How “Twisted Tapes” and Nanofluids are redefining the laws of heat transfer

By Rita Okoye

In a world struggling with twin challenges of rising energy needs and the need for carbon neutrality, the pursuit of more energy efficiency has never been more crucial. Our reliance on thermal devices across a spectrum of industries from heating, ventilating, and air conditioning (HVAC) to pharmaceuticals, oil and gas, electronics, and automotive sectors emphazises the urgent need for innovation in thermal engineering. Responding to this global call, a groundbreaking study by Ibrahim Ademola Fetuga, a researcher at University of Lagos, in collaboration with the globally renowned scientist on transitional flow, Josua Petrus Meyer of Stellenbosch University, presents a novel approach to significantly enhance the performance of heat exchangers, the workhorses of thermal systems. His research on “Numerical thermal augmentation of ternary nanofluid in a tube with stent, torus-ring and surface-grooved twisted tapes under non-uniform wall temperature”, offers a pathway to substantial energy savings and a reduced carbon footprint, marking a significant achievement in the field.

At the heart of Fetuga’s research is a sophisticated and multi-faceted strategy to augment heat transfer within a heat exchanger tube. The study introduces a unique combination of cutting-edge techniques, each contributing to a synergistic improvement in thermal performance. The first key innovation is the use of a “ternary nanofluid”—a base fluid of water imbued with a precise mixture of three different nanoparticles: silicon dioxide (SiO₂), zinc oxide (ZnO), and calcium oxide (CaO). These nanoparticles enhance the fluid’s thermal properties, allowing it to absorb and transfer heat more effectively. However, the true ingenuity of this research lies in complex design of the tube’s internal structure. Fetuga has incorporated a trio of inserts: a stent, torus-rings, and, most notably, “surface-grooved twisted tapes.” These are not merely passive components; they are carefully engineered turbulators that create a swirling, chaotic flow within the tube. This induced turbulence disrupts the boundary layer a thin, stagnant layer of fluid that typically impedes heat transfer and promotes a more vigorous mixing of the nanofluid, ensuring a more uniform temperature distribution and a significantly higher rate of heat exchange.

The originality of this work is emphasized by its holistic and realistic approach. While previous studies have explored individual heat transfer enhancement methods, Fetuga’s research is the first to investigate this particular combination of a ternary nanofluid with the innovative stent, torus-ring, and surface-grooved twisted tape configuration. Furthermore, the study distinguishes itself by considering a non-uniform wall temperature, a condition that more accurately reflects the real-world operating environments of heat exchangers. By employing advanced computational fluid dynamics (CFD) simulations, Fetuga managed to strictly model and investigate the complicated interaction between the nanofluid and the complex geometry of the inserts. The results are nothing short of remarkable. The study demonstrates that this distinct configuration can achieve a thermal performance factor up to 2.3 times greater than that of a conventional smooth tube. This translates to a dramatic improvement in heat transfer efficiency, a critical factor in optimizing the performance of thermal systems.

The implications of this research for various industries are insightful and far-reaching. In the manufacturing and processing industries, more efficient heat exchangers can lead to faster heating and cooling cycles, resulting in increased production rates and reduced energy consumption. For the HVAC sector, this technology promises more compact and energy-efficient systems for both residential and commercial buildings, contributing to lower electricity bills and a smaller environmental footprint. In the automotive industry, improved heat exchangers can enhance engine cooling and climate control systems, leading to better fuel economy and reduced emissions. The pharmaceutical and chemical industries, which rely heavily on precise temperature control for their processes, can also benefit from the enhanced thermal management offered by this technology. The potential for energy savings across these sectors is immense, and the adoption of this innovative approach could play an important role in our collective journey towards a more sustainable and energy-efficient future. Ibrahim Fetuga’s work, in collaboration with a distinguished researcher like JP Meyer, not only advances our fundamental understanding of heat transfer but also provides a tangible and practical solution to one of the most pressing challenges of our time. This is evidence of how innovative engineering can be utilized to progress and give a more sustainable world.