Solid thermal storage with PCM materials. Numerical investigations

Thermal energy storage systems in solid state are the next generation of solar power plants which bring a substantial optimization in the energy production; they compensate for the gap between the availability of solar irradiation and the electricity demand by an endowed heat storage. The proposed research is aimed to analyse the coupled behaviour of concrete including PCM (Phase Change Materials) particles employed as solid energy storage media, even emphasizing the relevance of analyses at the mesoscale level. A study on the increased thermal capacity in Thermal Energy Storage (TES) concrete solids with inclusions of PCM is developed within this paper. Particularly, the change in thermal behaviour of such composites by varying the inclusions percentage is assessed. Transient thermal analyses are conducted by considering a homogenized composite; a uniform distribution of PCM, obtained during mixing of fresh concrete, is assumed within the cementitious matrix. Additionally, the change in mechanical strength of such a material is analytically and numerically investigated, both at room temperature and during heating. 3D mechanical FE models are also developed at the meso-scale level to explicitly represent the main concrete components such as cement paste, coarse aggregates, and PCM to better describe the evolutionary process of thermal damage - if occurring - during plant functioning. (C) 2017 Elsevier Ltd. All rights reserved.