Chapter 15 - Nanoencapsulated phase change materials for solar thermal energy storage

Abstract

Renewable energy resources come in high demand due to the scarcity of conventional energy sources and associated pollutions. However, the inadequacy of solar power in nonsunshine hours gave rise to the need for thermal energy storage, and the stored thermal energy or heat using a storage media can be released during off-peak hours, known as peak shifting. Phase Change Materials (PCM) based thermal energy storage systems perform comparatively well with good efficiency, with other advantages including low weight per unit storage capacity, retrieval or reversible cycles, and ecofriendly ways to reuse natural energy. However, a major limitation of PCM is poor thermal conductivity and diffusivity. Other problems plaguing most PCMs include phase separation, supercooling, corrosion, volume expansion, and leakage during phase transition. Incorporation of nanoparticles that possess a high surface area to volume ratio, controlled volume expansion, reduced reactivity with the external environment, and high heat transfer rate helps PCM to enhance its thermal conductivity. This work focuses on incorporating different wt.% nanoparticles in PCMs and core-shell confinement, and several organic and inorganic shell materials would be adopted to encapsulate PCM core with different nanoporous scaffolds to confine most of organic PCMs. Optimization of the nanoparticle concentration will aim to enhance PCM’s thermal conductivity without compromising the storage capacity of PCMs. Furthermore, the different parameters like nanoparticle concentration, rate of mass flow, thermophysical properties of nanoparticles, and transition temperature have a significant impact on increased thermal conductivity and thermal energy storage capacity, resulting in low power consumption. Owing to their unique properties of absorbing and releasing heat energy, PCMs are useful for customized applications as per demand, mainly for solar heaters and solar coolers to build comfortable living materials.