The Effect of Water-Based Nanofluid Incorporating Al₂O₃ Nanoparticles on Heat Pipe Performance

This study is considering the impact of nanoparticles deposition on the heat pipe (HP) wick porosity after several use of nanofluid as a working medium. Water based nanofluids with 1, 2 and 3 vol% alumina nanoparticles are prepared and characterized. These nanofluids are charged to a complete vacuumed copper heat pipe made out of copper tube and lined by a porous wick. The heat pipe is equipped with a vacuum pressure and temperature sensors for assessing its performance under different operating conditions. At the beginning, the heat pipe performance showed a significant enhancement for using the nanofluids over the pure water. This enhancement is later depreciated after several used and raised the concern of the stability of the nanoparticles suspension stability in the base fluid due to the phase change of the water. Scan electron microscope (SEM) images are taken for the heat pipe wick after repetitive use; the images revealed a deposited layer of aggregated nanoparticles on the wick mesh surface. These particles aggregations developed a serious capillary and thermal resistance which in turn impacts the heat pipe performance. A particles propellant wick design must be considered when nanofluid is implemented in heat pipe.