@article{YalcınkayaDurmazTepeetal.2024, author = {Yal{\c{c}}{\i}nkaya, Orhan and Durmaz, Ufuk and Tepe, Ahmet {\"U}mit and Benim, Ali Cemal and Uysal, {\"U}nal}, title = {Heat and Flow Characteristics of Aerofoil-Shaped Fins on a Curved Target Surface in a Confined Channel for an Impinging Jet Array}, series = {Energies}, volume = {17}, journal = {Energies}, number = {5}, publisher = {MDPI}, issn = {1996-1073}, doi = {10.3390/en17051238}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-46387}, pages = {21}, year = {2024}, abstract = {The main purpose of this investigation was to explore the heat transfer and flow characteristics of aero-foil-shaped fins combined with extended jet holes, specifically focusing on their feasibility in cooling turbine blades. In this study, a comprehensive investigation was carried out by applying impinging jet array cooling (IJAC) on a semi-circular curved surface, which was roughened using aerofoil-shaped fins. Numerical computations were conducted under three different Reynolds numbers (Re) ranging from 5000 to 25,000, while nozzle-to-target surface spacings (S/d) ranged from 0.5 to 8.0. Furthermore, an assessment was made of the impact of different fin arrangements, single-row (L1), double-row (L2), and triple-row (L3), on convective heat transfer. Detailed examinations were performed on area-averaged and local Nusselt (Nu) numbers, flow properties, and the thermal performance criterion (TPC) on finned and smooth target surfaces. The study's results revealed that the use of aerofoil-shaped fins and the reduction in S/d, along with surface roughening, led to significant increases in the local and area-averaged Nu numbers compared to the conventional IJAC scheme. The most notable heat transfer enhancement was observed at S/d = 0.5 utilizing extended jets and the surface design incorporating aerofoil-shaped fins. Under these specific conditions, the maximum heat transfer enhancement reached 52.81\%. Moreover, the investigation also demonstrated that the highest TPC on the finned surface was achieved when S/d = 2.0 for L2 at Re = 25,000, resulting in a TPC value of 1.12. Furthermore, reducing S/d and mounting aerofoil-shaped fins on the surface yielded a more uniform heat transfer distribution on the relevant surface than IJAC with a smooth surface, ensuring a relatively more uniform heat transfer distribution to minimize the risk of localized overheating.}, subject = {Beschaufelung}, language = {en} } @article{ShajahanBenim2026, author = {Shajahan, Mohamed Iqbal and Benim, Ali Cemal}, title = {Granular PCM based heat sink for electronics thermal management}, series = {Applied Thermal Engineering}, volume = {286}, journal = {Applied Thermal Engineering}, publisher = {Elsevier}, issn = {1359-4311}, doi = {10.1016/j.applthermaleng.2025.129336}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-59649}, year = {2026}, abstract = {This study investigates aluminum heat sinks integrated with GR42 phase change material (PCM), aiming to enhance thermal inertia and stabilize device temperatures. This is important, since the increasing miniaturization and performance demands for electronic devices have led in a growing need for advanced thermal management systems capable of handling rapid transient loads. The novelty of the work lies in examining different heat sink layouts that optimize the heat dissipation capabilities of GR42 PCMs while minimizing size and weight for electronic cooling. The experimental testing was conducted using three configurations, namely no fin, circular fin and hexagonal fin, with three input powers (4 W, 8 W, and 12 W). The experimental results show that the hexagonal-fin heat sink, surface area is 25 \% more than circular fins, exhibited superior thermal performance without significant variation in input power. Notably, the hexagonal-fin heat sink achieved the desired set point temperature of 55 ◦C in 33 \% less time than the circular-fin design and 45 \% less time than the heat sink without fins. Furthermore, the peak temperatures increased up to 21 \% for circular fins. During the charging cycles, the enhancement ratios vary from 72 \% and begin to narrow to 25 \% during discharge cycles. The hexagonal-fin configuration also exhibited superior melting dynamics, completing the phase transition 44 \% faster at higher input power than the circular fins, and established a thermal deviation of nearly 51 \% less than finless heat sinks. These findings underscore the critical role of fin geometry and PCM integration in achieving uniform temperature distribution and improved energy storage efficiency. Overall, the hexagonal-fin heat sink with GR42 PCM shows strong potential as a passive cooling solution for low-power portable electronic devices.}, language = {en} } @article{RueckertIbrarAhmedetal.2024, author = {R{\"u}ckert, Frank Ulrich and Ibrar, Burhan and Ahmed, Arslan and Allweyer, Benjamin and H{\"u}bner, Dirk and Klinger, Friedrich and Knaus, Hermann and Benim, Ali Cemal}, title = {Fluid flow and heat transfer of a novel passive cooling system for gearless wind turbines with a power range of 3-12 MW}, series = {Energy}, volume = {312}, journal = {Energy}, publisher = {Elsevier}, issn = {0360-5442}, doi = {10.1016/j.energy.2024.133478}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-46594}, year = {2024}, abstract = {Today, the gearless horizontal axis wind turbines are mainstream in wind energy industry. High demands of electric power led to bigger systems and active cooling reduces the overall efficiency of the turbines. Passive cooling systems have been examined for the first time for a gearless wind energy generator with power range of 3-12 MW. With further developed heat conductors, it is possible to operate a wind generator in a larger power class with passive cooling components. This is accompanied by enormous cost savings due to elimination of costs for active cooling elements such as the use of fans, pumps, and heat exchangers. An additional factor is the significant reduction in necessary maintenance due to the minimized incidence of corrosion and wear. Design of the cooling fins and an ideal position of the generator within the housing of the wind turbine has been objectives. Mandatory is that maximum temperatures of the generator fins should stay under 155 °C, which could be reached with several designs for different heat exchanger geometries.}, subject = {Windturbine}, language = {en} } @article{Benim1989, author = {Benim, Ali Cemal}, title = {Finite element solution of an enclosed turbulent diffusion flame}, series = {International Journal for Numerical Methods in Fluids}, volume = {9}, journal = {International Journal for Numerical Methods in Fluids}, number = {3}, publisher = {Wiley}, issn = {0271-2091}, doi = {10.1002/fld.1650090305}, pages = {289 -- 303}, year = {1989}, abstract = {A finite element formulation of enclosed turbulent diffusion flames is presented. A primitive variables approach is preferred in the analysis. A mixed interpolation is employed for the velocity and pressure. In the solution of the Navier-Stokes equations, a segregated formulation is adopted, where the pressure discretization equation is obtained directly from the discretized continuity equation, considering the velocity-pressure relationships in the discretized momentum equations. The state of turbulence is defined by a κ-ϵ model. Near solid boundaries, a wall function approach is employed. The combustion rates are estimated using the eddy dissipation concept. The expensive direct treatment of the integrodifferential equations of radiation is avoided by employing the moment method, which allows the derivation of an approximate local field equation for the radiation intensity. The proposed finite element model is verified by investigating a technical turbulent diffusion flame of semi-industrial size, and comparing the results with experiments and finite difference predictions.}, subject = {Finite-Elemente-Methode}, language = {en} } @article{Benim1990, author = {Benim, Ali Cemal}, title = {Finite element analysis of confined turbulent swirling flows}, series = {International Journal for Numerical Methods in Fluids}, volume = {11}, journal = {International Journal for Numerical Methods in Fluids}, number = {6}, publisher = {Wiley}, issn = {0271-2091}, doi = {10.1002/fld.1650110602}, pages = {697 -- 717}, year = {1990}, abstract = {The finite element method is applied to incompressible and statistically steady confined turbulent swirling flows. A velocity-pressure formulation is employed. The momentum and continuity equations are solved using a segregated algorithm. Two turbulence models, namely the standard κ-ε model and the algebraic stress model, are considered. It is shown that the algebraic stress model leads to significantly more accurate results in swirling flows compared to the κ-ε model. A novel way of implementing the algebraic stress model is presented in which the stresses are coupled to the Navier-Stokes equations in such a way that they 'correct' the effective viscosity hypothesis. This formulation seems to provide a convenient approach for finite elements. In deriving the discretization equations, a streamline-upwind/Petrov-Galerkin method is employed. Comparisons performed between various upwind schemes show that the numerical solution may be substantially affected by the particular upwind procedure used. The analysis is extended to the prediction of particle motion in turbulent swirling flow fields. Here the fluid turbulence is modelled adopting a stochastic approach. The influence of turbulence modelling on particle movement is investigated.}, subject = {Finite-Elemente-Methode}, language = {en} } @article{BiswasMandalBoseetal.2023, author = {Biswas, Nirmalendu and Mandal, Dipak Kumar and Bose, Sharmistha and Manna, Nirmal K. and Benim, Ali Cemal}, title = {Experimental Treatment of Solar Chimney Power Plant — A Comprehensive Review}, series = {Energies}, volume = {16}, journal = {Energies}, number = {17}, publisher = {MDPI}, issn = {1996-1073}, doi = {10.3390/en16176134}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-46139}, pages = {41}, year = {2023}, abstract = {Solar chimney power plants (SCPPs) are encouraging sustainable energy sources due to their low cost, abundance, low maintenance, and eco-friendliness. However, despite significant efforts to optimize SCPP design, their efficiency and power generation capabilities remain limited. Researchers have explored modifications in plant geometry and hybridization to improve efficiency. Despite extensive work in this area, commercialization of SCPPs has not yet been achieved. Most of the research is numerical and may differ from real-world practical use. The number of experimental studies is also relatively small. To facilitate commercialization, further investigation with practical and feasible dimensions is required. This comprehensive review paper aims to provide an in-depth analysis of experimental approaches and advancements in the field of SCPPs. The paper begins with an introduction, highlighting the background, significance, and objectives of the review. It provides an overview of the plants, discussing their principles and operation as innovative renewable energy systems. The historical development and evolution of solar chimneys are explored, shedding light on their progression over time. Case studies of operational hybrid SCPPs are examined to showcase real-world applications and performance. The paper also addresses environmental impacts and sustainability considerations associated with SCPPs. Furthermore, recommendations for future research and development in this field are provided to guide researchers and industry professionals. This study focuses on the possibility of commercialization of both standalone and hybrid SCPPs.}, subject = {Erneuerbare Energien}, language = {en} } @article{BhattacharyyaBenimChattopadhyayetal.2019, author = {Bhattacharyya, Suvanjan and Benim, Ali Cemal and Chattopadhyay, Himadri and Banerjee, Arnab}, title = {Experimental investigation of heat transfer performance of corrugated tube with spring tape inserts}, series = {Experimental Heat Transfer}, volume = {32}, journal = {Experimental Heat Transfer}, number = {5}, publisher = {Taylor \& Francis}, issn = {0891-6152}, doi = {10.1080/08916152.2018.1531955}, pages = {411 -- 425}, year = {2019}, language = {en} } @article{SulaimanSaberHasanetal.2025, author = {Sulaiman, Mohammed A. and Saber, Hindren Ali and Hasan, Hasan F. and Benim, Ali Cemal}, title = {Experimental and numerical investigation of novel dew-point evaporative cooler with shell and tube design}, series = {Energy}, volume = {317}, journal = {Energy}, publisher = {Elsevier}, issn = {0360-5442}, doi = {10.1016/j.energy.2025.134686}, year = {2025}, subject = {Numerische Str{\"o}mungssimulation}, language = {en} } @unpublished{SulaimanSaberHasanetal.2024, author = {Sulaiman, Mohammed Abdulqader and Saber, Hindren Ali and Hasan, Hasan Fahmi and Benim, Ali Cemal}, title = {Experimental and Numerical Investigation of Novel Dew-Point Evaporative Cooler with Shell and Tube Design}, series = {SSRN}, journal = {SSRN}, publisher = {Elsevier}, doi = {10.2139/ssrn.4980477}, pages = {38}, year = {2024}, abstract = {Implementing a neoteric practical design for dew-point evaporative cooler (DPEC) rather than the widely utilized flat plate and corrugated plate has been challenging since the first invention. Thus far, no study has been dedicated to design and experimentally implement a shell and tube concept for DPEC with an innovative configuration that can contribute in mass production, globalization, and effortless maintenance of such a high performance cooling machine. Therefore, in this paper, the shell and tube concept has been employed as a core design for DPEC that has been reinforced by a practical approaches. The practical approaches include a dedicated novel design for the proposed system and utilizing super cheap materials for the system's construction. Both of the aforementioned approaches provide solutions for overcoming the aforementioned issues. In the meanwhile, the superiority of the proposed DPEC has been approved by comparing it to the flat plate DPEC. During the experimentations, the prototype was able to reduce the ambient temperature by up to 34.1°C (from 53°C to 18.9°C), besides, it could achieve a dew-point effectiveness of 99.6\% and wet-bulb effectiveness of 135\%.}, subject = {Numerische Str{\"o}mungssimulation}, language = {en} } @article{BenimEscudierNahavandietal.2010, author = {Benim, Ali Cemal and Escudier, Marcel and Nahavandi, Ali and Nickson, A. K. and Syed, Khawar J. and Joos, Franz}, title = {Experimental and numerical investigation of isothermal flow in an idealized swirl combustor}, series = {International Journal of Numerical Methods for Heat \& Fluid Flow}, volume = {20}, journal = {International Journal of Numerical Methods for Heat \& Fluid Flow}, number = {3}, publisher = {Emerald}, doi = {10.1108/09615531011024084}, pages = {348 -- 370}, year = {2010}, language = {en} }