Transport phenomena during solidification and melting of water: Experimental and numerical studies

Abstract

Understanding water solidification and melting is crucial for optimizing water-based thermal energy storage systems and designing containers that accommodate ice expansion without structural damage. This study uses experiments and numerical simulations to investigate the shape of the solid-liquid interface, thermal history, velocity distribution, and solid fraction of water during successive solidification and melting processes. PIV (Particle image velocimetry), shadowgraph, and DSLR imaging are used to capture the flow pattern and solid-liquid interface during the phase change process. Eight thermocouples were placed inside the cuboidal cell to collect temperature data, which was subsequently compared with results from Fluent simulations.

Based on thermal data, the solidification process is divided into three distinct regimes: convective dominant, constant temperature, and solidifying. Flow behaviors are analyzed using the simulation velocity field, experimental velocity field, and thermal Rayleigh number. The simulation reported the maximum height of ice during expansion for different aspect ratios. The melting process revealed complex convective flow patterns, including side convection, Rayleigh-Bénard convection near the bottom region, air convection in the upper sections, and ice toppling, causing temperature fluctuations in a zig-zag pattern through experiments. Numerical simulations showed similar trends to experimental results but differed in specific temperature values and behaviors, particularly during melting. The simulation indicated that melting occurs through convective flows, while experimental observations highlighted additional factors such as mixing, melting water, ice movement, and varying convective patterns. This research provides a comprehensive understanding of water's solidification and melting behavior using experiments and numerical simulations, which shows the role of convection.