Optimizing flow characteristics of phase change ice slurry cold storage system driven by multi-scale flow mechanisms

As an efficient phase change cold storage medium, the flow characteristics of ice slurry during its transportation process have a crucial impact on the energy efficiency and stability of the system. This study, utilizing a computational fluid dynamics (CFD) - Population Balance Model (PBM) coupled model, investigates the flow behavior of ice slurry in a perturbed pipeline. It focuses on the evolution of ice crystal particle size, phase distribution patterns, and flow parameter characteristics. The Euler-Euler two-phase flow model is adopted to describe the liquid-solid interaction. Combined with the RNG k-ε turbulence model and the PBM, ice crystal nucleation, aggregation, and breakage kinetic processes are quantified. The model reliability is ensured through grid independence verification and comparison with experimental data. The research results show that the ice volume fraction exhibits an asymmetric distribution along the longitudinal axis of the pipeline. A high-concentration aggregation region forms near the upper wall surface due to buoyancy effects. In contrast, the lower wall surface has a low concentration due to the deposition of the carrier phase. The velocity distribution exhibits axial symmetry. The initial flow velocity significantly affects the pressure drop. When the flow velocity increases from 1 m/s to 3 m/s, the pressure difference increases by more than 1000 Pa. The perturbed baffle enhances the mixing by inducing eddies, but intensifies the local resistance fluctuations. This study reveals the multi-scale flow mechanism of ice slurry in complex pipelines, providing a theoretical basis for optimizing the transportation efficiency of the cold storage system and suppressing the ice blockage phenomenon.