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The results of physical modeling of flow in an axial cyclone combustion chamber; Ergebnisse physikalischer Modellierung der Stroemung in einer Axialzyklonbrennkammer  

Energy Technology Data Exchange (ETDEWEB)

The isothermal flow field for the axial cyclone has been experimentally determined. The velocity fields are used for determination particle paths (particle removal and suspended state), and inter alia of heat and mass transfer processes in the axial cyclone combustion chamber. The results are extremely significant as input value approximations for mathematical modelling, since experimentally obtained results are indispensable for complex flows and geometries. (orig.) [Deutsch] Es ist fuer den Axialzyklon experimentell das isotherme Stroemungsfeld ermittelt. Die Geschwindigkeitsfelder dienen zur Ermittlung der Partikelbahnen (Partikelabscheidung, Schwebebedingung), der Waerme- und Stoffuebertragungsprozesse u.a. in der Axialzyklonbrennkammer. Die Ergebnisse sind als Startwertnaeherung bei einer mathematischen Modellierung sehr wichtig, da bei komplexen Stroemungen und Geometrien versuchstechnische Ergebnisse unumgaenglich sind. (orig.)

1994-12-31

2

Short circuit strength of surface mounted 110 kV cables; Kurzschlussverhalten von 110-kV-Kabeln in offener Legung  

Energy Technology Data Exchange (ETDEWEB)

The danger potential for 110 kV cables, which are installed on racks and in tunnels, caused by catching fire because of arcing short circuits and mechanical overstressing by peak shortcircuit current, has been experimental analysed under Bewag network conditions. As a result, recommendations for an improved installation of 110 kV cables are given. (orig.) [Deutsch] Fuer offen gelegte 110-kV-Kabel in Raeumen, auf Fussboeden und in Schaechten wurde das von Kurzschluessen auf den Kabeln ausgehende Gefaehrdungspotential fuer die Entstehung von Kabelbraenden durch Fehlerlichtboegen und fuer eine mechanische Ueberbeanspruchung von Kabeln durch Stosskurzschlussstroeme unter Beruecksichtigung der Netzverhaeltnisse der Bewag experimentell untersucht. Im Ergebnis geben die Verfasser Empfehlungen fuer die sichere Anordnung offen gelegter 110-kV-Kabel. (orig.)

1998-03-23

3

Proactive product and process qualification in steam turbine development; Proaktive Produkt- und Prozessqualifikation in der Dampfturbinenentwicklung  

Energy Technology Data Exchange (ETDEWEB)

Proactive qualification is today an integral part of the development process for steam turbines used in steam and combined cycle power plants. By providing experimentally based `random` variables, such as the steam path efficiency and blading reliability, it makes a valuable contribution to the economic `random` variables of the power plant, e.g. the rate of return, as viewed by the customer. One of the areas in which proactive product and process qualification plays an important role is the development of LP steam paths. (orig.) [Deutsch] Die proaktive Qualifikation ist heute fester Bestandteil des Entwicklungsprozesses bei Dampfturbinen, die fuer den Einsatz in Dampf- und Kombikraftwerken bestimmt sind. Sie leistet mit Hilfe experimentell ermittelter `Zufalls`-Variablen, wie z.B. Wirkungsgrad der Fluten und Zuverlaessigkeit der Beschaufelungen, einen wertvollen Beitrag zu den fuer die Kunden wichtigen wirtschaftlichen `Zufalls`-Variablen des Kraftwerks, wie etwa ...

1998-10-01

4

Phenomenological modelling of heat transfer at the gas side wall of diesel engines; Phaenomenologische Modellbildung des gasseitigen Wandwaermeueberganges in Dieselmotoren  

Energy Technology Data Exchange (ETDEWEB)

A phenomenological model of the heat transfer in direct injection diesel engines was developed. Utilizing the thermodynamic results of a combustion model as an input, the model is able to predict the temporal variation of the heat losses from the cylinder gas to the cylinder walls. Additionally, the division into isothermal combustion chamber subsurfaces allows the consideration of the spatial variation of the wall heat fluxes. The physical mechanisms such as flow dependent convection, heat radiation due to hot soot particles and isolation effects of deposited soot layers are described in detail. Thus the effects of these mechanisms on the overall heat transfer can be studied. The heat transfer model was verified successfully by the comparison to measured wall heat fluxes in a single-cylinder direct injection diesel engine. It is shown that the effects of engine speed and load, turbocharging and soot deposition can be predicted with good accuracy. [German] Es wurde ein ...

2000-07-01

5

Optimising the flow characteristic of a coke-oven flue-gas valve by means of Computational Fluid Dynamics (CFD); Stroemungsoptimierung eines Abgasventils von Koksoefen durch Computational Fluid Dynamics (CFD)  

Energy Technology Data Exchange (ETDEWEB)

In coke-oven operations flue-gas valves are used to switch the regenerator function from rich gas firing to lean gas firing. Compared with the simple geometry of the other parts of the flow path, which comprise flues and regenerators, the narrow and winding passages of the flue-gas valves give rise to relatively high losses in pressure. Without the construction of high (and therefore expensive) chimneys, this means that operating problems may well arise due the inadequate suction capacity. The project focused on the theoretical and experimental analysis of a coke-oven flue-gas valve. The primary aim was to reduce the pressure drop through the valve without modifying its external geomerty. The internal flow characteristics created by different valve geometries under a variety of operating conditions were simulated using the commercial CFD code Fluent/UNS, which provided velocity and pressure distributions. A half-scale model valve was constructed in order to characterise the internal ...

1999-06-01

6

Effects of ductile particles on the toughness and deformation characteristics of NiAl matrix materials; Einfluss duktiler Teilchen auf die Zaehigkeit und das Verformungsverhalten von NiAl-Matrix-Werkstoffen  

Energy Technology Data Exchange (ETDEWEB)

The intermetallic phase NiAl is a potential material for high-temperature applications; however, its technical application was prevented so far by its high brittleness at room temperature. This problem may be solved by incorporating relatively high-ductility particles into the NiAl matrix. Controlled crack propagation experiments, tensile and pressure tests were carried out in order to analyze the toughness and deformation characteristics of NiAl composite materials containing niobium or molybdenum particles at room temperature and in ambient atmosphere. Both the niobium and the molybdenum particles increase the toughness as compared to the pure NiAl matrix, but no ductilisation was observed in the composite materials investigated. Model experiments in consideration of experimental data suggest, hovewer, that the toughness and ductility of NiAl may be enhanced by optimizing the microstructural and production parameters of the incorporated ductile particles. (orig.) [Deutsch] Die ...

1995-12-31

7

QUEOS, a simulation-experiment of the premixing phase of a steam explosion with hot spheres in water base case experiments  

Energy Technology Data Exchange (ETDEWEB)

This report describes the QUEOS facility and gives the results of the first test series performed up to 6/1995. The premixing phase of a steam explosion is investigated experimentally with simulant materials. The transient three-dimensional multi-component interaction of molten corium with water is studied using a large number of small solid spheres at temperatures up to 2300 C. The objective of the experiments is to establish a data base for testing the models of heat and momentum transfer in multi-fluid codes as well as the code`s capability to correctly describe multiphase flows. The experiments have the advantage that the diameter of the `coarse melt fragments` are known and that detailed measurements can be performed without the danger of a steam explosion. In this first series of experiments up to 10 kg of spheres (max. 24000 pieces) were used. The spheres, made of molybdenum or zirconia, were heated to temperatures up to 2000 C and are discharged into 0.5 m{sup 3} of saturated ...

1996-04-01

8

Measurement of level lifetimes in the ps range and model interpretations for neutron-rich A {approx_equal} 100 nuclei  

Energy Technology Data Exchange (ETDEWEB)

The nuclear structure of A {proportional_to} 100 nuclei has been studied in the frame of this thesis with a recently developed {beta} - {gamma} - {gamma} triple coincidence fast timing technique and different models such as shell model, hydrodynamic model, Nilsson and particle-rotor models. This technique which allows the measurement of the level lifetimes in the ps range has been applied at JOSEF at the research reactor DIDO of KFA Juelich in studes of the short-lived neutron-rich nuclei in the A {approx_equal} 100 region. Lifetimes of level in {sup 96},{sup 98},{sup 100} ZR, {sup 99},{sup 101}-{sup 104} Nb, {sup 100}-{sup 105} Mo have been measured, which are in many cases completely new, and otherwise more precise than previously published data. From the lifetimes of the members of rotational bands, the size of the nuclear deformations has been deduced. (orig./HSI). [Deutsch] Im Rahmen dieser Doktorarbeit wurde die Kernstruktur der A {proportional_to} 100 Kerne untersucht. Dazu ...

1992-08-01

9

Poly-lactic-acid coating of endovascular stents: preliminary results in canine experimental av-fistulae  

Energy Technology Data Exchange (ETDEWEB)

Poly-Lactic-Acid (PLA) was evaluated for coating of vascular endoprotheses in the treatment of experimental arterio-venous-fistulae (AVF). Bilateral carotid-external jugular AVF were created in 5 adult dogs. 7 PLA coated nitinol stents were placed via a transfemoral approach covering 5 AVF. The contralateral AVF remained untreated. Angiography was performed immediately after stent placement, at weeks 1 and 3 and at months 3, 6 and 9. All grafts were removed and underwent histologic examination. In 2 cases the occlusion of the AVF was successful, while misplacement occurred in 3 cases. Occlusion of the parent vessel was disclosed in 3 cases. Histologic examination revealed a mild inflammatory reaction with the presence of macrophages. There was no foreign-body reaction or fragmentation of the arterial vessel wall. PLA, which is a well-known biodegradable material, showed a good mid-term biocompatibility. Elastic mismatch of the non-elastic coating and the self-expandable nitinol stent ...

2001-02-01

10

A micromachined high pressure stable mass flow sensor for common-rail injection systems; Ein mikromechanisch gefertigter hochdruckstabiler Massenflusssensor fuer Common-Rail(CR)-Einspritzsysteme  

Energy Technology Data Exchange (ETDEWEB)

We report for the first time about a micromachined mass flow sensor directly integrated between the double guidance and the needle seat into the body of a Common Rail (CR) injection nozzle. The thermal measurement principle was chosen because gaseous as well as liquid mass flows can be determined fast and precisely. Additionally, with glass-ceramic materials fabricated in a low cost batch process, a high temperature and especially pressure stable substrate can be used. The flow sensitive thin film is realized by an e-beam evaporated 110 nm thick molybdenum (Mo) layer. The latter is electrically characterized by the resistivity of {rho} = 8.2 x 10{sup -7} {omega} m ({+-}2%) at room temperature as well as by the first {alpha}=4.5 x 10{sup -4} K{sup -1} ({+-}5%) and second {beta}=3.0 x 10{sup -6} K{sup -2} ({+-}12%) temperature coefficients of resistance up to 300 C. The static temperature field at and around the thin film sensor on the glass-ceramic substrate is investigated with an IR ...

2001-05-01

11

Investigation of dominant loss mechanisms in low-temperature polymer electrolyte membrane fuel cells  

Energy Technology Data Exchange (ETDEWEB)

This thesis deals with the analysis of dominant loss mechanisms in direct methanol fuel cells (DMFC) and hydrogen fed polymer electrolyte membrane fuel cells (PEFC) by means of experimental characterization and modeling work. Due to different fuels used in these two fuel cell types, the dominant loss mechanisms are different in their nature. All in-situ characterization techniques that are used in this work are based on a novel test fuel cell with embedded reference electrodes. The first part of this work presents a new concept for realizing a reference electrode configuration in a polymer electrolyte membrane fuel cell by means of laser ablation. The laser beam is used to evaporate a small gap into the electrode surface of a catalyst coated membrane (CCM) to isolate the reference electrode from the working/counter electrode (WE/CE). This method enables the simultaneous ablation of the electrodes on both sides of the CCM because the membrane is transparent for the laser beam. ...

2010-07-01