Optimizing structured thermocline performance using a 3D+1D advanced model

Abstract

This paper presents an advanced numerical simulation of structured thermocline thermal energy storage systems integrated with concentrated solar power plants. The system consists of a single-tank configuration with a packed bed of ceramic filler materials with channels for molten salt circulation, aimed at reducing costs and improving thermal performance. A detailed mathematical model solves the unsteady 3D heat equation in the solid domain, coupled with 1D models for the heat transfer fluid flow. After conducting a detailed numerical study to ensure both time-step and grid independence results, a reference case was simulated along with a parametric study to evaluate the effects of geometric configurations, operational conditions, and cycle durations on system performance. The parametric study highlights the influence of the mass flow rate on the charging and discharging power. The novelty of this work lies in the coupled 1D-3D modelling framework, which captures transient thermal gradients within structured ceramic solids, an aspect often neglected in traditional 1D approaches. This allows for more accurate thermal performance predictions, aiding the design and optimization of future TES systems. The findings offer valuable insights for improving the efficiency and cost effectiveness of renewable energy storage, particularly in CSP and decentralized energy applications.