Heat Transfer Augmentation Techniques for Phase Change Materials

Phase change materials (PCMs) have a high potential for thermal storage because they can absorb and release a large amount of heat. In PCMs, the heat transfer rate is relatively low because of the low thermal conductivity of PCMs, which limits the performance of latent thermal energy storage systems. To improve the thermo-physical properties of PCMs, various methods can be categorized into two groups: heat transfer enhancement methods and thermal conductivity enhancement methods. Furthermore, heat transfer enhancement methods can be divided into passive and active techniques. The present chapter presents the passive techniques such as extended surfaces, multiple PCMs, composite PCMs, and encapsulation, as well as active techniques such as magnetic fields, electric fields, mechanical vibration, and ultrasonic waves, on the melting and solidification processes of PCMs. Additionally, a general overview of the heat transfer enhancement of PCMs with remarks on the advantages and disadvantages with a practical approach is provided.