Modelling and simulation of a Latent Heat Thermal Energy Storage

The transformation of the global energy system in line with the Paris Agreement requires rapid uptake of renewables throughout all kinds of energy use. As a result the low-carbon heating technologies are growing, but the energy demand is still mostly met by fossil fuels. In order to accelerate a wider transition to renewable energy solutions in the heating sector, thermal energy storage (TES) technologies can be used. TES help to integrate high shares of renewable energy in power generation, industry and buildings. Several energy storage options exist now, but the one that has gained increasing attention and is topic of interest in this thesis is the latent heat thermal energy storage (LHTES) because it offers considerably higher energy density at a nearly constant temperature level if compared to sensible storage systems. These features are particularly interesting in the urban context, where limited installation space is required for TES units. Despite its considerable potential, market deployment has only been achieved by a restricted number of commercial devices. This may be related to two principal conditions: firstly the lack of accurate and at the same time fast models, which would facilitate LHTES integration in energy systems; secondly the limited knowledge on how full scale LHTES devices interact with the heating systems in which they are incorporated. This thesis tries to overcome the former problematic by implementing a fast and accurate model for system-level simulations of shell-and-tube latent heat storage units. Such a model is entirely based on a-priori known physical and geometrical parameters. Different fins geometries are analysed while considering also different materials for the phase change material (PCM) used to store the thermal energy. In order to achieve a better accuracy for the model with respect to a more realistic three dimensional one, the effect of such variables are considered thanks to the definition of a few parameters, which are mainly focused on the geometrical properties of the fins as well as the thermal properties of the selected PCM.