Experiment and Multiphysics Simulation of Inductively Heated Concrete Thermal Energy Storage Systems

Abstract

This study presents an experimental and multiphysics modelling investigation of inductively heated concrete thermal energy storage (CTES) systems incorporating different heat transfer fluid (HTF) passages. Three HTF designs, including single-tube (ST), multiple-tube (MT), and triply periodic minimal surface (TPMS)-based heat exchanger structures, were experimentally evaluated under different induction heating conditions. Thermal charging to 260 °C was achieved using a 55 V, 50 kHz high-frequency induction heating system that takes advantage of the metallic structures embedded in the CTES, while discharging was realised via forced-convection airflow. Temperature evolution and pressure drop were measured to evaluate the thermal–hydraulic behaviour of the CTES modules. Furthermore, a coupled multiphysics numerical model integrating electromagnetic induction, heat transfer, and fluid flow was developed and validated against these experimental results. A ±5% coil-current sensitivity analysis across ST, MT, and TPMS identified 110 A and 130 A as the most representative currents for the 200 mm and 150 mm coils tested. Advanced metallic heat exchanger geometries significantly improved inductive charging over the conventional ST configuration. For the 200 mm coil, MT and TPMS advanced configurations increased maximum charging power by about 94% and 82%. The 150 mm coil further boosted charging, with TPMS showing the best performance. The parametric modelling shows that improved induction coupling and larger heat-transfer surfaces with helical fins helped achieve comparable charging/discharging power and energy storage. The induction-assisted CTES system shows strong potential for flexible thermal energy storage and offers new insights into integrating HTF metallic structures with induction heating.