Systematic review of encapsulation and shape-stabilization of phase change materials

In the development of renewable energies, thermal energy storage (TES) has become a key opportunity to relieve to some extent the increase in energy demand and supply. The past two decades have seen increasingly advances in the field of phase change materials (PCM) as latent heat storage systems, being one concern their containment when using solid to liquid PCM. The purpose of this paper is to review the state-of-the-art of shape-stabilization (SS-PCM) and encapsulation (CS-PCM) of organic PCMs for low thermal applications (<100°C) and provide a comparison between them. Moreover, the review was designed to assess the insights about where the current research on CS-PCM and SS-PCM is heading and discuss the gaps that are still needed to overcome. The paper has been divided in two parts. The first part deals with a bibliometric analysis and literature maps about the countries, authors, keywords and co-authorship of SS-PCM and CS-PCM in the last forty years. The second part consist in a systematic survey of different materials and processing methods found in literature, corresponding to encapsulation and shape-stabilization of organic phase change materials. The results of this review shown several production techniques, including chemical synthesis for core-shell composites, vacuum impregnation methods for shape-stabilized PCMs, hierarchical templates for designing porous supports and fiber-based PCM composites by means of electrospinning techniques. As well, the containment materials vary from organic to inorganic compositions allowing a wide range of chemical compatibility with other materials when applied. Nevertheless, is worth to notice that characterization such as percentage of leakage, thermal reliability, thermal conductivity, thermal cycling and durability are still missing in most of the investigations. This is an opportunity for future works to keep closing the gaps regarding SS-PCMs and CS-PCMs.