Researchers at the University of Pretoria, led by Emmanuel Oluwaseyi Atofarati as part of his PhD research under the supervision of Prof. Mohsen Sharifpur and Prof. Josua Meyer, have conducted pathfinding research exploring the intricacies of heat transfer enhancement using Al₂O₃-MWCNT/water hybrid nanofluids in jet cooling systems.

This comprehensive study delved into the heat transfer performance of nanofluid-jet impingement cooling (NJIC) systems, focusing on hydrodynamic factors crucial for enhanced efficiency. The research investigated both continuous and pulsating jet impingement cooling conditions, shedding light on the optimal parameters for improved thermal performance.

The study began with a thorough review of previous experimental and numerical studies on NJIC, analyzing the impact of parameters such as target-surface nature, nozzle characteristics, turbulence promoters, and nanofluid properties. This review revealed NJIC's excellent potential for enhanced heat transfer in various applications, including gas turbines, electronic & IC, HVAC systems, solar-thermal collectors, automobiles, and metallurgical processes.

Prospective applications of Nanofluid-Jet impingement Cooling include high energy density electronics, turbine blades, solar thermal systems and electric vehicles.

The synthesis and characterization of an aluminum oxide multiwalled carbon nanotube water (γ-Al₂O₃-MWCNT) hybrid nanofluid highlighted its superior thermal conductivity and viscosity behavior. Key hydrodynamic parameters influencing heat transfer efficiency for continuous and pulsating jet impingement cooling conditions were examined. Notably, the hybrid nanofluid demonstrated a remarkable thermal enhancement of about 21% compared to water under continuous jet impingement. Optimal heat transfer performance was achieved at highest nanofluid volume concentration, a dimensionless jet-to-target gap of 4, a dimensionless jet-diameter of 0.10 and at the highest Reynold number studied.

Further investigations into pulsating jet impingement cooling revealed essential characteristics for efficient heat transfer enhancement, including high duty cycle, low amplitude, low frequency, moderate wave-offset, and sine waveform. The study provided valuable insights into the hydrodynamic behavior and thermal performance of pulsating hybrid nanofluid jet impingement cooling, demonstrating higher cooling rates and contributing to the understanding of this promising cooling technique.

The research outcomes have been disseminated through publications in reputable journals and books, showcasing significant contributions to the field of thermal engineering and nanofluid utilization as listed below. The identified optimized parametric conditions offer practical guidance for enhancing heat transfer performance in various applications, including solar thermal collectors and other thermal absorption and dissipating systems.

Looking ahead, several recommendations have been proposed for future studies in the field of nanofluid-jet impingement cooling. These include investigating the effect of a magnetic field on hybrid nanofluid performance, exploring the combined impact of nanoparticle size and target characteristics, and further studying waveform characteristics for pulsating jet impingement cooling.

In conclusion, this research significantly contributes to the field of heat transfer enhancement using nanofluid-jet impingement cooling. The findings demonstrate the promising potential of hybrid nanofluids as efficient coolants, and the thorough exploration of pulsating jet impingement cooling provides valuable insights for future research and applications. By addressing gaps and limitations in existing literature, this study paves the way for further advancements in NJIC technology, ultimately contributing to energy efficiency and sustainability across industries.

For more information, the journal papers documenting this work are:

1. Pulsating Nanofluid-Jet Impingement Cooling and Its Hydrodynamic Effects on Heat transfer from Solar Thermal Collectors. E. O. Atofarati, M.   Sharifpur, and J. P. Meyer, Int. J. Therm. Sci., vol 198,p.108874, April 2024, https://doi.org/10.1016/j.ijthermalsci.2023.108874
2. Hydrodynamic Effects of Hybrid-Nanofluid Jet on the Heat Transfer Augmentation. E. O. Atofarati, M.   Sharifpur, and J. Meyer, Case Stud. Therm. Eng., vol. 51, p. 103536, Nov. 2023, https://doi.org/10.1016/j.csite.2023.103536  
3. Parametric Factors in Heat Transfer through Nanofluid-Jet Impingement Cooling. E. O. Atofarati, M.   Sharifpur, and J. Meyer, Nanofluids, Preparation, Application and Simulation,  Elsevier, 1st Edition - July 1, 2024, Editor: Mohammad Mehdi Rashidi, Paperback ISBN: 9780443136252, eBook ISBN: 9780443136269.