Study of heat transfer properties of nanofluids.
Ong, Wu Jie.
Date of Issue2009
School of Mechanical and Aerospace Engineering
The development of nanotechnology has led to the creation of nanofluids. Nanofluids are stabilised mixtures consisting of solid particles (in nano sizes) that are being well dispersed and suspended in base fluids. Being a stable mixture, there were reports of improved thermal properties of the nanofluid. Having the potential to replace existing conventional cooling methods in industrial applications, numerous experiments were conducted. However, conflicting results were reported. Also, the heat mechanisms attributed to the enhanced thermal properties of the nanofluid remain ambiguous despite some models were derived. This report investigates the thermal properties of gold nanofluids using the transient single-wire technique for measuring the thermal conductivity of the nanofluids. The investigation will take into consideration of the volume concentration which is believed to be a factor influencing the thermal properties of the nanofluid. Judging from the experimental results on the thermal conductivity values of different gold nanofluids, there are significant enhancements. For gold nanofluid samples with relatively small volume concentrations of 0.000545% and 0.00109%, there are enhancements of 4.9% and 11.4% respectively at a temperature of 20°C. The most significant enhancement recorded is 12.7% for the gold nanofluid sample which has a small volume concentration of 0.00029% Au, with Poly(vinylpyrrolidone) in water (i.e. aqueous solution) as its base fluid. From the measured readings on the viscosity of nanofluids, it show that viscosity value of the nanofluids increases as the volume ratio of the nanoparticles in the fluid rises Although it is desired to have a larger thermal conductivity value by having a larger volume ratio of nanoparticles to facilitate heat transfer, one has to also take into consideration the viscosity value since the nanofluids get more viscous with larger volume ratio, which could be undesirable for the fluids to flow in channels or pipes for heat transfer.
Final Year Project (FYP)
Nanyang Technological University