@article{BiedermannCzeckayHintzenetal.2020, author = {Biedermann, Till M. and Czeckay, Pasquale and Hintzen, Nils and Kameier, Frank and Paschereit, C. O.}, title = {Applicability of Aeroacoustic Scaling Laws of Leading Edge Serrations for Rotating Applications}, series = {acoustics}, volume = {2}, journal = {acoustics}, number = {3}, publisher = {MDPI}, issn = {2624-599X}, doi = {10.3390/acoustics2030030}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-40311}, pages = {579 -- 594}, year = {2020}, language = {en} } @article{MabroukNajiBenimetal.2022, author = {Mabrouk, Riheb and Naji, Hassane and Benim, Ali Cemal and Dhahri, Hacen}, title = {A State of the Art Review on Sensible and Latent Heat Thermal Energy Storage Processes in Porous Media: Mesoscopic Simulation}, series = {Applied Sciences}, volume = {12}, journal = {Applied Sciences}, number = {14}, publisher = {MDPI}, doi = {10.3390/app12146995}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-40343}, year = {2022}, language = {en} } @article{BiswasMandalMannaetal.2022, author = {Biswas, Nirmalendu and Mandal, Dipak Kumar and Manna, Nirmal K. and Benim, Ali Cemal}, title = {Magneto-hydrothermal triple-convection in a W-shaped porous cavity containing oxytactic bacteria}, series = {scientific reports}, volume = {12}, journal = {scientific reports}, publisher = {Springer Nature}, issn = {2045-2322}, doi = {10.1038/s41598-022-18401-7}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-40041}, year = {2022}, abstract = {Bioconvective heat and mass transport phenomena have recently been the subject of interest in diverse fields of applications pertaining to the motion of fluids and their thermophysical properties. The transport processes in a system involving triple convective phenomena, irregular geometry, and boundary conditions constitute a complex phenomenon. This work aims to explore the mixed thermo-bioconvection of magnetically susceptible fluid containing copper nanoparticles and oxytactic bacteria in a novel W-shaped porous cavity. The buoyant convention is generated due to the isothermal heating at the wavy bottom wall, whereas the mixed convection is induced due to the shearing motion of the top-cooled sliding wall. Furthermore, the bioconvection is induced due to the manifestation of oxytactic bacteria or organisms. The inclined sidewalls are insulated. The geometry is packed with water based Cu nanoparticle mixed porous structure, which is subjected to a magnetizing field acted horizontally. The complex transport equations are transformed into nondimensional forms, which are then computed using the finite volume-based developed code. The coupled triple-convective flow physics are explored for a wide range of involved controlling parameters, which could provide helpful insight to the system designer for its proper operation. The shape of geometry can be considered one of the important parameters to control the heat and mass transport phenomena. In general, the influence of amplitude (δ) is more compared to the waviness number (m) of the undulations. The magnitude of heat (Nu) and mass (Sh) transfer rate for the W-shaped cavity is high compared to conventional square and trapezoidal-shaped cavities. The output of the analysis could be very helpful for the designer for modeling devices operating on nanotechnology-based bioconvection, microbial fuel cells, and others.}, language = {en} } @article{BenimCanalBoke2021, author = {Benim, Ali Cemal and Canal, Cansu Deniz and Boke, Yakup Erhan}, title = {A Validation Study for RANS Based Modelling of Swirling Pulverized Fuel Flames}, series = {Energies}, volume = {14}, journal = {Energies}, number = {21}, publisher = {MDPI}, issn = {1996-1073}, doi = {10.3390/en14217323}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-37365}, year = {2021}, abstract = {A swirling pulverized coal flame is computationally investigated. A Eulerian-Lagrangian formulation is used to describe the two-phase flow. Turbulence is modelled within a RANS (Reynolds averaged numerical simulation) framework. Four turbulence viscosity- (TV) based models, namely the standard k-ε model, realizable k-ε model, renormalization group theory k-ε model, and the shear stress transport k-ω model are used. In addition, a Reynolds stress transport model (RSM) is employed. The models are assessed by comparing the predicted velocity fields with the measurements of other authors. In terms of overall average values, the agreement of the predictions to the measurements is observed to be within the range 20-40\%. A better performance of the RSM compared to the TV models is observed, with a nearly twice as better overall agreement to the experiments, particularly for the swirl velocity. In the second part of the investigation, the resolution of the discrete particle phase in modelling the turbulent particle dispersion (TPD) and particle size distribution (SD) is investigated. Using the discrete random walk model for the TPD, it is shown that even five random walks are sufficient for an accuracy that is quite high, with a less than 1\% mean deviation from the solution obtained by thirty random walks. The approximation of the measured SD is determined by a continuous Rosin-Rammler distribution function, and inaccuracies that can occur in its subsequent discretization are demonstrated and discussed. An investigation on the resolution of the SD by discrete particle size classes (SC) indicates that 12 SC are required for an accuracy with a less than 1\% mean deviation from the solution with 18 SC. Although these numbers may not necessarily be claimed to be sufficiently universal, they may serve as guidance, at least for SD with similar characteristics}, language = {en} } @article{SenthurAnandRameshKumaretal.2022, author = {Senthur, N.S. and Anand, C and Ramesh Kumar, M and Elumalai, P.V. and Shajahan, Mohamed Iqbal and Benim, Ali Cemal and Nasr, Emad Abouel and Hussein, H.M.A. and Parthasarathy, M.}, title = {Influence of cobalt chromium nanoparticles in homogeneous charge compression ignition engine operated with citronella oil}, series = {Energy Science \& Engineering}, volume = {10}, journal = {Energy Science \& Engineering}, number = {4}, publisher = {Wiley}, issn = {2050-0505}, doi = {10.1002/ese3.1088}, pages = {1251 -- 1263}, year = {2022}, language = {en} } @article{PfeiffelmannBenimJoos2021, author = {Pfeiffelmann, Bj{\"o}rn and Benim, Ali Cemal and Joos, Franz}, title = {Water-Cooled Thermoelectric Generators for Improved Net Output Power: A Review}, series = {Energies}, volume = {14}, journal = {Energies}, number = {24}, publisher = {MDPI}, issn = {1996-1073}, doi = {10.3390/en14248329}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-37323}, year = {2021}, abstract = {Thermoelectric generators (TEGs) have the ability to convert waste heat into electrical energy under unfavorable conditions and are becoming increasingly popular in academia, but have not yet achieved a broad commercial success, due to the still comparably low efficiency. To increase the efficiency and economic viability of TEGs, research is performed on the materials on one hand and on the system connection on the other. In the latter case, the net output power of the cooling system plays a key role. At first glance, passive cooling seems preferable to active cooling because it does not affect the net electrical output power. However, as shown in the present review, the active cooling is to be preferred for net output power. The situation is similar in air and water-cooling. Even though air-cooling is easier to set up, the water-cooling should be preferred to achieve higher net output power. It is shown that microchannel cooling has similar hydraulic performance to conventional cooling and inserts increase the net output power of TEG. As the review reveals that active water-cooling should be the method of choice to achieve high net output power, it also shows that a careful optimization is necessary to exploit the potential.}, language = {en} } @article{Benim2021, author = {Benim, Ali Cemal}, title = {Numerical Calculation of Sink Velocities for Helminth Eggs in Water}, series = {Computation}, volume = {9}, journal = {Computation}, number = {12}, publisher = {MDPI}, issn = {2079-3197}, doi = {10.3390/computation9120136}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-37318}, year = {2021}, abstract = {The settling velocities of helminth eggs of three types, namely Ascaris suum (ASC), Trichuris suis (TRI), and Oesophagostomum spp. (OES), in clean tap water are computationally determined by means of computational fluid dynamics, using the general-purpose CFD software ANSYS Fluent 18.0. The previous measurements of other authors are taken as the basis for the problem formulation and validation, whereby the latter is performed by comparing the predicted sink velocities with those measured in an Owen tube. To enable a computational treatment, the measured shapes of the eggs are parametrized by idealizing them in terms of elementary geometric forms. As the egg shapes show a variation within each class, "mean" shapes are considered. The sink velocities are obtained through the computationally obtained drag coefficients. The latter are defined by means of steady-state calculations. Predicted sink velocities are compared with the measured ones. It is observed that the calculated values show a better agreement with the measurements, for ASC and TRI, compared to the theoretical sink values delivered by the Stokes theory. However, the observed agreement is still found not to be very satisfactory, indicating the role of further parameters, such as the uncertainties in the characterization of egg shapes or flocculation effects even in clean tap water.}, language = {en} } @article{DeckertSchomaker2022, author = {Deckert, Carsten and Schomaker, Rahel M.}, title = {Cultural tightness-looseness and national innovativeness: impacts of tolerance and diversity of opinion}, series = {Journal of Innovation and Entrepreneurship}, volume = {11}, journal = {Journal of Innovation and Entrepreneurship}, publisher = {Springer Nature}, issn = {2192-5372}, doi = {10.1186/s13731-022-00219-2}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-36515}, pages = {1 -- 19}, year = {2022}, abstract = {The links between innovativeness as a driver of economic performance, and the determinants of innovativeness have been investigated by management scholars and economists for decades, focusing mostly on "hard factors" as investment in research and development, or education. Focusing on a relatively neglected, but in times of globalization even more important aspect, the infuence of cultural characteristics on innovativeness, we apply diferent econometric models to test for links between cultural tightness and looseness on the one hand, and national innovativeness on the other hand. We fnd that cultural tightness—in the sense of homogenous and intolerant societies—has a negative link to national innovativeness, while cultural looseness—in the sense of tolerant and diverse societies—displays a positive link to national innovativeness.}, subject = {Innovation}, language = {en} } @article{GirodBreitkreuzHenningetal.2019, author = {Girod, Kai and Breitkreuz, Klaas and Henning, Torsten and Lohmann, Heiko and Kaluza, Stefan and Schluter, Stefan}, title = {Steel Mills as Syngas Source for Methanol Synthesis: Simulation and Practical Performance Investigations}, series = {Chemical Engineering Transactions}, volume = {74}, journal = {Chemical Engineering Transactions}, publisher = {AIDIC}, isbn = {978-88-95608-71-6}, issn = {2283-9216}, doi = {10.3303/CET1974080}, pages = {475 -- 480}, year = {2019}, abstract = {In the present contribution, the utilization of steel-mill gases for an industrial methanol synthesis process is described. The focus of this work is on the influence of syngas compositions derived from steel-mill gases on an industrial Cu/ZnO/Al2O3 catalyst. Elevated CO2 and H2O concentrations seem to have an irreversible impact on the activity of the catalyst. In order to obtain realistic gas composition for the catalyst tests, a process simulation of the methanol synthesis was conducted. The calculated gas compositions at the reactor inlet were applied in a practical test in order to evaluate the catalyst stability under steel mill gas conditions. No noticeable deactivation was observed.}, language = {en} } @article{ReichGottschaldRiegebaueretal.2020, author = {Reich, Marius and Gottschald, Jonas and Riegebauer, Philipp and Adam, Mario}, title = {Predictive Control of District Heating System Using Multi-Stage Nonlinear Approximation with Selective Memory}, series = {Energies}, volume = {13}, journal = {Energies}, number = {24}, publisher = {MDPI}, issn = {1996-1073}, doi = {10.3390/en13246714}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-33627}, year = {2020}, language = {en} }