Enhancing Heat Transfer Efficiency in a Heat Exchanger Using Green-Synthesized Copper Oxide Nanofluids Based on Ethylene Glycol–Water Mixture

The efficiency of industrial heat exchangers is limited by the heat transfer coefficient when using traditional fluids. This study introduces a novel sustainable approach for synthesizing copper oxide nanoparticles (CuO NPs), utilizing an eco-friendly route with Populus Euphratica leaf extract, a method has never reported before. This work represents the first reported application of green-synthesized CuO nanoparticles in a heat exchanger, marking a novel contribution to sustainable thermal management. The synthesis was optimized at pH of 7, 9, and 11. FTIR, XRD, UV-Vis spectroscopy, and SEM analyses were employed to characterize the CuO NPs to confirm their chemical composition, crystallinity, and morphology. The optimized CuO NPs were dispersed into a different ratio of the base fluid of EG-W at different concentration of CuO NPs ranging from 0.02 % to 0.1 % for enhancing thermal performance. The findings showed that, relative to the base fluid, the overall heat transfer coefficient improved by 40% while the convective heat transfer coefficient in terms of nanofluid increased by about 36 %. The rise in convective heat transfer is attributed not only to the static presence of the nanoparticles but also to Brownian motion and the formation of a liquid nanolayer around the particles. A consistent rise in thermal conductivity as well as the Nusselt number is consistently observed with increasing nanoparticle concentration. These findings confirm the thermal performance benefits of green-synthesized CuO nanofluids and support their potential for industrial heat exchanger applications. Conclusively, the study highlights the viability of green nanotechnology as an environmentally responsible alternative to conventional synthesis for energy-efficient thermal management systems.