Experimental data analysis and dimensionless exergy levels in a commercial stratified thermal storage

The continuously rising demand for renewable energy sources within the energy system has highlighted the need for technologies capable of mitigating the impact of renewable energy intermittency and addressing the generation-demand mismatch in the system. Thermal energy storage (TES) emerges as a versatile storage medium with a wide range of applications, spanning from solar energy utilization and power peak shaving to the storage of industrial waste heat. In this study, data collected from an operating commercial stratified tank are used to validate a 2-D axisymmetric CFD model. Temperature profiles are collected throughout one month with a one-minute refresh rate. The model replicating the tank is generated in COMSOL Multiphysics® and validated by emulating the registered charging phases of the real storage. The model is then employed to optimize the stratification capability of the tank, by varying the logics applied to pinpoint optimal values of both inlet water temperature and velocity. The study aims to maximize the exergetic efficiency of the system using dimensionless exergy, a parameter often utilized in literature to identify the ability of the storage to generate and preserve optimal temperature stratification. Finally, the experimental dimensionless exergy has been evaluated for the aforementioned temperature profiles.