Solidification behaviors of water-based nanofluids

Titanium dioxide (TiO2) nanoparticles, carbon nanotubes (CNT) and graphene nanoplates were chosen to prepare water-based nanofluids. The solidification processes of graphene/water, CNT/water and TiO2/water nanofluids were measured by the cooling curve method. Effects of nanomaterial shape, size, contact angle and specific surface area on the supercooling degree, starting time and total time of solidification of water were investigated. It was found that graphene nanoplates and TiO2 nanoparticles had the strongest and weakest effects on decreasing the supercooling degree and solidification times of water, respectively. Graphene nanoplates of 0.034wt% eliminated the supercooling phenomenon of water completely, and reduced the starting time and total time by 61.22% and 30.53%, respectively. Analysis of nucleation revealed that the supercooling degree of nanofluid was mainly dependent on the total surface area of nanomaterials exposed to water. Compared to the contact angle, shape and size of nanomaterials, the specific area of nanomaterials was more important to the supercooling degree of nanofluid.