Article
Mathematics
Lioua Kolsi, Fatih Selimefendigil, Lotfi Ben Said, Abdelhakim Mesloub, Faisal Alresheedi
Summary: The study analyzed the forced convection of non-Newtonian nanofluid in a backward-facing flow system under the influence of a magnetic field and double rotating cylinders, showing significant effects on convective heat transfer and flow features. The presence of rotating double cylinders created a complex flow field with multiple recirculation regions, while the magnetic field helped suppress large vortices behind the step. The direction of rotation of the cylinders and the strength of the magnetic field had varying impacts on heat transfer enhancement and flow behavior.
Article
Thermodynamics
Saad Inam, Marcello Lappa
Summary: This study numerically investigates the unsteady mixed forced-buoyancy convection in a channel with a backward facing step. By setting some portions of the boundary as isothermal or adiabatic surfaces, the interplay of forced and buoyancy convection under different conditions is explored. The results reveal a variety of mechanisms involved in this interaction, ranging from standard hydrodynamic phenomena to buoyant effects.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Ayad S. Abedalh, Zaid A. Shaalan, Husam Naufal Saleh Yassien
Summary: The experimental study on convective heat transfer flow of hybrid nanofluids over a backward facing step in a heated rectangular duct under laminar flow showed significant enhancement in heat transfer and pressure drop using a mixture of Al2O3 and TiO2 solid nanoparticles in pure water. The results indicated that the Nusselt number increases with higher Reynolds number and mass fraction, while the friction factor decreases under these conditions. Enhancements of heat transfer and pressure drop were approximately 14% and 4% respectively.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Fatih Selimefendigil, Hakan F. Oztop
Summary: The study examines the convective heat transfer and fluid flow over a facing step in the presence of a porous object downstream, using numerical analysis and optimization. The research observes significant effects on fluid flow and heat transfer rate improvement due to variations in the obstacle's characteristics and location.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Engineering, Multidisciplinary
Mohamad Klazly, Gabriella Bognar
Summary: This study numerically investigates laminar flow in a micro-sized backward-facing step channel for water-based nanofluids. The impact of temperature differences between the inlet and the downward wall temperatures is also studied. The results show that increasing the concentration of nanoparticles can enhance the velocity and shear stress, as well as improve the heat transfer rate. However, a high volume fraction of nanoparticles decreases the performance efficiency.
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Engineering, Chemical
Peymaneh Dehghan, Fatemeh Keramat, Masoud Mofarahi, Chang-Ha Lee
Summary: This study investigates the effects of an inclined step combined with different types of obstacles on the heat transfer of graphene oxide nanofluid inside a double backward-facing microchannel. The simulation results show that placing a triangular obstacle at the top of the first step significantly increases the Nusselt number and heat transfer coefficient compared to pure water. High pressure drop improves heat transfer, and the friction factor is influenced by the presence and location of triangular obstacles.
JOURNAL OF THE TAIWAN INSTITUTE OF CHEMICAL ENGINEERS
(2023)
Article
Engineering, Multidisciplinary
Rumman Hossain, A. K. Azad, Md Jahid Hasan, M. M. Rahman
Summary: This study conducted a numerical analysis of thermal radiation in a square enclosure with a semicircular heater and a sliding lid. The results showed that increasing radiation intensity and dimensionless time improves fluid velocity, pressure gradient, and temperature gradient, but decreases the heat transfer rate of the semicircular heater.
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Thermodynamics
Duna T. Yaseen, Amani J. Majeed, Muneer A. Ismael
Summary: This paper investigates the mixed convection heat transfer and fluid-structure interaction (FSI) of a hot cylinder placed in a backward-step channel. The influence of different configurations of a flexible step on cooling performance was evaluated. Results showed that adjusting the flexibility of the step can improve heat transfer performance and fluid dynamics at low Reynolds number.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2022)
Article
Thermodynamics
Saboura Yousefi, Mostafa Mahdavi, Seyed Soheil Mousavi Ajarostaghi, Mohsen Sharifpur
Summary: Due to rapid development in technology and improved performance of materials, thermal management is important. In this study, the application of nanofluid in a microchannel heat sink with ribs and dimples is numerically investigated. The results show that increasing the number and height of ribs leads to significant improvements in heat transfer.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2023)
Article
Thermodynamics
Tran Dinh Manh, A. M. Abazari, M. Barzegar Gerdroodbary, Nguyen Dang Nam, R. Moradi, Houman Babazadeh
Summary: This study uses the Finite Volume Method to simulate the thermal performance of nanofluids under non-uniform magnetic fields, finding that the addition of magnetic sources can significantly increase local heat transfer.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Thermodynamics
Saurav Kumar, Manash Protim Boruah, Sukumar Pati
Summary: The hydrothermal performance of viscoplastic fluid flowing through a backward facing step channel is studied. The Bingham number, Reynolds number, and power law index are analyzed for their effects on thermal and flow characteristics. Results show that an increase in Bingham number leads to a decrease in reattachment length and an increase in temperature drop. The local Nusselt number peaks near the step and increases with Bingham number.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Multidisciplinary Sciences
K. Padmaja, Rushi B. Kumar
Summary: This paper numerically evaluates the flow of nanofluids through a vertical plate in a porous medium. The study takes into account Dufour and Soret impacts coupled with higher order chemical reactions and investigates heat and mass transfer. The flow equations are transformed from partial differential equations to ordinary differential equations using similarity transformation variables, and the Runge-Kutta method and shooting technique are employed to solve the converted system. The impact of different chemical reaction orders on flow properties is analyzed using MATLAB.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Physical
B. Pekmen Geridonmez, Hakan F. Oztop
Summary: This paper numerically studies the mixed convection flow of hybrid nanofluid in a backward facing step channel with a uniform partial magnetic field, considering different inlet velocity profiles. The results show that the smallest convective heat transfer occurs in the step-centered partial magnetic field, and an increase in magnetite nanoparticles significantly affects convective heat transfer.
Article
Engineering, Multidisciplinary
Rumman Hossain, A. K. Azad, Md Jahid Hasan, M. M. Rahman
Summary: This study numerically explores the time-dependent thermophysical characteristics of multiwalet carbon nanotubes in kerosene oil-based nanofluids, considering different concentrations. The results demonstrate that particle concentration significantly improves the thermophysical properties and heat transfer rate of the nanofluids.
ENGINEERING SCIENCE AND TECHNOLOGY-AN INTERNATIONAL JOURNAL-JESTECH
(2022)
Article
Thermodynamics
Xingyu Ma, Zhanqi Tang, Nan Jiang
Summary: This study investigates spanwise coherent structures in the turbulent shear layer downstream of a two-dimensional backward-facing step. The research reveals that these coherent structures have a significant influence on the convection velocities of the coherent structures in the latter half of the shear layer.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2022)
Article
Energy & Fuels
Amin Shahsavar, Majid Jafari, Ighball Baniasad Askari, Fatih Selimefendigil
Summary: In this study, the influence of the number of ribs on the laminar forced convection flow of a silver/water-ethylene glycol nano-fluid in a rifled tube was investigated using the two-phase mixture model. The results showed that increasing the number of ribs was beneficial from the perspective of the first-law performance, but undesirable from the perspective of the second-law performance. It was also found that the rifled tube consistently outperformed the plain tube in terms of hydrothermal performance.
ENERGY SOURCES PART A-RECOVERY UTILIZATION AND ENVIRONMENTAL EFFECTS
(2023)
Article
Energy & Fuels
Fatih Selimefendigil, Ceylin Sirin
Summary: In this study, three different PVT-air collectors were designed and manufactured, and their performances were compared through experiments. The results showed that utilizing a nano-enhanced thermal energy storage system and increasing flow rate significantly improved both the electrical and thermal performances of the PVT system.
JOURNAL OF ENERGY STORAGE
(2022)
Article
Thermodynamics
Fatih Selimefendigil, Hakan F. Oztop
Summary: The thermal performance features of a coupled conjugate thermo-fluid system with different cooling configurations were explored using non-Newtonian nanofluid. Different system parameters, such as Reynolds numbers, power-law index, height, corrugation number, and jet distance, were studied to understand their effects on the thermal performance. The use of different nanoparticles and fluid parameters in various configurations resulted in different impacts on the thermal performance.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Engineering, Multidisciplinary
Kaouther Ghachem, Fatih Selimefendigil, Hakan F. Oztop, Muapper Alhadri, Lioua Kolsi, Naif Alshammari
Summary: This study investigates the phase change dynamics of hybrid nanofluid in a phase change packed bed with rotational surface effects, area expansion, and nanoparticle loading. Results show that higher rotational Reynolds number and nanoparticle concentration accelerate the phase change process, while the effects become reverse in the presence of rotations.
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Green & Sustainable Science & Technology
Ceylin Sirin, Fatih Selimefendigil, Hakan Fehmi Oztop
Summary: In this study, thermal energy storage unit-integrated photovoltaic thermal (PVT) air collectors with and without nanoparticles were designed, fabricated, and tested. The integration of aluminum oxide nanoparticles into the thermal storage unit improved the performance of the PVT collector, reducing drying time by approximately 15-22%. The use of nanoparticles in the thermal energy storage unit also improved the overall energy and exergy efficiencies of the PVT air collectors, with an increase of 6.91-6.97% and 9.20-9.47%, respectively. The combination of increasing the flow rate and integrating nanoparticles into the storage unit further improved the overall exergetic efficiency of the PVT air collector by 28.58%.
Review
Multidisciplinary Sciences
Fatih Selimefendigil, Gurel Senol, Hakan F. Oztop, Nidal H. Abu-Hamdeh
Summary: This review discusses the applications of non-Newtonian nanofluids for convection in cavities under a magnetic field. Convection in cavities is of great significance in thermal energy systems, with various applications in different processes. The review provides information on nanofluids and non-Newtonian fluids, and focuses on the thermal conductivity/viscosity, as well as the magnetohydrodynamic effects of non-Newtonian nanofluids. Different applications of vented cavities using nanofluid and magnetic field are explored. The review points out the gaps in current literature and discusses future trends.
Article
Multidisciplinary Sciences
Hakan F. Oztop, Omer Akbal, Fatih Selimefendigil, Nidal H. Abu-Hamdeh
Summary: Three-dimensional computational analysis investigates the melting time of PCM in a sinusoidal pipe inserted into another pipe. The study aims to control melting time through passive techniques by adjusting the geometrical parameter without extra energy consumption.
Article
Energy & Fuels
Fatih Selimefendigil, Furkan Dilbaz, Hakan F. Oztop
Summary: The thermal management of lithium-ion batteries is crucial for improving their performance and lifespan. This study proposes a novel cooling system using an inner cylinder and different-shaped nanoparticles as the cooling medium. Numerical analysis shows that both cooling media reduce the highest temperature and homogenize the temperatures in the battery as the Reynolds number increases. The utilization of a nanofluid containing cylindrical-shaped nanoparticles and a cylinder in the mini-channel proves to be an effective cooling system for battery thermal management.
Article
Thermodynamics
Fatih Selimefendigil, Hakan F. oeztop
Summary: The design of a cooling system for a curved conductive panel is developed using nano-enhanced multiple jet impingement. The study shows that the type of panel and operating parameters affect cooling performance and entropy generation. Adjustments in operating parameters can improve cooling effectiveness and reduce entropy generation.
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2023)
Article
Thermodynamics
Hakan F. Oztop, Fatih Selimefendigil, Hakan Cosanay, Nidal Abu-Hamdeh
Summary: In this study, the phase change process and convection inside an open cavity equipped with two different phase change materials (PCMs) were analyzed using the finite volume method with ANSYS Fluent. The analysis was conducted for different Grashof number values and it was found that the PC becomes faster when the object is closer to the exit in the fully open case. The partly open case results in higher thermal performance improvements, with a 94.5% increase in the average Nusselt number for PCM-18.
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2023)
Article
Green & Sustainable Science & Technology
Fatih Selimefendigil, Damla Okulu, Hakan F. Öztop
Summary: Two different cooling systems were developed for the thermal management of a photovoltaic module. The PV/TEG and PV/TEG-mini-channel cooling systems used water and Al2O3 nanofluids in the cooling channel. Higher-loading nanoparticles in the base fluid achieved effective cooling, and the nanofluid showed non-Newtonian behavior. The PV/TEG-cooling channel with the lowest fluid inlet temperature and the highest particle loading resulted in significantly increased PV efficiency and TEG output power compared to PV/TEG and conventional PV systems without cooling.
Article
Energy & Fuels
Hakan F. F. Oztop, Elanur Baki Sezgin
Summary: The use of containers with streamlined corners reduces the melting time of phase change materials (PCMs) under the same boundary conditions, serving as a passive control method to improve energy efficiency.
ENERGY SOURCES PART A-RECOVERY UTILIZATION AND ENVIRONMENTAL EFFECTS
(2023)
Article
Thermodynamics
Burak Kiyak, Hakan F. Oztop, I. Gokhan Aksoy
Summary: This study investigated the melting performance of phase change materials in a disk-shaped container with partial circular heating. The results showed that in partial heating cases, increasing the aspect ratio extended the melting time and decreased the liquid fraction.
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2023)
Article
Thermodynamics
Sudhanshu Kumar, Krunal M. Gangawane, Hakan F. Oztop, Sibasish Panda
Summary: This research work presents a numerical investigation of magnetohydrodynamics (MHD) characteristics near-wall blockage due to double-diffusive convection (DDC) in a rectangular cavity. The results show that as the separation distance increases, heat and mass transfer rates enhance, while the increase in Hartmann number (Ha) results in a monotonic decrease in heat and mass transfer rates.
NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
(2023)
Article
Energy & Fuels
Fatih Selimefendigil, Hakan F. Oztop
Summary: The study numerically assessed the effects of using phase change material (PCM) and non-Newtonian power law (PL) fluid in a double pipe heat exchanger, finding that PCM significantly reduced phase transition time and exploring variations in thermal performance under different conditions.
Article
Engineering, Chemical
Yongxiang Wu, Nguyen Thi Hong Nhung, Deqian Zeng, Nengneng Luo, Akira Otsuki, Gjergj Dodbiba, Toyohisa Fujita
Summary: This study proposed a novel method for synthesizing flower-like vaterite calcium carbonate using nanobubble-containing ethanol and water mixed solution as the solvent and discussed the formation mechanism of vaterite with different shapes. The synthesized vaterite has significant practical interest in the integrated treatment of wastewater contaminated by heavy metals with effective Cd(II) removal, providing a promising field for studying heavy metal and pollutant adsorption in the liquid phase.
ADVANCED POWDER TECHNOLOGY
(2024)
Article
Engineering, Chemical
Jian Gong, Lipo Cheng, Ming Liu, Jie Jiang, Xiaoduo Ou
Summary: This study investigates the effects of particle shape on the collapse of granular columns using the discrete element method. The results show that particle shape has a significant impact on deposition morphology, energy evolution, and mechanical coordination number. Sphericity and angularity are identified as the most important macroscale factors, while roughness has a weaker microscale influence.
ADVANCED POWDER TECHNOLOGY
(2024)
