Search

Considering equipment damage, energy consumption enhancement and efficiency reduction during undesirable solidification process, this paper experimentally investigated the ability of clay nanoparticles to hinder the solidification procedure. The nanofluids were prepared by dispersing various concentrations of clay nanoparticles (0.01 wt.%, 0.02 wt.% and 0.04 wt.%) in deionized water without any dispersants. The solidification characteristics of nanofluids were determined by using cooling generator system. The experimental results of clay nanofluids showed a reduction in the nucleation temperature and an enhancement of supercooling degree of about 25% during solidification process due to reduction in heat transport properties. According to the comparison results, it was construed that providing supercooling condition, lower density nanoparticles are more able to advance in nucleation phenomenon and also higher thermal conductivity nanoparticles have more tendency to reduce supercooling degree. Therefore, considering desirable and undesirable solidification, the best possible candidate of nanoparticles can be utilized based on their thermophysical properties. [ABSTRACT FROM AUTHOR]

In this study, the influence of Zirconia (ZrO 2 ) and Titania (TiO 2 ) nanopaticles on liquid–solid phase transition of aqueous nanofluids with/without Poly vinyl pyrrolidone as surfactant are experimentally compared. A cooling generation apparatus based on the compression refrigeration cycle has been used to explore the solidification behavior of nanofluids as phase change materials. The experimental results show that ZrO 2 and TiO 2 nanoparticles considerably reduce the solidification supercooling degree of deionized water (as basefluid). Only adding 0.04 wt% ZrO 2 and TiO 2 nanoparticles to base fluid, the percentage of reduction in supercooling degree attained 81% and 65%, respectively. The results reveal that although the presence of surfactant in nanofluids reduces the supercooling degree and slightly solidification time of both ZrO 2 and TiO 2 nanofluids; but it has no influence on onset nucleation time. Comparison of ZrO 2 and TiO 2 nanofluids with/without surfactant presents that ZrO 2 provides faster solid layers formation and has more energy saving potential in storage systems due to its lower supercooling degree. [ABSTRACT FROM AUTHOR]