2026. Enhancing Heat Transfer Efficiency in a Heat Exchanger Using Green-Synthesized Copper Oxide Nanofluids Based on Ethylene Glycol–Water Mixture: Enhancing Heat Transfer Efficiency in a Heat Exchanger. Academic Journal of International University of Erbil. 3, 2 (Apr. 2026), 1054–1070. DOI:https://doi.org/10.63841/iue3261054.