Dispersion stability and thermal conductivity of propylene glycol-based nanofluids

TL;DR

This study investigates the stability and thermal conductivity of propylene glycol-based nanofluids with Al2O3 and TiO2 nanoparticles, revealing temperature effects on particle size and non-linear conductivity enhancement.

Contribution

It demonstrates stable nanofluids with temperature-independent thermal conductivity enhancement and compares experimental results with theoretical models, highlighting aggregation theory as most accurate.

Findings

Nanofluids are stable across 20-80°C.

Particle size decreases with temperature.

Thermal conductivity increase is non-linear with concentration.

Abstract

The dispersion stability and thermal conductivity of propylene glycol based nanofluids containing Al2O3 and TiO2 nanoparticles were studied in the temperature range of 20 to 80 {\deg}C. Nanofluids with different concentrations of nanoparticles were formulated by the two-step method without use of dispersants. In contrast to the common belief the average particle size of nanofluids was observed to decrease with increasing temperature. The nanofluids showed excellent stability over the temperature range of interest. Thermal conductivity enhancement for both of studied nanofluids was a non-linear function of concentration while was temperature independent. Theoretical analyses were performed using existing models and comparisons were made with experimental results. The model based on the aggregation theory appears to yield the best fit. Keywords: Nanofluids, Propylene glycol, Alumina nanoparticles, Titania nanoparticles, Thermal conductivity, Dispersion stability.