Improved Thermal Response in Encapsulated Phase Change Materials by Nanotube Attachment on Encapsulating Solid

Abstract

This paper demonstrates greatly improved specific power (W/g) for encapsulated phase change materials (EPCM) as a result of modified interface morphology. Carbon nanotubes are strongly attached to the interior walls of the graphitic foam encapsulation. Microstructure analysis using scanning electron microscopy (SEM) indicates that the wax infiltrates into the carbon nanotubes (CNT) forest and creates an intimate contact with increased interfacial area between the two phases. Specific power has been calculated by measuring thermal response times of the phase change materials using a custom system. The carbon nanotubes increase the specific power of the encapsulated phase change materials by about 27% during heating and over 146% during the more important stage of latent heat storage. Moreover, SEM images of the interface after repeated thermal cycling indicate that the presence of CNT may also improve durability of the EPCM by preventing interfacial gaps and maintaining improved contact between the graphite and PCM phases.