Nanofluids with Enhanced CHF Prepared from Self-Combustion Synthesized Al₂O₃ Nanoparticles with PEG 1000 as Fuel

To develop a new coolant for nuclear and non-nuclear applications, nanoparticles of Al₂O₃ for nanofluids have been successfully synthesized using a self-combustion method from Al(OH)₃ precursor extracted from local bauxite. A sol was prepared by dissolving the Al(OH)₃ powder in water and adding an amount of PEG 1000 into the solution. The solution was stirred to form a sol and then was heated at 150 °C until forming a gel. The gel was then self-combusted at 450 °C and heated at 600 °C. The combusted and heated material was calcined at 1200 °C for 1 hour to get Al₂O₃ nanoparticles. The preparation of nanofluids was done by dispersing the Al₂O₃ nanoparticles into an amount of water as the base fluid. The Al₂O₃ nanoparticles were crystallized in a theta phase with a crystallite size of 15.7 nm as confirmed by the XRD analyses. According to TEM data, it was known that the particle size of the nanoparticles was 35 nm. The nanofluid with the concentration of 0.025 vol % and pH of 10 possessed zeta potential of -42 mV indicating a stable suspension. This nanofluid had a CHF enhancement of 73% compared to water as the base fluid.