Modellazione dei sistemi di accumulo termico per impianti solari

The study regards Thermal Energy Storage Methods (focusing on Sensible Heat Storage) and simulating models. A solar assisted domestic heating plant with collectors, storage, loads, thermal losses and eventual heat exchanger is simulated. In order to evaluate the storage behaviour two simulations models are realized: a fully mixed model and a stratified model, with multinode approach. The uniform temperature model includes two options for collectors energy input (constant or with linear variation) and load (with constant or variable on –off profiles). Both simulation models use Runge-Kutta method, with Ode 45 Matlab Function. Model validation has been determined by comparing the results of simulations with available data from literature obtained with different methods (Euler, Heun) and/or analytical results. Simulation tests under different conditions are made (different load profiles and flow rates) in both models, and the results are compared between two models and with available literature results As expected, results show a relationship between flow rate increasing and stratification reduction. Furthermore, peak temperatures appearing in stratified model contribute to increasing efficiency of the system