A simple model for latent thermal energy storage systems with encapsulated phase-change material

Efficient thermal energy storage systems are called to be a key part of any successful transition to a net zero future. Latent thermal energy storage provides high energy density but a low power rate, though solutions such as encapsulated phase-change materials address this issue by increasing the heat exchange surface area between the heat transfer fluid and the phase-change material. However, such devices still present challenges in their performance that hinder their widespread commercialisation, so the development of fast and accurate mathematical models is key to speed up the process. In this article we derive a simple physics-based model, the Averaged Capsule Model (ACM), that has similar accuracy to the state-of-the-art models but a significantly lower computational cost. We also clarify some misunderstandings about this kind of models common in the literature, and provide an open-source implementation of the models. Due to its low computational cost, this novel model opens the door to real-time control and design optimisation of thermal energy storage devices, which are key to accelerate the commercialisation of such technologies. • A reduced model for encapsulated energy storage system is provided. • Compared to state-of-the-art, the model has similar accuracy and runs 100x faster. • Common misunderstanding in literature models are discussed and clarified. • An implementation of the model is provided under an open-source licence.