WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article CFD-DEM Investigation on Particle Separation from Fluid Flow Using Magnetic Fields(Elsevier, 2026) Morsali, Shaghayegh; Kazemi, Saman; Farahani, Farhang Jalali; Zarghami, RezaThis study presents a numerical simulation of magnetic particle separation from fluid flow using CFD-DEM modeling. Studies have shown that magnetic fields are an effective tool for particle separation, especially on small scales, and variables such as magnetic field intensity, fluid velocity, and particle size significantly impact separation efficiency. Other factors, such as the initial location of particles and their density, were also examined, and their effect on the attraction of particles was determined. The magnetic field was applied through a line dipole in the fluid channel. The simulation results show that particles accumulate in the channel area where the line dipole is located, with higher particle concentration at the beginning of the dipole compared to other sections. Additionally, the results indicate that increasing the magnetic field intensity significantly improves separation efficiency, while increasing fluid velocity can decrease this efficiency. At a velocity of 0.2 m per second, results showed that increasing the magnetic field intensity from 0.6 to 3 T improved the capture efficiency from 69 % to 91 %. Similarly, at a magnetic field intensity of 1 T, reducing the fluid velocity from 0.3 to 0.1 m per second doubled the capture efficiency. In the optimal state, combining maximum field intensity with minimum velocity can achieve an efficiency of 98 %. It was also observed that larger particle diameters and higher densities have a positive effect on particle attraction.Article A Novel ORC-PEM Integrated System for Sustainable Hydrogen Production from Low-Grade Waste Heat in Oil Refineries(Elsevier, 2025) Nazerifard, Reza; Mohammadpourfard, Mousa; Zarghami, RezaThis study presents an integrated multi-generation system for sustainable hydrogen production by harnessing low-grade waste heat from the overhead stream of the NHT unit's stripper column in an oil refinery. The proposed system integrates an ORC with a PEM electrolyzer, forming a novel energy solution that efficiently converts waste heat into clean hydrogen through electricity generation. A detailed model of the proposed system is developed, enabling a comprehensive assessment of its performance from thermodynamic, economic, and environmental viewpoints. At the same time, key operational parameters are optimized using the RSM-BBD method to minimize the hydrogen production cost, thereby enhancing the system's economic viability and practical implementation. The results demonstrated that the system achieves a yearly hydrogen production of 304.53 tons under optimized conditions, for 2.36 $/kg. The integrated system's overall energy and exergy efficiencies are calculated at 8.62 % and 33.43 %, respectively, demonstrating its high thermodynamic performance. Additionally, the system mitigates 3047 tons of CO2 annually by displacing conventional hydrogen production methods.Article Reversibility and Entropy in Bubbling Fluidized Beds: A Recurrence-Based Analysis(Elsevier, 2026) Zarghami, Reza; Mohammadpourfard, Mousa; Akkurt, Gulden GokcenNonlinear time series analysis techniques were applied to characterize bubbling fluidization. The delay method was used to reconstruct the state space attractor and analyze the reconstructed state space. The experiments were carried out in a laboratory-scale fluidized bed, operated under ambient conditions and with various sizes of particles, settled bed heights, measurement heights, and superficial gas velocities. The reversibility of the gas-solid fluidized bed hydrodynamics was investigated using pressure fluctuations by recurrence plot analysis. The anti-diagonal lines of the recurrence plot (RP) were regarded as a measure of reversibility. It was shown that the reversibility versus gas velocity has a concave shape in the bubbling regime. The highest reversibility occurs at velocities remarkably lower than the turbulent transition velocity. In addition, reversibility increases as the size of the particles increases. The Kolmogorov entropy was also estimated to confirm the reversibility analysis in the state space domain. In addition, the average cycle frequency and wideband energy in the frequency domain were also used to clarify the results in the state domain. It was found that a minimum in average cycle frequency, wideband energy, and entropy with an increase in the velocity corresponds to the transition between macro-structures and finer structures of the fluidization system. This minimum was primarily found in the macro-structures of the bubbling fluidization system. These findings can provide a practical tool for the optimal design and operation of the fluidized bed.Article Vibration-Assisted Fluidization of Nanocellulose(Elsevier, 2026) Salimi, Sina; Hoorijani, Hamed; Zarghami, Reza; Sotudeh-Gharebagh, Rahmat; Van Geem, Kevin M.Nanocellulose, a renewable nanomaterial prized for its mechanical strength, biocompatibility, and tunable properties, faces challenges in gas-solid fluidization due to nanoparticle agglomeration, weak gas-solid interactions, and high elutriation caused by strong interparticle forces. This study uses pressure fluctuation analysis across frequency and time-frequency (wavelet transform) domains to investigate nanocellulose fluidization in a gas-solid bed. Mechanical vibration was introduced to optimize fluidization, with effects compared against nonvibrated conditions. Results show vibration significantly reduces agglomerate size and enhances bed expansion, improving fluidization efficiency. Notably, vibration lowers the minimum gas velocity requirement by approximately 4-fold. Pressure fluctuation analysis reveals that vibration amplifies low-frequency energy, fostering smaller bubbles and shifting energy contributions from large agglomerates to finer hydrodynamic structures. This shift correlates with intensified agglomerate interactions, leading to breakup and size reduction. Finally, the effect of introducing a powder additive to the nanocellulose bed on the hydrodynamics was examined, showing a moderate rise in macroscale energy at 1 % additive loading and a pronounced shift at 2 %, where macro structures accounted for nearly 45 % of the spectral energy. Overall, these findings underscore vibration-assisted fluidization as a promising method for scalable nanocellulose processing, offering actionable insights for advancing industrial applications.Article Citation - WoS: 4Citation - Scopus: 3Exploration of Electrostatics Effect on Dispersion and Coating Mechanisms in Dry Powder Inhalers by Discrete Element Method(Elsevier, 2025) Saeid, Pooya; Kazemi, Saman; Zarghami, Reza; Sotudeh-Gharebagh, Rahmat; Mostoufi, NavidImproving drug delivery in the respiratory system relies on the effective coating and dispersion of active pharmaceutical ingredients (APIs) in dry powder inhalers (DPIs) and the respiratory system's airways. This study aims to explore the impact of different factors on coating APIs on carrier particles, considering electrostatic and van der Waals forces using the discrete element method (DEM). This study focuses on the critical elements of API dispersion, specifically collisions between API-coated carrier particles with each other and DPI walls. The factors influencing the dispersion ratio in these collisions, such as impact velocity, contact angle, and particle charge, are examined. Additionally, a reduced-scale shaking DPI with three frequencies is used to investigate the API coating mechanism on carriers, which was not explored in previous studies. The difference in work function between carrier particles and APIs generates charge in the shaking DPI due to collisions. This causes electrostatic force to dominate over van der Waals force, breaking agglomerates and attaching APIs to carrier particles. This study shows that the amount of generated charge increases with particle collisions and that charge distribution becomes more balanced over time through charge exchange between particles. By elucidating the relationships among impact velocity, dispersion ratio, shaking frequency, and contact angles, this study paves the way for future research on more efficient DPI designs.