Toward High Thermal-Hydraulic Performance of Heat Exchangers for Water-Gravel Thermal Energy Storage

Water-gravel thermal energy storage (WGTES) offers a cost-effective and environmentally sustainable solution for large-scale seasonal thermal energy storage, with performance strongly dependent on the layout and operation
of charging and discharging heat exchangers. This study presents a simulation-driven methodology for optimizing heat exchanger design in a WGTES with three neighboring storage units at the incampus demo site of the
INTERSTORES project.
A detailed COMSOL Multiphysics® model is developed to capture both thermal and hydraulic interactions between the heat exchangers and the porous gravel matrix. Parametric analyses investigate different heat exchanger configurations. Performance is assessed via a thermal-to-hydraulic ratio. Results show that layout, multi-level configurations and operating conditions significantly affect thermal performance, hydraulic losses and overall efficiency.
This work demonstrates the value of multiphysics modeling for performance-optimized WGTES design and provides a transferable framework for large-scale seasonal storage planning.