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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.
Heterogeneous catalysts usually consist of porous, inorganic materials. Especially in the mobile application, e.g., in exhaust gas catalysis as a part of the gas line of an engine, there are loads due to vibrations and high gas velocities. It can be assumed that physical stress will lead to a loss of the catalytically active coating. The present contribution describes experimental setups and methods for a systematic and reproducible investigation of the main influences to the mass loss due to vibrational and fluid‐mechanical stress caused by particle‐free gas flows.
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.
Methanol Synthesis with Steel Mill Gases: Performance Investigations in an On‐Site Technical Center
(2021)
Management des Innovationsportfolios: Portfolio-Matrizen zumManagement von Innovationsprojekten
(2021)
Von Maschinenbau-Ingenieur*innen wird oft erwartet, innovative Produkte, Dienstleistungen oder Prozesse zu entwickeln und zu vermarkten. Das Ziel der vorliegenden Arbeit ist es herauszufinden, inwiefern sie bereits im Masterstudium Maschinenbau durch die Förderung von Kreativität und Entrepreneurship darauf vorbereitet werden. Um die Forschungsfrage zu beantworten, wurden die Modulhandbücher der zehn größten Universitäten sowie Fachhochschulen mithilfe einer Schlagwortsuche auf einschlägige Begriffe analysiert. Die Studie zeigt, dass deutsche Ingenieur*innen sowohl an Fachhochschulen als auch an Universitäten hinsichtlich Kreativität und Entrepreneurship eher unzureichend ausgebildet werden.
This paper investigates the implementation of a human body model for the simulation of a jumping motion in Simulink. It contains details to get an insight into modern biomechanics without previous experience. In the simulation, a Hill-Type muscle is used to generate joint momentum with a phenomenologically realistic relationship between muscle length and force. The simulation published with this article is one of many solutions to design a humanoid simulation. The paper guides through the implemented build and explains its range of application.
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
Today, the use of renewable energies and recycling of climate-changing gases are increasingly important. In this context,coupling of methanation with small, decentralized CO2sources such as biogas plants provides one possibility. However,fluctuating availability of renewables for hydrogen production in combination with small storage volumes result in anenhanced demand for dynamic process operation. This leads to new research challenges with respect to the required cata-lysts and the overall process design. To draw reliable conclusions about the catalytic performance under dynamic processoperation, the mechanism of the methanation reaction as well as typical deactivation procedures of the catalyst appliedunder steady-state conditions have to be reviewed thoroughly.
Aufgrund der §§ 2 Abs. 4, 64 Abs. 1 des Gesetzes über die Hochschulen des Landes Nordrhein-Westfalen (Hochschulgesetz - HG) vom 16.09.2014 (GV. NRW. S. 547) in der aktuell gültigen Fassung hat die Hochschule Düsseldorf die folgende studiengangspezifische Prüfungsordnung als Satzung erlassen. Diese Prüfungsordnung gilt nur in Verbindung mit der Rahmenprüfungsordnung des Fachbereichs Maschinenbau und Verfahrenstechnik der Hochschule Düsseldorf (RahmenPO) vom 15.02.2016 in der jeweils gültigen Fassung.
Aufgrund der §§ 2 Abs. 4, 64 Abs. 1 des Gesetzes über die Hochschulen des Landes Nordrhein-Westfalen (Hochschulgesetz - HG) vom 16.09.2014 (GV. NRW. S. 547) in der aktuell gültigen Fassung hat die Hochschule Düsseldorf die folgende studiengangspezifische Prüfungsordnung als Satzung erlas-sen. Diese Prüfungsordnung gilt nur in Verbindung mit der Rahmenprüfungsordnung des Fachbereichs Maschinenbau und Verfahrenstechnik der Hochschule Düsseldorf (RahmenPO) vom 15.02.2016 in der jeweils gültigen Fassung.
Aufgrund der §§ 2 Abs. 4, 64 Abs. 1 des Gesetzes über die Hochschulen des Landes Nordrhein-Westfalen (Hochschulgesetz - HG) vom 16.09.2014 (GV. NRW. S. 547) in der aktuell gültigen Fassung hat die Hochschule Düsseldorf die folgende studiengangspezifische Prüfungsordnung als Satzung erlas-sen. Diese Prüfungsordnung gilt nur in Verbindung mit der Rahmenprüfungsordnung des Fachbereichs Maschinenbau und Verfahrenstechnik der Hochschule Düsseldorf (RahmenPO) vom 15.02.2016 in der jeweils gültigen Fassung.
Aufgrund der §§ 2 Abs. 4, 64 Abs. 1 des Gesetzes über die Hochschulen des Landes Nordrhein-Westfalen (Hochschulgesetz - HG) vom 16.09.2014 (GV. NRW. S. 547) in der aktuell gültigen Fassung hat die Hochschule Düsseldorf die folgende studiengangspezifische Prüfungsordnung als Sat-zung erlassen. Diese Prüfungsordnung gilt nur in Verbindung mit der Rahmenprüfungsordnung des Fachbereichs Maschinenbau und Verfahrenstechnik der Hochschule Düsseldorf (RahmenPO) vom 15.02.2016 in der jeweils gültigen Fassung.