Object-oriented modeling and performance evaluation of a PCM-based ventilation system

The buildings sector is a large energy consumer, so improving the building block energy performance through implementing energy-efficient techniques would aid in attaining the energy and environmental goals. Among energy-saving technologies, Latent Thermal Energy Storage (LTES) systems have drawn great attention to be applied in buildings as they enable more efficient and cost-effective thermal management by reducing energy use or shifting peak loads. Particularly, Phase Change Material (PCM), as a storage medium in LTES systems, has received considerable attention in recent research studies and investigations. This study aims at modelling and assessment of a PCM-driven ventilation system. An energy storage system with four PCM stacks was modelled using Modelica language considering the physical and operational parameters. Subsequently, the influence of parameters on PCM temperature was evaluated by sensitivity analysis. Using collected data from a system experiment, unknown parameters for the first stack were estimated on the first 3 days and validated on the following 2 days through minimizing Root Mean Square Error (RMSE) of predicted PCM temperature to the measured temperature using a genetic algorithm. The estimated parameters were applied to the four stacks and developed ventilation system was then validated based on the 5-day measurements from experimental setup. The overall system performance was simulated and assessed and the PCM thermal energy storage capacity was evaluated. Results showed that the object-oriented Modelica model yields a sufficient accuracy in capturing the thermal behavior of the PCM-based energy storage system. For each stack, the RMSE of predicted PCM temperature compared to measurements are 0.277 °C, 0.332 °C, 0.332 °C and 0.410 °C respectively.