Browsing by Publisher "American Institute of Physics"

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    Nanofluid cooling of a hot rotating circular cylinder employing cross-flow channel cooling on the upper part and multi-jet impingement cooling on the lower part
    (American Institute of Physics, 2024) Selimefendigil F.; Larguech S.; Ghachem K.; Albalawi H.; Alshammari B.M.; Labidi T.; Kolsi L.
    This study explores the convective cooling features of a hot rotating cylinder by using the combined utilization of cross-flow on the upper part and multi-jet impingement on the bottom part. The analysis is performed for a range of jet Reynolds number (Re) values (between 100 and 500), cross-flow Re values (between 100 and 1000), rotational Re values (between −1000 and 1000), cylinder size (between 0.25wj and 3wj in radius), and center placement in the y direction (between −1.5wj and 1.5wj). When the cylinder is not rotating, the average Nu increment becomes 102% at the highest jet Re, while it becomes 140.82% at the highest cross-flow Re. When rations become active, the impacts of cross-flow and jet impingement cooling become slight. As compared to a motionless cylinder, at the highest speed of the rotating cylinder, the average Nu rises by about 357% to 391%. For clockwise rotation of the cylinder, a lager cylinder results an increase in the average Nu by about 86.3%. At the lowest and highest cross-flow impinging jet Re value combinations, cooling performance improvement becomes a factor of 8.1 and 2, respectively. When the size of the cylinder changes, entropy generation becomes significant, while the vertical location of the cylinder has a slight impact on entropy generation. © 2024 Author(s).
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    The physics of phase transition phenomena enhanced by nanoparticles
    (American Institute of Physics, 2025) Yang L.; Tian J.; Ding Y.; Alagumalai A.; Selimefendigil F.; Aghbashlo M.; Tabatabaei M.; Asirvatham L.G.; Wongwises S.; Sherif S.A.; Michaelides E.E.; Markides C.N.; Mahian O.
    Phase transitions are fundamental phenomena in physics that have been extensively studied owing to their applications across diverse industrial sectors, including energy, power, healthcare, and the environment. An example of such applications in the energy sector is thermal energy storage using phase change materials. In such systems, and indeed in many other thermal systems, an emerging and promising approach involves the use of nanoparticles, which have been extensively studied for their potential to enhance the performance of thermal systems. However, conducting thermodynamic analyses of thermal systems in the presence of nanoparticles proves to be complex and resource-consuming because of the involvement of many parameters, including (i) temperature, molecular structure, and composition of the host fluid in which nanoparticles are either dispersed or in physical contact; (ii) nanoparticle morphology, size, type, and concentration; and (iii) complex interactions between the nanoparticles and the base fluid. This article reviews recent studies on the role of nanoparticles in phase transition processes such as freezing, melting, boiling, evaporation, and condensation. It begins with an overview of phase transition phenomena without nanoparticles, emphasizing the most important controlling parameters, and then examines the underlying physics of nanoparticle-involved phase transitions, critically examining their impact on process speed (transport rates). The article also explores physical phenomena, such as Brownian motion, thermophoresis, microconvection, and nanoparticle agglomeration, and considers their contribution to rate control (enhancement or reduction). Finally, the article presents challenges, research gaps, and suggestions for future exploration, aimed at offering a comprehensive understanding of the complex interplay between the presence of nanoparticles and the phase transition processes. © 2024 Author(s).