Date of Award
Master of Science (MS)
Clement C. Tang
Thermophysical properties and rheological behavior of silica (SiO2) nanoparticle colloidal suspension with 9.58% volume concentration in water were analyzed. The laminar flow of the fluid through tubes of different diameter was studied to compare its pressure drop and heat transfer performance with those of water.
Thermal conductivity of the silica suspension was found to be 0.99% to 3.6% higher than the same property of water when measured from 7Â°C to 50Â°C. Within the temperature range, thermal conductivity of the silica suspension and water increased by 9.88% and 11.1% respectively, with increase in temperature.
It was observed that the colloidal dispersion of silica behaved as non-Newtonian shear thickening fluid whose viscosity increased with increasing shear rate when temperature was kept constant. Power law model for non-Newtonian fluid could fairly predict the viscosity of the fluid at certain shear rate. While measuring viscosity data with a rotary viscometer at fixed shear rate and temperature, the fluid viscosity showed a change in value with time for first 12-15 second of shear application and then obtained a constant value.
Pressure drop analysis showed that the friction factor of the silica suspension and the friction factor of water have no significant difference after a Reynolds number of 750. Before that, silica suspension has higher friction factor than that of water and the highest increase observed was 63%. Conventional correlation to predict the friction factor of single phase fluid can also be used in case of silica colloidal dispersion. As the diameter of the test section got smaller, the increase in the friction factor of silica dispersion enhanced compared to the friction factor of water.
There was no eminent difference between the heat transfer performance of silica suspension and water. Correlation that is used for water was found to be suitable for nanoparticle dispersion too. The highest value of Nusselt number for silica suspension and water was 17.54 and 13.42 respectively, when the fluids were circulated through the tube with the biggest diameter.
Sharif, Md Tanveer, "Experimental Investigation Of Thermophysical Properties, Pressure Drop And Heat Transfer Of Non-Newtonian Silica Colloid Flow In Tubes" (2015). Theses and Dissertations. 1834.