Experimental and theoretical study to improve heat transfer using nanofluids flow in copper tube

Improving heat transfer efficiency in base fluids remains a key challenge in various thermal applications. To address this, several researchers have suggested the integration of nanoparticles into base fluids, leveraging recent advancements in nanotechnology to enhance performance. This study compares different types of nanoparticles and preparation methods for nanofluids and examines the impact of their properties on improving heat transfer. The convective heat transfer under a turbulent flow regime was studied experimentally and numerically in a copper tube used as a test section. Advanced measurement techniques were employed, including a Flux Teq LLC heat flux sensor mounted on the test section wall's inner surface to measure the instantaneous heat flux and inner surface temperature. Additionally, five T-type thermocouples were used to measure the bulk temperature. Three types of nanoparticles—titanium dioxide, copper oxide, and graphene nanoplates were used at three different concentrations (0.01, 0.02, and 0.03 vol. %) to prepare the nanofluids. The results of applying these nanofluids in the heat transfer process showed that the heat transfer coefficient increased with the concentration of nanoparticles. The greatest improvement was observed at a concentration of 0.03%, with heat transfer coefficient increases compared to the base fluid of 23.7%, 39.1%, and 68.25% for TiO₂, CuO, and GNP, respectively. Numerical results were obtained using COMSOL 5.6, a computational fluid dynamics (CFD) analytical program. The predicted and experimental values were compared to validate the model, showing good agreement between the results, though minor differences were observed. These findings highlight the potential of nanofluids as an innovative solution for advanced heat transfer applications, offering enhanced performance and energy savings.