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- MakaleAçık Erişim2026Scopus SJRQ1Multi-parameter hydrodynamic analysis of pulsation frequency and waveform effects in a conical spouted bed: A CFD study
Çutay, Arif; Tozlu, Alperen; Kütük, Begüm; Özahi, Emrah
The hydrodynamic behavior of spouted beds is strongly influenced by inlet flow conditions, particularly under pulsating operation. In this study, a three-dimensional Eulerian–Eulerian two-fluid model coupled with the kinetic theory of granular flow was used to investigate the effects of pulsation frequency and waveform on the hydrodynamics of a conical spouted bed. Steady, sinusoidal, pulsatile, and square-wave inlet conditions were analyzed at 1, 3, 5, and 10 Hz. A multi-parameter evaluation framework was applied by combining spout height, temporal stability, axial gas and particle velocity distributions, and mixing characteristics. Spout height was determined using the connected αs=0.05 iso-contour, while temporal behavior was quantified through the mean spout height, standard deviation, coefficient of fluctuation, and fluctuation range. The results show that spout performance depends not only on instantaneous inlet velocity but also on the persistence of axial momentum transfer. Although the steady condition and some high-penetration pulsating cases produced relatively large instantaneous spout heights, they did not necessarily provide the most favorable hydrodynamic behavior because of rapid velocity decay, stronger fluctuations, or reduced structural coherence. Pulsation at 3 Hz provided the best overall balance by sustaining particle transport and improving temporal stability. The 5 Hz cases enhanced mixing but exhibited larger fluctuations, whereas the 10 Hz cases produced weaker and less coherent spout structures because of rapid attenuation of the imposed oscillations. Overall, the proposed framework demonstrates that spouting performance should be evaluated through the combined effects of penetration, stability, momentum persistence, and mixing.
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İncele - Kitap BölümüYalnız künye2025CFD and solar water collector
Guclu, Tamer; Cuce, Pinar Mert; Cuce, Erdem
Increasing environmental pollution on a global scale and the rapid depletion of traditional energy sources have led scientists to search for clean and renewable energy sources. Among renewable energy sources, solar energy stands out as a clean, energy-efficient and abundant source. There are many methods of obtaining thermal and electrical energy from solar energy. Among these methods, solar water collectors are widely used throughout the world, thanks to their wide range of applications, from domestic hot water supply and space heating applications to industrial process heat. The main purpose of this study is to examine solar water collector systems in a general framework. Solar water collector types are introduced in detail, their performance is evaluated, and especially CFD studies on their thermal efficiency are presented. Solar water collector systems were examined comparatively in terms of energy efficiency and the parameters affecting their thermal performance were observed. As a general acceptance, evacuated-tube solar water collectors are more efficient than flat-plate collectors. Compound parabolic collectors are preferred in higher-temperature applications. Thermal efficiency can be increased by using nanofluids or hybrid systems.