Experimental and numerical investigation of melting/solidification of nano-enhanced phase change materials in shell & tube thermal energy storage systems

In this work, the melting/solidification process of the nano-enhanced phase change materials (NePCM) was investigated experimentally and numerically using a horizontal shell & tube heat exchanger equipped with longitudinal fins. The NePCM was prepared by dispersing titanium dioxide nanoparticles (TiO2NPs) in stearic acid (SA). The effect of geometry parameters and nano particle content on melting/solidification rate of PCM were investigated. The results showed that using longitudinal fins could reduce the required time for melting and solidification by around 54% and 76%, compared to the system without fins, respectively. while the greatest effect of adding the TiO2-NPs was related to unfinned tube heat exchanger, which reduced the required time by 6% and 8% for melting and solidification, respectively. Furthermore, it was concluded that adding nanoparticles could offer its positive effect for enhancing the melting rate only while using unfinned tube heat exchanger.