Analysis on thermal conductivity of green processed alumina nanofluid for thermal industries

Abstract

The dual mechanism played by curry leaf extract on synthesis of alumina nanoparticles contributes a significant enhancement in thermal conductivity of alumina nanofluid with appreciably small volume fraction from 0.01%–0.05%. The most probable particle size of alumina nanoparticle dispersed in water of 3.12 nm observed from particle size analyser along with a strong absorption peak at λ max around 238 nm confirms the alumina nanoparticles in the fluid. The increase of energy band gap from 4.8 to 5.12 eV indicates the decrease in size of the nanoparticle solely attributed to contribution of curry leaf extraction method of preparation of nanoparticles. The spherical shaped alumina nanoparticle has got high thermal conductivity with enhancement from 1.8% to 21.44% which is attributed to the significant contribution of H-atom as energy storage unit in water. With increase of sonication time, thermal conductivity varies appreciably from 0.531 W mK−1 to 0.736 W mK−1 with volume fraction of nanofluid. Therefore, the novel combinations of characterised properties of Al2O3 nanofluid have proved to be the best thermally stable heat transfer fluid compared to conventional cooling fluids.