Investigation of Stability of Water Based MWCNTs Nanofluids and Size Distribution of MWCNTs Functionalized by Different Chemical Treatment Processes

Abstract

Recently the study on the convective heat transfer properties of the nanofluids has gained remarkable importance. Nanofluids are stable dispersions of nanoparticles into a base fluid. These are experimentally found to possess enhanced mechanical and heat transfer properties compared to the parent base fluid. Previous studies confirm that of all the nanofluids, the ones prepared using MWCNTs with distilled water as the base fluid produced a maximum enhancement in the thermal conductivity of the dispersant. This widens the potential scope of MWCNTs nanofluids as coolants in different applications. Despite its exceptional properties, preparation of a stable water based MWCNTs nanofluid often involves a tedious process because of their hindrance to disperse in organic solvents. Functionalization is the process of surface modification of CNTs to reduce their hydrophobicity thereby improving their dispersion effect in organic solvents. Functionalization by chemical treatment is the most effective method in maintaining the long term stability of the nanofluids, but these processes often involve treatment with strong chemicals which affects the size distribution and morphology of the carbon nanotubes. The current study investigates the stability and particle size distribution of MWCNTs nanofluids functionalized by different processes and reports the most effective process for functionalization of MWCNTs.

Performance investigation and exergy analysis of vapor compression refrigeration system operated using R600a refrigerant and nanoadditive compressor oil

“…This poses the chances of coagulation and flocculation in the refrigerant fluids. The samples with zeta potential value more than +30 mV and lesser than -30mV are considered to be more stable [27]. The zeta potential values of various nanolubricant samples can be shown in tab.…”