2Department of Mechanical Engineering, BGS College of Engineering and Technology, Bangalore-560086 Karnataka, India; Visvesvaraya Technological University, Belagavi, 560086, India
3Department of Air Conditioning Engineering, College of Engineering, University of Warith Al-Anbiyaa, Karbala, 56001, Iraq
4Department of Mechanical Engineering, Government Engineering College, Karnataka, 562159, India
5Al-Manara College for Medical Sciences, Amarah, 62001, Iraq
6BallarInstitute of Technology and Management, Ballari, 583104, India
7Galgotias College of Engineering, Knowledge Park 11, Greater Noida, 201310, India
8Faculty of Educational Sciences, Al-Ahliyya Amman University, Amman, 19328, Jordan
9Graphic Era (Deemed to be University), Clement Town, Uttarakhand, 248002, India
Abstract
This work is about graphene-TiO₂ hybrid nanofluid used for cooling a diesel engine exhaust manifold via coupled CFD simulations and experimental validation. The authors of this paper confirmed grid independence at more than 800 mesh elements with the pressure converging within -6 to 4 Pa. At 4.102 m/s velocity, the hybrid nanofluid caused a 7.016 Pa pressure drop, whereas the same for the conventional coolants was only 4.620 Pa thereby, the 52% rise in the pressure differential that correlates with the convective mixing enhancement. Streamline visualization depicted flow regularity improvement with the use of nanofluids, whereas turbulent kinetic energy increased steadily from 0.05 to 0.25 m²/s² over the 0-4 m/s velocity range, thereby promoting heat transfer directly. The enhancements in thermal conductivity of 5% and the heat transfer coefficients of 6% (with respect to the baseline fluid) have made it possible to reduce the peak manifold temperature by 340°C. The pressure gradient or the change in pressure remained very stable (within ±6 Pa) all over the domain, which is a clear indication that the hydrodynamic behavior was under control. The experimental data corroborated the CFD predictions with temperature and pressure drop accuracy percentages of 30% and 20%, respectively. These results confirm that graphene-TiO₂ nanofluids are capable of resulting in specific improvement metric of "15% faster heat dissipation" or "20°C lower operating temperatures" in automotive exhaust systems and establish a validated computational framework for nanofluid-based thermal management design in internal combustion engines.
