Sensitivity of thermal conductivity for Al2O3 nanofluids

• Phase transition from γ-Al2O3 to α-Al2O3 occurs between 850 and 1150 °C.
• For concentration increase Al2O3-ethylene glycol nanofluids give superior results.
• For temperature increases water based Al2O3 nanofluids shows better performance.
• Thermal conductivity is more sensitive at higher concentration of Al2O3 nanoparticles.
• Ethylene glycol based Al2O3 nanofluids shows higher thermal conductivity sensitivity.

Present work deals with synthesis, characterization and the sensitivity study of thermal conductivity of Al2O3 nanofluids in different base fluids with change in concentration and temperature. In this work, the solution combustion synthesis method was used for synthesis and samples were combusted at three different temperatures. It was observed that increase in combustion temperature leads to the increase in particle size. Al2O3 nanoparticles combusted at 1000 °C, having average particle size 53 nm, were used for preparation of nanofluids in distilled water and ethylene glycol base fluids using two step approach. For change in temperature from 10 to 70 °C and concentration variation from 0 to 2 vol%; 30 and 31% increase in thermal conductivity was observed for distilled water and ethylene glycol based Al2O3 nanofluids, respectively. Finally, sensitivity analysis for thermal conductivity was also performed. Results of sensitivity analysis revealed that change in thermal conductivity is more sensitive to increase in volume percent at higher concentration.