Development of a high thermal energy storage device with Form-Stable Phase Change Materials (FPCMs)

The need for reduction of fossil fuel exploitation along with their emissions as well as the urgency of coping with the latest challenges arose in the energy sector in the last decades to sustain and to make the well-known renewables more resilient, have pushed towards the development of new TES solutions. The manufacturing of Form-Stable Phase Change Materials (FPCM) offer a sustainable, clean, flexible and compact option for collecting thermal energy thanks to their ability of storing higher energy density contents compared to the traditional sensible energy storage-based solutions and proving to be a more effective option for a wider range of temperature applications. The selection, mixing and compressing of a Solar Salt eutectic mixture with a supporting material and a carbon-based component allowed the thermal properties enhancement and, at the same time, the controlled sintering procedure prevented the typical leakage issues of common PCM-based solutions confirming the replicability of the whole procedure. In this no emissions-driven panorama, this study offers a comprehensive overview of the thermo-physical and microstructural investigation of the FPCMs. Main focuses of the present study have been: the assessment of a reliable thus replicable manufacturing procedure to fabricate the pellets, the investigation on the shape-stability concept connected to the FPCMs in order to find the links between micro-structural features and thermal performances, the development of a parallel digital imaging technique to assess, compare and validate in an unbiased and independent way the reliability of some structural results obtained with existing technologies for the characterization of the samples studied. Differential Scanning Calorimetry (DSC) and Laser Flash Analyzer (LFA) have been adopted for thermal characterization of six starting formulations selected for the analysis. In a second stage, the complementary use of Scanning Electron Microscope (SEM) and X-Ray micro-tomography (XRT) allowed to shed a light onto the morphology and topology of the shape-stabilized tablets manufactured based onto three final and more performing formulations. The purpose of this study has then been twofold: the experimental characterization of the materials involved into a micro-scale investigation and a device-scale preliminary evaluation of some key performance indicators related with the application of FPCMs with some suggestions for further and more detailed performance-based analysis. An added value to the scientific literature consists on increasing the knowledge on FPCMs filling the present gaps for what thermo-physical properties are concerned as well as to offer a different perspective and insights onto the testing and manufacturing procedure adopted to help developing such new solutions in order to walk their commercialization into the market and to allow decision e policy-makers to favour their production for a future wide applicability range.