TY - CONF
T1 - Dispersion stability of CNT and CNT/metal-based nanofluids
AU - Sezer, Nurettin
AU - Koç, Muammer
PY - 2018
Y1 - 2018
N2 - The anomalous enhancement of thermal conductivity, obtained by dispersing small concentration of solid nanoparticles into the conventional heat transfer fluids, attracted the researchers’ interest all over the world. The special attention on nanofluids for heat transfer has still been growing to attain highest enhancement using different type of nanoparticle materials. Among them, carbon nanotubes (CNTs)-based nanofluids exhibited superior thermal conductivity enhancement. However, the major problem encountered with CNT-based nanofluids is maintaining the colloidal stability. Although a decent stability is the vital property of a nanofluid to maintain its enhanced thermal properties, hydrophobic nature of CNT surfaces and strong Van-der Waals interactions between the nanotubes cause aggregation and subsequently weak dispersion stability in fluids. Various methods, such as acid treatment and thermal treatment of CNTs, have been developed to functionalize and stabilize the dispersion of CNTs in fluids. Despite the success of stability enhancement at certain extend, applied functionalization methods are usually reported to severely destroy the structure of CNTs and adversely affect the thermal conductivity of the nanofluids. An alternative method of stabilization is surfactant addition. When dispersed into the solution, surfactants are physically adsorbed on CNT surfaces to convert the surface characteristics into hydrophilic nature without effecting the CNT structure. This study aims to investigate the effect of surfactant type and concentration on dispersion stability of CNT-based nanofluids. The study is extended with the decoration of CNTs with metal nanoparticles (Fe, Zn and Ag) and investigating the effect of immobilized metals on dispersion stability of CNTs. The results revealed that more stable nanofluids are attained with a zeta potential of 26.7 mV using acacia gum at 0.5:1 – 1:1 surfactant:CNT weight ratio. The nanofluids of metal decorated CNTs exhibited less stability compared to the acacia gum-stabilized nanofluids.
AB - The anomalous enhancement of thermal conductivity, obtained by dispersing small concentration of solid nanoparticles into the conventional heat transfer fluids, attracted the researchers’ interest all over the world. The special attention on nanofluids for heat transfer has still been growing to attain highest enhancement using different type of nanoparticle materials. Among them, carbon nanotubes (CNTs)-based nanofluids exhibited superior thermal conductivity enhancement. However, the major problem encountered with CNT-based nanofluids is maintaining the colloidal stability. Although a decent stability is the vital property of a nanofluid to maintain its enhanced thermal properties, hydrophobic nature of CNT surfaces and strong Van-der Waals interactions between the nanotubes cause aggregation and subsequently weak dispersion stability in fluids. Various methods, such as acid treatment and thermal treatment of CNTs, have been developed to functionalize and stabilize the dispersion of CNTs in fluids. Despite the success of stability enhancement at certain extend, applied functionalization methods are usually reported to severely destroy the structure of CNTs and adversely affect the thermal conductivity of the nanofluids. An alternative method of stabilization is surfactant addition. When dispersed into the solution, surfactants are physically adsorbed on CNT surfaces to convert the surface characteristics into hydrophilic nature without effecting the CNT structure. This study aims to investigate the effect of surfactant type and concentration on dispersion stability of CNT-based nanofluids. The study is extended with the decoration of CNTs with metal nanoparticles (Fe, Zn and Ag) and investigating the effect of immobilized metals on dispersion stability of CNTs. The results revealed that more stable nanofluids are attained with a zeta potential of 26.7 mV using acacia gum at 0.5:1 – 1:1 surfactant:CNT weight ratio. The nanofluids of metal decorated CNTs exhibited less stability compared to the acacia gum-stabilized nanofluids.
M3 - Paper
ER -