Abstract:
Effect of preparation methods of NFs, influence of concentrations of NPs into the base fluids, and outcomes by adding different kind of surfactant on dispersion stability of NFs for the enhancement of thermal transport properties is considered for this research. Synthesis of TiO2 NPs is done via the sol-gel process using Titanium tetra-isopropoxide (TTIP) as a precursor and acetic acid as a solvent, TiO2 NPs are also prepared from bulk Titania powder as a starting material and characterized through different characterizing techniques. Thermal stability of NPs is investigated via TG/DTA curve and TiO2 NPs annealed at 400 oC are found to be more thermally stable as compared to as prepared sample and sample obtained from bulk Titania and annealed at 400 oC. NFs are prepared by the dispersion of different concentrations of titanium dioxide NPs (which was annealed at 400 oC) into the working fluid via sonication as well as stirring techniques separately, using DI water as a base fluid. Suspension stability of these NFs is analyzed through UV-VIS Spectrometer and examined the absorbance spectrum for one week, obtained from various concentration. Stability of NFs is further examined, taking the two most stable concentration (0.07 vol. % and 0.1 vol. %) from all, by adding two different kinds of surfactant (i.e. SDS and PVA) in it. UV-VIS spectroscopy results revealed that stability of NFs increased by the addition of a surfactants and it also tends to increase with the increase of nanoparticles concentration. The addition of surfactant reduces the clustering of NPs by lowering the surface tension in heat transfer fluids near its surface, hence maximizing the benefits in terms of dispersion stability. Stable suspension of NFs is observed by examining the one month testing results with the addition of a surfactant, which is best suitable for low-temperature thermal energy applications.
