Grey-box modelling of melting inside a rectangular enclosure for predictive control strategies of latent thermal energy storages

An optimized operation of latent thermal energy storage requires the implementation of smart control strategies, which are based on simplified models that can predict the behavior of the system under diverse operating conditions. Numerical simulations are too computationally expensive to be used in real-time control. The present study proposes a grey-box modelling approach for melting inside a rectangular enclosure with an isothermal side wall. Parametric numerical simulations are performed that consider a range of wall temperature values to generate a reference dataset. The grey-box model uses interpolation on the reference dataset for the non-dimensional groups that describe the problem. The performance of the model is assessed for a case with a transient wall temperature profile and the results of the grey-box model closely match the simulation results. The proposed grey-box modelling approach captures the main dynamics of the solid-liquid phase change process including latent and sensible heat effects.