TY - JOUR A1 - Biedermann, Till M. A1 - Czeckay, Pasquale A1 - Hintzen, Nils A1 - Kameier, Frank A1 - Paschereit, C. O. T1 - Applicability of Aeroacoustic Scaling Laws of Leading Edge Serrations for Rotating Applications JF - acoustics KW - DOAJ KW - ISAVE Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-40311 SN - 2624-599X VL - 2 IS - 3 SP - 579 EP - 594 PB - MDPI ER - TY - JOUR A1 - Mabrouk, Riheb A1 - Naji, Hassane A1 - Benim, Ali Cemal A1 - Dhahri, Hacen T1 - A State of the Art Review on Sensible and Latent Heat Thermal Energy Storage Processes in Porous Media: Mesoscopic Simulation JF - Applied Sciences KW - DOAJ Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-40343 VL - 12 IS - 14 PB - MDPI ER - TY - JOUR A1 - Biswas, Nirmalendu A1 - Mandal, Dipak Kumar A1 - Manna, Nirmal K. A1 - Benim, Ali Cemal T1 - Magneto-hydrothermal triple-convection in a W-shaped porous cavity containing oxytactic bacteria JF - scientific reports N2 - 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. KW - DOAJ Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-40041 SN - 2045-2322 VL - 12 PB - Springer Nature ER - TY - JOUR A1 - Benim, Ali Cemal A1 - Canal, Cansu Deniz A1 - Boke, Yakup Erhan T1 - A Validation Study for RANS Based Modelling of Swirling Pulverized Fuel Flames JF - Energies N2 - 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 KW - DOAJ Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-37365 SN - 1996-1073 VL - 14 IS - 21 PB - MDPI ER - TY - JOUR A1 - Senthur, N.S. A1 - Anand, C A1 - Ramesh Kumar, M A1 - Elumalai, P.V. A1 - Shajahan, Mohamed Iqbal A1 - Benim, Ali Cemal A1 - Nasr, Emad Abouel A1 - Hussein, H.M.A. A1 - Parthasarathy, M. T1 - Influence of cobalt chromium nanoparticles in homogeneous charge compression ignition engine operated with citronella oil JF - Energy Science & Engineering KW - General Energy KW - Safety, Risk, Reliability and Quality KW - DOAJ Y1 - 2022 U6 - https://doi.org/10.1002/ese3.1088 SN - 2050-0505 VL - 10 IS - 4 SP - 1251 EP - 1263 PB - Wiley ER - TY - JOUR A1 - Pfeiffelmann, Björn A1 - Benim, Ali Cemal A1 - Joos, Franz T1 - Water-Cooled Thermoelectric Generators for Improved Net Output Power: A Review JF - Energies N2 - 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. KW - Energy Engineering and Power Technology KW - Renewable Energy, Sustainability and the Environment KW - Electrical and Electronic Engineering KW - Control and Optimization KW - DOAJ Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-37323 SN - 1996-1073 VL - 14 IS - 24 PB - MDPI ER - TY - JOUR A1 - Benim, Ali Cemal T1 - Numerical Calculation of Sink Velocities for Helminth Eggs in Water JF - Computation N2 - 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. KW - Applied Mathematics KW - Modeling and Simulation KW - General Computer Science KW - Theoretical Computer Science KW - DOAJ Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-37318 SN - 2079-3197 VL - 9 IS - 12 PB - MDPI ER - TY - JOUR A1 - Deckert, Carsten A1 - Schomaker, Rahel M. T1 - Cultural tightness–looseness and national innovativeness: impacts of tolerance and diversity of opinion JF - Journal of Innovation and Entrepreneurship N2 - 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. KW - DOAJ KW - DEAL KW - Innovation KW - Kultur KW - Toleranz KW - Diversity of opinion Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-36515 SN - 2192-5372 VL - 11 SP - 1 EP - 19 PB - Springer Nature ER - TY - JOUR A1 - Girod, Kai A1 - Breitkreuz, Klaas A1 - Henning, Torsten A1 - Lohmann, Heiko A1 - Kaluza, Stefan A1 - Schluter, Stefan T1 - Steel Mills as Syngas Source for Methanol Synthesis: Simulation and Practical Performance Investigations JF - Chemical Engineering Transactions N2 - 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. KW - DOAJ Y1 - 2019 SN - 978-88-95608-71-6 U6 - https://doi.org/10.3303/CET1974080 SN - 2283-9216 VL - 74 SP - 475 EP - 480 PB - AIDIC ER - TY - JOUR A1 - Reich, Marius A1 - Gottschald, Jonas A1 - Riegebauer, Philipp A1 - Adam, Mario T1 - Predictive Control of District Heating System Using Multi-Stage Nonlinear Approximation with Selective Memory JF - Energies KW - BestHeatNet KW - DOAJ Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-33627 SN - 1996-1073 VL - 13 IS - 24 PB - MDPI ER -