**7. Conclusion**

Microencapsulation is a promising technology to fabricate PCM microcapsules for thermal energy storage and other versatile applications. Microencapsulation technology not only overcome the problem of leakage, volatilization and handling the difficulty of liquids PCMs but also improve the heat transferring ability of PCMs and thus makes them a favorable means for many broad range of applications. The thermal, physical, chemical and mechanical properties of PCM microcapsules are highly dependent on the type of the core materials, shell materials and synthesis processes. Encapsulation with inorganic shells can provide more advantages for microencapsulated PCMs and therefore will gain much more attention from fundamental research to commercial development in the future. The designing parameters, such as weight

ratio of raw materials for core and shell, the selection of dispersion medium, reaction temperature, time, agitation speed, particles size and its distribution and other additives should be carefully addressed to obtain PCMs microcapsules with well-defined core-shell structured and good thermal energy-storage capability. Though PCM microcapsules are considered smart thermal energy storage materials, still much more new materials and synthetic techniques are to be explored to offer numerous possibilities for the design and fabrication of innovative bi- and multi-functional PCMs microcapsules with better properties and functions than the traditional ones.
