentration ice slurry is a promising and environmentally friendly solution for energy-efficient pipeline cleaning due to its high latent heat and effective scouring ability. A novel mixture model based on the kinetic theory of granular flow incorporating a phase-change melting model and a dynamic wall temperature function has been developed to simulate the dynamic flow and melting behavior of thick ice slurry in a horizontal pipe. Numerical simulations are compared to experimental data, and results primarily focus on the ice slurry flowing distance before complete melting, effective flowing distance, melting characteristics, formation and evolution of the slurry-water interface, as well as the temperature distribution across different regions of the pipe. Results confirm that injection length, concentration, and velocity of the slurry have a significant effect on its flowing distance, and that the ice slurry melting rate gradually decreases. In addition, the ice slurry exhibits a distinct edge-to-center melting pattern, with the outer layers melting first and surrounding the central region. The ice volume fraction decreases from the center toward both ends from the axial direction, and the ice volume fraction is lowest at the bottom and gradually increases with height. The front and rear interfaces between the ice slurry and water appear finger-shaped, however behaving differently due to the viscosity difference. Numerical results are shown to match well the experimental data, providing a useful numerical tool and guidance for the design and operation of ice slurry-based pipeline cleaning systems.