13. Phase Change Materials and Its Applications

A "phase" is an important physical identity of any material. Pure materials undergo phase transition when the heat is absorbed or released at a constant temperature known as melting or boiling point temperature. This phase transition is associated with "latent heat", which researchers are trying to exploit in multiple ways for different applications. The temperature range for these applications is such that selected materials undergo a phase change. Thus, their latent heat comes into play. There are various applications of these phase change materials (PCMs) from low-temperature passive heating/cooling and thermal management to high-temperature storage for solar thermal systems. PCM implementation requires knowledge of their types, properties, thermal characterization procedure, and property enhancement techniques, to map their suitability for a particular application. An assessment follows their implementation. There are different models for simulating the phase change process for different configurations, for assessing the impact of PCM incorporation. PCM caters to a vast arena of thermal applications and is used for either to enhance thermal cooling performance or to enhance thermal efficiency by wisely exploiting the energy storage potential. Here, we present mathematical modeling and different computational approaches for studying PCM-based systems. The general and most preferred practices in PCMs are discussed along with the different approaches of handling computational grids. Various methods based on discerning the energy equations are discussed along with phase field and volume of fluid methods. Also, the sophisticated commercial/research-based tools available for modeling the phase change materials are detailed. Such a comprehensive overview will be helpful for researchers/engineers looking to realize PCM, especially for energy and building applications.The later part of the chapter provides a comprehensive review of PCMs, followed by a detailed description of various applications and research prospects. This study discusses both heating and cooling applications of PCMs. PCM implementation in buildings can result in energy savings of up to 30%. PCMs application for thermal regulation of batteries, electronic circuits, and photovoltaic module are also discussed. Heat transfer enhancement techniques required to increase PCM dispatch ability, with suitable case studies, have been discussed in detail. The application of PCM in wearable devices to sustain extreme temperatures is still uncharted and can prove to be handy for thermal management and providing sustainable solutions. PCM implementation for solar thermal applications as high-temperature storage material has been discussed in this present study. In summary, this chapter provides a holistic review of different PCM applications and their modeling. It highlights the research, required to be carried out to overcome the shortcomings of PCM implementation to form a feasible solution for various problems. This study also highlights the importance of PCMs in energy conservation, thus contributing to a reduction in CO₂ emissions and climate change.