Chapter 6 - Thermal Storage Systems

Abstract

Sensible, latent, and composite thermal storage are the three common thermal storage methods. In light of current studies, research on sensible thermal storage is comparatively mature and has been developed to a commercially exploitative level; however, as the density of sensible thermal storage is low, sensible thermal devices typically have certain limitations due to their large sizes. Although chemical reaction thermal storage has multiple advantages, the chemical reaction process is complex. It sometimes requires catalyzers and has certain safety requirements, and there are other difficulties such as a huge one-time investment and low overall efficiency. Thus it currently remains in the small-scale experimental stage with plenty of problems yet to be solved before any large-scale application. As a superior system, phase-change thermal storage attracts people to carry out extensive studies and enjoys strong development momentum. However, regular phase-change materials (PCMs) used in actual applications are accompanied by various problems, such as inorganic PCM supercooling and phase separation, low-thermal-conductivity organic PCM, and the like, that have severely restricted the application of phase-change technology in solar thermal storage. Furthermore, the reduction of application costs for phase-change thermal storage is a practical problem that must be solved before its large-scale application in solar thermal storage. With the appearance of composite phase-change thermal storage materials, shaped PCMs, functional thermal fluid, and other new types of PCMs in recent years, the foregoing problems are expected to be solved. Research on these new types of PCMs will greatly propel the application of phase-change technology in solar thermal storage.