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Planung neuer Deponien
(1987)
Abfallwirtschaft
(2007)
Abfallwirtschaft
(2007)
Abfallwirtschaft
(2012)
Abfallwirtschaft
(2012)
Abfallwirtschaft
(2009)
Abfallwirtschaft
(2015)
Abfallwirtschaft
(2015)
Die Eignung von Baggergut als mineralische Komponente in Deponie-Oberflächenabdichtungssystemen
(2003)
Sanierung des ehemaligen Gaswerkgeländes am Bremer Hauptbahnhof / K. Konertz ; E. Biener ; T. Sasse
(2003)
Schäden an Talsperren
(1984)
Koaxiale Stahlenergiepfähle
(2021)
Ein entscheidender Teil der Energiewende ist die Wärmewende im Gebäudesektor. Ein Schlüsselelement sind hier Wärmepumpen. Diese benötigen eine Wärmequelle, der sie Energie entziehen können, um sie auf ein höheres Temperaturniveau zu transformieren. Diese Wärmequelle kann bspw. das Erdreich sein, dessen Wärme durch Erdsonden erschlossen werden kann. In diesem Beitrag werden in Stahlpfähle integrierte Koaxialsonden mit dem Stand der Technik von Erdsonden gleichen Durchmessers bezüglich ihrer thermischen Leistungsmerkmale verglichen. Die Stahlenergiepfähle bieten neben der Wärmegewinnung weitere Vorteile, da sie auch eine statische Funktion übernehmen und rückstandsfrei zurückgebaut werden können. Es werden analytische und numerische Berechnungen vorgestellt, um die thermischen Potenziale beider Systeme zu vergleichen. Außerdem wird ein Testaufbau gezeigt, bei dem Stahlenergiepfähle in zwei verschiedenen Längen mit vorhandenen gängigen Erdsonden verglichen werden können. Die Berechnungen zeigen einen deutlichen thermischen Mehrertrag zwischen 26 % und 148 % der Stahlenergiepfähle gegenüber dem Stand der Technik abhängig vom Erdreich. Die Messergebnisse zeigen einen thermischen Mehrertrag von über 100 %. Es lässt sich also signifikante Erdsondenlänge einsparen. Dabei ist zu beachten, dass sich damit der thermisch genutzte Bereich des Erdreichs reduziert, wodurch die thermische Regeneration und/oder das Langzeitverhalten des Erdreichs an Bedeutung gewinnt.
Using optimization to design a renewable energy system has become a computationally demanding task as the high temporal fluctuations of demand and supply arise within the considered time series. The aggregation of typical operation periods has become a popular method to reduce effort. These operation periods are modelled independently and cannot interact in most cases. Consequently, seasonal storage is not reproducible. This inability can lead to a significant error, especially for energy systems with a high share of fluctuating renewable energy. The previous paper, “Time series aggregation for energy system design: Modeling seasonal storage”, has developed a seasonal storage model to address this issue. Simultaneously, the paper “Optimal design of multi-energy systems with seasonal storage” has developed a different approach. This paper aims to review these models and extend the first model. The extension is a mathematical reformulation to decrease the number of variables and constraints. Furthermore, it aims to reduce the calculation time while achieving the same results.
Optimierung des potentiellen Sauerstoffeintrags auf Treppenschussrinnen mit gemäßigter Neigung
(2009)
Sensitivity of phase detection techniques in aerated chute flows to hydraulic design parameters
(2012)
Hydraulic modeling is the classical approach to investigate and describe complex fluid motion. Many empirical formulas in the literature used for the hydraulic design of river training measures and structures have been developed using experimental data from the laboratory. Although computer capacities have increased to a high level which allows to run complex numerical simulations on standard workstation nowadays, non-standard design of structures may still raise the need to perform physical model investigations. These investigations deliver insight into details of flow patterns and the effect of varying boundary conditions. Data from hydraulic model tests may be used for calibration of numerical models as well. As the field of hydraulic modeling is very complex, this chapter intends to give a short overview on capacities and limits of hydraulic modeling in regard to river flows and hydraulic structures only. The reader shall get a first idea of modeling principles and basic considerations. More detailed information can be found in the references.
Optimization of the reaeration potential on embankment stepped spillways in skimming flow regime
(2008)
Application of the optical flow method to velocity determination in hydraulic structure models
(2016)
As with most high-velocity free-surface flows, stepped spillway flows become self-aerated when the drop height exceeds a critical value. Due to the step-induced macro-roughness, the flow field becomes more turbulent than on a similar smooth-invert chute. For this reason, cascades are oftentimes used as re-aeration structures in wastewater treatment. However, for stepped spillways as flood release structures downstream of deoxygenated reservoirs, gas transfer is also of crucial significance to meet ecological requirements. Prediction of mass transfer velocities becomes challenging, as the flow regime differs from typical previously studied flow conditions. In this paper, detailed air-water flow measurements are conducted on stepped spillway models with different geometry, with the aim to estimate the specific air-water interface. Re-aeration performances are determined by applying the absorption method. In contrast to earlier studies, the aerated water body is considered a continuous mixture up to a level where 75% air concentration is reached. Above this level, a homogenous surface wave field is considered, which is found to significantly affect the total air-water interface available for mass transfer. Geometrical characteristics of these surface waves are obtained from high-speed camera investigations. The results show that both the mean air concentration and the mean flow velocity have influence on the mass transfer. Finally, an empirical relationship for the mass transfer on stepped spillway models is proposed.
Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents the first study on application of the optical flow method to aerated stepped spillway flows. For this purpose, the flow is captured with a high-speed camera and illuminated with a synchronized LED light source. The flow velocities, obtained using a basic Horn–Schunck method for estimation of the optical flow coupled with an image pyramid multi-resolution approach for image filtering, compare well with data from intrusive conductivity probe measurements. Application of the Horn–Schunck method yields densely populated flow field data sets with velocity information for every pixel. It is found that the image pyramid approach has the most significant effect on the accuracy compared to other image processing techniques. However, the final results show some dependency on the pixel intensity distribution, with better accuracy found for grey values between 100 and 150.