Experimental investigation of thermal and rheological behavior of hexagonal boron nitride nanofluids

In this study, thermal and rheological behavior of nanofluids prepared with hexagonal boron nitride (hBN) nanoparticles is the main interest. hBN is a ceramic material with high thermal conductivity and superior chemical stability that makes it a suitable candidate for nanofluid synthesis. Additionally, it has an orthotropic thermal conductivity which encourages study on their behavior within nanofluids. The studies that focus on hBN nanofluids are mostly limited to hBN-oil dielectric nanofluids. However, using hBN with other base fluids has also significant potential applications. This study focuses on stability, rheological and thermal behavior of hBN-water and hBN-ethylene glycol (EG) nanofluids that have not been investigated in detail. Thermal and rheological behaviors of nanofluids prepared either with pH control or surfactant addition have been investigated, and reported for different volume concentrations. All prepared nanofluids exhibit Newtonian behavior. Due to particle loading to the base fluid, viscosity increase has been observed within nanofluids as expected. Surfactant addition clearly results in higher viscosity increase and lower thermal conductivity enhancement within nanofluids comparing to ones prepared with pH control. Thermal enhancement for hBN nanofluids is found to be better than the one for Al2O3 nanofluids.