RESUMO
Thermal management is a critical challenge in advanced systems such as electric vehicles (EVs), electronic components, and photoelectric modules. Thermal alleviation is carried out through the cooling systems in which the coolant and the heat exchangers are the key components. The study examines recent literature on nanofluids and heat exchanger tubes along with state-of-the-art concepts being tested for heat transfer intensification. The performance of nanofluids in several common heat transfer tubes' geometries/configurations and the effectiveness of novel heat transfer augmentation mechanisms are presented. Promising results have been reported, showing improved heat transfer parameters with the use of nanofluids and intensification mechanisms like turbulators, fins, grooves, and variations in temperature and flow velocity. These mechanisms enhance dispersion stability, achieve a more uniform temperature distribution, and reduce the boundary layer thickness, resulting in lower tube wall temperatures. Moreover, introducing flow pulsations and magnetic effects further enhances particle mobility and heat exchange. However, there are limitations, such as increased frictional losses and pressure drop due to magnetic effects. The combination of nanofluids, novel heat exchanger tube geometries, and turbulators holds great promise for highly efficient cooling systems in the future. The study also presents a bibliometric analysis that offers valuable insights into the impact and visibility of research in the integration of nanofluids into heat transfer systems. These insights aid in identifying emerging trends and advancing the field towards more efficient and compact systems, paving the way for future advancements.
RESUMO
Although the research on potential use of nanofluids in automotive vehicles is in its embryonic stage, a number of studies have suggested the strong prospect of nanofluids for the efficient thermal management of automotive vehicles. Nevertheless, the pinnacle of nanofluid-based systems awaits stable nanoparticle suspension. The present work studies the heat transfer performance of an aluminum tube automotive radiator with 31 flattened tubes and louvered fins using water and different concentrations (0.04, 0.08, and 0.12 vol.%)-based SiO2/water nanofluids as the engine coolant. Inlet temperature and flowrate of the fluid were varied from 60 to 70 °C and 12 to 18 LPM, respectively. The topmost increment in heat transfer rate of 36.92% and Nusselt number of 45.53% were observed in the upper range of tested operational parameters, however, the relative heat transfer increment percentage dropped from 5% (between 0.04 and 0.08 vol.%) to 3.5% (between 0.08 and 0.12 vol.%) due to agglomeration and cluster formation caused by the presence of a greater number of nanoparticles. Precise evaluation of the experimental results was also carried out by reperforming the tests after three days of initial experimentations. A mere deviation of less than 1% was observed between the initial and repeated tests, however, the decline was caused due to the synergistic effects of clustering and fouling.
