Particle size and interfacial effects on thermo-physical and heat transfer characteristics of water-based α-SiC nanofluids

TLDR

The study investigates how particle size affects the macroscopic properties and heat transfer of α‑SiC/water nanofluids, discusses criteria for evaluating performance, and suggests optimal development directions. Particle sizes ranging from 16 to 90 nm were varied based on specific surface area, and heat‑transfer coefficients were measured and compared to base fluids and literature nanofluids. Larger particles yield higher thermal conductivity and smaller viscosity increases due to reduced solid/liquid interfacial area, while viscosity can be significantly lowered by adjusting suspension pH independently of thermal conductivity.

Abstract

The effect of average particle sizes on basic macroscopic properties and heat transfer performance of α-SiC/water nanofluids was investigated. The average particle sizes, calculated from the specific surface area of nanoparticles, were varied from 16 to 90 nm. Nanofluids with larger particles of the same material and volume concentration provide higher thermal conductivity and lower viscosity increases than those with smaller particles because of the smaller solid/liquid interfacial area of larger particles. It was also demonstrated that the viscosity of water-based nanofluids can be significantly decreased by pH of the suspension independently from the thermal conductivity. Heat transfer coefficients were measured and compared to the performance of base fluids as well as to nanofluids reported in the literature. Criteria for evaluation of the heat transfer performance of nanofluids are discussed and optimum directions in nanofluid development are suggested.