Preparation of novel microencapsulated phase change material with Cu-Cu2O/CNTs as the shell and their dispersed slurry for direct absorption solar collectors

Abstract In this study, a novel microencapsulated phase change material paraffin@Cu-Cu 2 O/CNTs was successfully prepared by hydrothermal reduction and in situ deposition method, in which paraffin as the core, Cu, Cu 2 O and carbon nanotubes (CNTs) as the shell. SEM and TEM results proved that the microcapsules have a core-shell structure, the CNTs were irregularly wrapped on the shell, and the diameter of the microcapsules was about 600-800 nm. The melting temperature and latent heat of the paraffin@Cu-Cu 2 O/CNTs microcapsules were 61.17 °C and 81.31Jg -1 , respectively, and the encapsulation rate of the microcapsules was calculated to be 41.53% from the results of the DSC measurement. Due to the shell material, the paraffin@Cu-Cu 2 O/CNTs microcapsules displayed excellent thermal stability, its thermal decomposition temperature is increased by 97 °C compared to paraffin. Moreover, the paraffin@Cu-Cu 2 O/CNTs microcapsules were dispersed in water to form a new kind of slurry, such fluid exhibited great improvement in terms of thermal conductivity, specific heat capacity, light absorption performance and photo-thermal conversion efficiency than that of paraffin@Cu-Cu 2 O microcapsules slurry. Therefore, the high heat storage capability and excellent photo-thermal conversion performance of the paraffin@Cu-Cu 2 O/CNTs microcapsule slurry make it to be the most potential heat transfer fluid for direct absorption solar collector.