Transport Properties and Freeze-Thaw Characteristics of Nanofluids

This book presents the rheological and thermal properties and the freeze-thaw characteristics of nanofluids. Nanofluids are dispersions of nano-scale particles (< 100 nm) in a base fluid such as water and glycols. In cold regions, a mixture of 60% ethylene glycol and water by mass (60:40 EG/W) is normally used as the heat transfer fluid due to its low freezing point. Rheological properties of aluminum oxide nanofluid in the EG/W base fluid were investigated and new correlations for viscosity as a function of temperature and particle concentration were developed. From the specific heat experiments on zinc oxide nanofluid a new equation was developed. The thermal conductivity of silicon dioxide nanofluid was measured. A new correlation for thermal conductivity as a function of particle concentration, size, base fluid and particle properties and temperature was proposed, considering the Brownian motion of nanoparticles. Freeze-thaw characteristics of copper oxide nanoparticle dispersions in water were studied experimentally and computationally for a freeze-thaw cycle. The freezing rate, agglomeration of nanoparticles and the effect on the freezing point of nanofluid were summarized.