This investigation meticulously examined the thermal transfer capabilities of nanofluids, specifically a suspension of Cu2O3 nanoparticles in a volumetric mixture of 70:30 Propylene Glycol and water, in comparison to the base fluid. The analysis was conducted by modelling the flow dynamics within both laminar and turbulent flow regimes in a flat tube representative of a radiator, utilizing both single-phase and Eulerian-Eulerian multiphase methodologies within computational fluid dynamics (CFD) simulation frameworks. The Nusselt number was determined by varying the Reynolds number across both models, subsequently comparing the results with established theoretical correlations and the empirical data documented in existing literature.