Experimental investigation of the thermal performance of functional magnetic nanofluids

• Main Author: Yeo, Hao Wen
• Other Authors: Wong Teck Neng
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/78607
• Institution: Nanyang Technological University

This Final Year Project involves the experimental investigation of functional nanofluids and thermal paste with nanoparticles to determine their natural convection heat transfer performance and thermal conductance. A Linear Heat Conduction Unit was setup to determine the nanofluid/ thermal paste thermal conductance whereas a new test cell was design and developed to obtain the natural convection heat transfer coefficient of the nanofluids. Nano-size particles are suspended in base fluid such as water to form nanofluids and magnetic nanoparticles are used. Using an external magnetic field, this project also explores the possibility to induce mixing of the magnetic nanofluids for enhanced heat transfer. Different fluids were placed in the linear heat conduction unit and upon reaching steady state, temperature values were taken and evaluated into thermal conductance. The fluids that were used in the first test of thermal conductance showed that less viscous fluids have high conductance but will quickly lose its thermal conductance when the base fluid evaporates. Fluids that are paste-like have slightly lower thermal conductance but able to last longer as compared to less viscous fluids. For the natural convection heat transfer experiments, the nanofluid was placed inside a cubical cavity with hot and cold side and tested under the effect of rotating magnets outside the test cell. Using the temperatures was taken on both the hot and cold side, the natural convection heat transfer coefficients of different nanofluids were determined and their Nusselt numbers were computed. The effects of Rayleigh number on the Nusselt number of the nanofluids were evaluated and the results show that iron oxide encapsulated in silica produced a better trend as compared to 0.0017% carbon black nanoparticle concentration and water. Under the influence of a magnetic field, the heat transfer of the ferrofluid does not show any enhancement. More test needs to be done with different parameters and taking into consideration of Hartmann number and Lorentz forces are required. Nanofluids show potential in enhancing thermal performance at a microscopic level. However, there is need to research and experiment on different parameters and variations of nanofluids to maximise the thermal capabilities.