Abstract:

Phase change thermal energy storage (PCTES) leverages the absorption/release of substantial latent heat during material phase transitions to store/release energy, offering advantages such as high energy density, minimal temperature fluctuations, and compact volume. This study integrates topology optimization with PCTES, focusing on shell-and-tube phase change units. A mathematical model for optimization was established through dimensionless governing equations, examining the effects of thermal diffusivity ratio, Stefan number, and natural convection on fin structure evolution. Geometric reconstruction was applied to topology-optimized results, followed by numerical simulations and comparative analyses against conventional straight-fin structures and non-reconstructed optimized designs. Key findings include: (1) Natural convection significantly impacts topology-optimized configurations, with distinct structural differences observed between conduction design and convection design; (2) Reducing the thermal diffusivity ratio or increasing the Stefan number promotes radial growth of fin structures; (3) Simulations of five fin configurations reveal that topology-optimized designs substantially enhance heat transfer efficiency. The convection design reduced the time for the model to reach an average dimensionless temperature of 0.9 by 30.1% and shortened the complete phase transition duration by 50.8%. Furthermore, conduction and convection designs exhibit respective advantages under different application scenarios and storage objectives, necessitating scenario-specific selection. This work provides valuable insights for optimizing phase change thermal energy storage devices.

Key words: phase change thermal energy storage, topology optimization, heat transfer enhancement, numerical simulation, fin structure