Thermophysical and dielectric profiles of ethylene glycol based titanium nitride (TiN–EG) nanofluids with various size of particles
Abstract
In this study, thermophysical properties such as thermal conductivity, rheological behavior and surfacetension of ethylene glycol (EG) based nanofluids containing titanium nitride (TiN) nanoparticles with volumefraction ranging from 0.0022 to 0.0111 and with various nanoparticle sizes have been experimentallyinvestigated at constant temperature. In addition, dielectric properties of these nanofluids werealso measured at same temperature and discussed in detail. It is shown that nanoparticle contentincrease leads to similar trends for nanofluids properties, while nanoparticle size has different effect followingthe studied property. Actually, thermal conductivity and surface tension of nanofluids are higherwith smaller nanoparticles for same nanoparticle content. Following the nanoparticle content, a transitionfrom Newtonian nature of nanofluids to shear-thinning yield stress material with viscoelastic structureoccurs. Lower the nanoparticle size, higher is the viscoelastic structure and the yield stress whenthey are present. Thixotropy of the nanofluids was also reported and depends both on concentrationand size of nanoparticles. Both dielectric properties and electrical conductivity of TiN–EG nanofluidsincrease with nanoparticle content and are higher for suspensions containing bigger nanoparticles.Moreover, experimental data for thermal and electrical conductivities enhancement were modeled andcompared to existing correlations, simple linear relationships were also proposed considering the effectof nanoparticle content and average size.