Nano-enhanced phase change materials and fluids in energy applications: A review

This paper provides a review of nano-enhanced phase change materials (NEPCM) and nanofluids incorporated in experimental systems, i.e. different applications. The effect of the added nanomaterials on the main thermal properties was also discussed and analyzed in detail. According to the provided review, it was found that the addition of nanoparticles improves specific thermal properties of nano-enhanced materials. The thermal conductivity can be increased by between 20% and 100%, with respect to the base fluid. Other general thermal properties are slightly reduced such as latent heat, while for specific heat capacity the results are variable. Regarding applications, thermal energy storage systems as well as cooling systems for photovoltaics (PV-NEPCM) were investigated the most based on the existing literature. The gained results revealed that important data are missing and are related to the general preparation process of nano-enhanced materials. The economic as well as environmental evaluation of nano-enhanced systems is not covered well and addressed in the existing research findings. Safety issues and guidelines for handling nano-enhanced materials are also not properly addressed in the existing literature. Specific issues and future research directions were also discussed and linked with implementation of nanomaterials for considered applications and circumstances.