Experimental investigation of tracer diffusion coefficient of tert‐butanol in water‐based silica nanofluids

Tracer diffusion coefficient of tert‐butanol in water‐based silica nanofluids was measured by using pulsedfield gradient nuclear magnetic resonance (PFG‐NMR) method for silica nanoparticle volume fractions ranged from0.005% to 1% at three different temperatures (15, 25 and 35°C). Nanofluids were prepared by dispersing hydrophilicsilica nanoparticles with an average size of about 7–14 nanometer in deionized water without adding any surfactant orstabilizing agent. In this work, formation of dye–nanoparticle complexes was minimized and undesirable primaryadvection effects induced by solute injection were also eliminated. Insignificant enhancement (mostly less than 10%increase) in tracer diffusion coefficient of tert‐butanol in nanofluids was observed. These results indicate that probablyBrownian motion of nanoparticles and induced micro‐convection tend to enhance mass transfer but the obstructioneffect of solid nanoparticles limits this enhancement by reducing the free volume face to diffusion path of molecules.

کلیدواژه ها:

nanofluid ، silica nanoparticles ، mass diffusion coefficient ، PFG-NMR