Experimental analysis on dynamics of liquid molecules adjacent to particles in nanofluids

Hashimoto, Shunsuke*; Nakajima, Kenji  ; Kikuchi, Tatsuya*  ; Kamazawa, Kazuya*; Shibata, Kaoru  ; Yamada, Takeshi*

Quasi-elastic neutron scattering (QENS) and pulsed-field-gradient nuclear magnetic resonance (PFGNMR) analyses of a nanofluid composed of silicon dioxide (SiO) nanoparticles and a base fluid of ethylene glycol aqueous solution were performed. The aim was to elucidate the mechanism increase in the thermal conductivity of the nanofluid above its theoretical value. The obtained experimental results indicate that SiO particles may decrease the self-diffusion coefficient of the liquid molecules in the ethylene glycol aqueous solution because of their highly restricted motion around these nanoparticles. At a constant temperature, the thermal conductivity increases as the self-diffusion coefficient of the liquid molecules decreases in the SiO nanofluids.