TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. A1 - Crookston, B.M. T1 - Energy dissipation of a Type III basin under design and adverse conditions for stepped and smooth spillways JF - Journal of Hydraulic Engineering N2 - New information regarding the influence of a stepped chute on the hydraulic performance of the United States Bureau of Reclamation (Reclamation) Type III hydraulic jump stilling basin is presented for design (steady) and adverse (decreasing tailwater) conditions. Using published experimental data and computational fluid dynamics (CFD) models, this paper presents a detailed comparison between smooth-chute and stepped-chute configurations for chute slopes of 0.8H:1V and 4H:1V and Froude numbers (F) ranging from 3.1 to 9.5 for a Type III basin designed for F = 8. For both stepped and smooth chutes, the relative role of each basin element was quantified, up to the most hydraulic extreme case of jump sweep-out. It was found that, relative to a smooth chute, the turbulence generated by a stepped chute causes a higher maximum velocity decay within the stilling basin, which represents an enhancement of the Type III basin’s performance but also a change in the relative role of the basin elements. Results provide insight into the ability of the CFD models [unsteady Reynolds-averaged Navier-Stokes (RANS) equations with renormalization group (RNG) k-ϵ turbulence model and volume-of-fluid (VOF) for free surface tracking] to predict the transient basin flow structure and velocity profiles. Type III basins can perform adequately with a stepped chute despite the effects steps have on the relative role of each basin element. It is concluded that the classic Type III basin design, based upon methodology by reclamation specific to smooth chutes, can be hydraulically improved for the case of stepped chutes for design and adverse flow conditions using the information presented herein. Y1 - 2018 U6 - http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0001482 SN - 0733-9429 N1 - Article number 04018036 VL - 144 IS - 7 PB - ASCE CY - Reston, Va. ER - TY - JOUR A1 - Kerres, Karsten A1 - Siekmann, Marko T1 - Wie kommuniziere ich prognosegestützte Instandhaltungsstrategien erfolgreich in politischen Entscheidungsgremien? JF - 3 R. Fachzeitschrift für sichere und effiziente Rohleitungssysteme Y1 - 2018 SN - 2191-9798 IS - 12 SP - 47 EP - 51 PB - Vulkan-Verl. CY - Essen ER - TY - JOUR A1 - Zhang, G. A1 - Valero, Daniel A1 - Bung, Daniel B. A1 - Chanson, H. T1 - On the estimation of free-surface turbulence using ultrasonic sensors JF - Flow Measurement and Instrumentation N2 - Accurate determination of free-surface dynamics has attracted much research attention during the past decade and has important applications in many environmental and water related areas. In this study, the free-surface dynamics in several turbulent flows commonly found in nature were investigated using a synchronised setup consisting of an ultrasonic sensor and a high-speed video camera. Basic sensor capabilities were examined in dry conditions to allow for a better characterisation of the present sensor model. The ultrasonic sensor was found to adequately reproduce free-surface dynamics up to the second order, especially in two-dimensional scenarios with the most energetic modes in the low frequency range. The sensor frequency response was satisfactory in the sub-20 Hz band, and its signal quality may be further improved by low-pass filtering prior to digitisation. The application of the USS to characterise entrapped air in high-velocity flows is also discussed. Y1 - 2018 U6 - http://dx.doi.org/10.1016/j.flowmeasinst.2018.02.009 SN - 0955-5986 VL - 60 SP - 171 EP - 184 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bung, Daniel B. A1 - Valero, Daniel T1 - Re-aeration on stepped spillways with special consideration of entrained and entrapped air JF - Geosciences N2 - 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. Y1 - 2018 SN - 2076-3263 VL - 8 IS - 9 SP - Article number 333 PB - MDPI CY - Basel ER - TY - JOUR A1 - Kramer, Matthias A1 - Valero, Daniel A1 - Chanson, Hubert A1 - Bung, Daniel B. T1 - Towards reliable turbulence estimations with phase-detection probes: an adaptive window cross-correlation technique JF - Experiments in Fluids Y1 - 2019 U6 - http://dx.doi.org/10.1007/s00348-018-2650-9 SN - 1432-1114 VL - 60 EP - Article number 2 PB - Springer CY - Berlin ER - TY - JOUR A1 - Valero, Daniel A1 - Viti, Nicolo A1 - Gualtieri, Carlo T1 - Numerical Simulation of Hydraulic Jumps. Part 1: Experimental Data for Modelling Performance Assessment JF - Water Y1 - 2019 U6 - http://dx.doi.org/10.3390/w11010036 SN - 2073-4441 VL - 11 IS - 1 SP - Art. Nr. 36 PB - MDPI CY - Basel ER - TY - JOUR A1 - Viti, Nicolo A1 - Valero, Daniel A1 - Gualtieri, Carlo T1 - Numerical Simulation of Hydraulic Jumps. Part 2: Recent Results and Future Outlook JF - Water Y1 - 2019 U6 - http://dx.doi.org/10.3390/w11010028 SN - 2073-4441 VL - 11 IS - 1 SP - Art. Nr. 28 ER - TY - JOUR A1 - Jochim, Haldor E. A1 - Menzel, Christoph J. T1 - Die Trassenbündelung als Planungsmethode nachhaltiger Verkehrspolitik JF - Der Eisenbahningenieur : EI Y1 - 2018 SN - 0013-2810 VL - 69 IS - 11 SP - 26 EP - 31 PB - DVV Media Group CY - Hamburg ER - TY - JOUR A1 - Reger, Vitali A1 - Kuhnhenne, Markus A1 - Hachul, Helmut A1 - Döring, Bernd A1 - Blanke, Tobias A1 - Göttsche, Joachim T1 - Plusenergiegebäude 2.0 in Stahlleichtbauweise JF - Stahlbau Y1 - 2019 U6 - http://dx.doi.org/10.1002/stab.201900034 SN - 1437-1049 (E-journal), 0038-9145 (print) VL - 88 IS - 6 SP - 522 EP - 528 PB - Ernst & Sohn CY - Berlin ER - TY - JOUR A1 - Valero, Daniel A1 - Chanson, Hubert A1 - Bung, Daniel B. T1 - Robust estimators for turbulence properties assessment Y1 - 2019 SP - 1 EP - 24 ER - TY - JOUR A1 - Klubert, Joachim A1 - Malecha, Hartmut A1 - Sparla, Peter T1 - Modernisierung der geodätischen Messtechnik der Urfttalsperre JF - Wasserwirtschaft T2 - Modernisation of the geodetic measurement technology of the Urft dam Y1 - 2018 SN - 0043-0978 N1 - gedruckt in der Bereichsbibliothek Bayernallee vorhanden VL - 108 IS - 10 SP - 14 EP - 18 PB - Springer Vieweg CY - Wiesbaden ER - TY - JOUR A1 - Valero, Daniel A1 - Chanson, Hubert A1 - Bung, Daniel B. T1 - Robust estimators for free surface turbulence characterization: A stepped spillway application JF - Flow Measurement and Instrumentation N2 - Robust estimators are parameters insensitive to the presence of outliers. However, they presume the shape of the variables’ probability density function. This study exemplifies the sensitivity of turbulent quantities to the use of classic and robust estimators and the presence of outliers in turbulent flow depth time series. A wide range of turbulence quantities was analysed based upon a stepped spillway case study, using flow depths sampled with Acoustic Displacement Meters as the flow variable of interest. The studied parameters include: the expected free surface level, the expected fluctuation intensity, the depth skewness, the autocorrelation timescales, the vertical velocity fluctuation intensity, the perturbations celerity and the one-dimensional free surface turbulence spectrum. Three levels of filtering were utilised prior to applying classic and robust estimators, showing that comparable robustness can be obtained either using classic estimators together with an intermediate filtering technique or using robust estimators instead, without any filtering technique. Y1 - 2020 U6 - http://dx.doi.org/10.1016/j.flowmeasinst.2020.101809 SN - 0955-5986 VL - 76 IS - Art. 101809 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Wolisz, Henryk A1 - Schütz, Thomas A1 - Blanke, Tobias A1 - Hagenkamp, Markus A1 - Kohrn, Markus A1 - Wesseling, Mark A1 - Müller, Dirk T1 - Cost optimal sizing of smart buildings' energy system components considering changing end-consumer electricity markets JF - Energy Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.energy.2017.06.025 VL - 137 SP - 715 EP - 728 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Gronsfeld, Richard A1 - Joachim, Klubert A1 - Malecha, Hartmut T1 - 3-D-Visualisierung von vorhandenen Staubauwerken zur holistischen Planung und Überwachung JF - Wasserwirtschaft Y1 - 2019 U6 - http://dx.doi.org/10.1007/s35147-019-0075-x SN - 2192-8762 N1 - gedruckt in der Bereichsbibliothek Bayernallee unter der Signatur 13 Z 218 vorhanden VL - 109 IS - 5 SP - 82 EP - 85 PB - Springer CY - Berlin ER - TY - JOUR A1 - Kuhnhenne, Markus A1 - Reger, Vitali A1 - Pyschny, Dominik A1 - Döring, Bernd T1 - Influence of airtightness of steel sandwich panel joints on heat losses JF - E3S Web of Conferences 12th Nordic Symposium on Building Physics (NSB 2020) N2 - Energy saving ordinances requires that buildings must be designed in such a way that the heat transfer surface including the joints is permanently air impermeable. The prefabricated roof and wall panels in lightweight steel constructions are airtight in the area of the steel covering layers. The sealing of the panel joints contributes to fulfil the comprehensive requirements for an airtight building envelope. To improve the airtightness of steel sandwich panels, additional sealing tapes can be installed in the panel joint. The influence of these sealing tapes was evaluated by measurements carried out by the RWTH Aachen University - Sustainable Metal Building Envelopes. Different installation situations were evaluated by carrying out airtightness tests for different joint distances. In addition, the influence on the heat transfer coefficient was also evaluated using the Finite Element Method (FEM). The combination of obtained air volume flow and transmission losses enables to create an "effective heat transfer coefficient" due to transmission and infiltration. This summarizes both effects in one value and is particularly helpful for approximate calculations on energy efficiency. Y1 - 2020 U6 - http://dx.doi.org/10.1051/e3sconf/202017205008 VL - 172 IS - Art. 05008 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Cheenakula, Dheeraja A1 - Hoffstadt, Kevin A1 - Krafft, Simone A1 - Reinecke, Diana A1 - Klose, Holger A1 - Kuperjans, Isabel A1 - Grömping, Markus T1 - Anaerobic digestion of algal–bacterial biomass of an Algal Turf Scrubber system JF - Biomass Conversion and Biorefinery N2 - This study investigated the anaerobic digestion of an algal–bacterial biofilm grown in artificial wastewater in an Algal Turf Scrubber (ATS). The ATS system was located in a greenhouse (50°54′19ʺN, 6°24′55ʺE, Germany) and was exposed to seasonal conditions during the experiment period. The methane (CH4) potential of untreated algal–bacterial biofilm (UAB) and thermally pretreated biofilm (PAB) using different microbial inocula was determined by anaerobic batch fermentation. Methane productivity of UAB differed significantly between microbial inocula of digested wastepaper, a mixture of manure and maize silage, anaerobic sewage sludge, and percolated green waste. UAB using sewage sludge as inoculum showed the highest methane productivity. The share of methane in biogas was dependent on inoculum. Using PAB, a strong positive impact on methane productivity was identified for the digested wastepaper (116.4%) and a mixture of manure and maize silage (107.4%) inocula. By contrast, the methane yield was significantly reduced for the digested anaerobic sewage sludge (50.6%) and percolated green waste (43.5%) inocula. To further evaluate the potential of algal–bacterial biofilm for biogas production in wastewater treatment and biogas plants in a circular bioeconomy, scale-up calculations were conducted. It was found that a 0.116 km2 ATS would be required in an average municipal wastewater treatment plant which can be viewed as problematic in terms of space consumption. However, a substantial amount of energy surplus (4.7–12.5 MWh a−1) can be gained through the addition of algal–bacterial biomass to the anaerobic digester of a municipal wastewater treatment plant. Wastewater treatment and subsequent energy production through algae show dominancy over conventional technologies. KW - Biogas KW - Methane KW - Algal Turf Scrubber KW - Algal–bacterial bioflm KW - Circular bioeconomy Y1 - 2022 U6 - http://dx.doi.org/10.1007/s13399-022-03236-z SN - 2190-6823 N1 - Corresponding author: Dheeraja Cheenakula VL - 13 SP - 15 Seiten PB - Springer CY - Berlin ER - TY - JOUR A1 - Reger, Vitali A1 - Kuhnhenne, Markus A1 - Ebbert, Thiemo A1 - Hachul, Helmut A1 - Blanke, Tobias A1 - Döring, Bernd T1 - Nutzung erneuerbarer Energien durch thermische Aktivierung von Komponenten aus Stahl JF - Stahlbau N2 - Die Versorgung von Neubauten soll möglichst weitgehend unabhängig von fossilen Energieträgern erfolgen. Erneuerbare Energien spielen dafür eine gewichtige Rolle. Eine gute Möglichkeit, erneuerbare Energien ohne viel zusätzlichen Aufwand nutzbar zu machen, ist, bereits vorhandenen Komponenten im Gebäude zusätzliche Funktionen zu geben. Hier kann bspw. die Fassade oder das Dach solarthermisch aktiviert oder durch Fotovoltaikmodule ergänzt werden. Auch Tiefgründungen können neben der statischen Funktion noch eine geothermische Funktion zur Aufnahme oder Abgabe von Wärme erhalten. Neben der Erzeugung bietet sich auch für die Verteilung der Wärme oder Kälte im Gebäude die Integration in Bauteile an. Hier kann bspw. der Boden durch eine Fußbodenheizung oder die Decke durch Deckenstrahlplatten aktiviert werden. Im Rahmen der Veröffentlichung wird auf die thermische Aktivierung von Stahlkomponenten eingegangen. Es wird eine Lösung vorgestellt, die vorgehängte hinterlüftete Stahlfassade (VHF) solarthermisch zu aktivieren. Außerdem werden zwei Möglichkeiten zur geothermischen Aktivierung von Tiefgründungen mittels Stahlpfählen gezeigt. Zuletzt wird ein System zur thermischen Aktivierung von Stahltrapezprofilen an der Decke erläutert, welches Wärme zuführen oder bei Bedarf abführen kann. Y1 - 2020 U6 - http://dx.doi.org/10.1002/stab.202000031 SN - 1437-1049 VL - 2020 IS - Volume 89, Issue 6512-519 SP - 512 EP - 519 PB - Ernst & Sohn CY - Berlin ER - TY - JOUR A1 - Blanke, Tobias A1 - Hagenkamp, Markus A1 - Döring, Bernd A1 - Göttsche, Joachim A1 - Reger, Vitali A1 - Kuhnhenne, Markus T1 - Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates JF - Geothermal Energy N2 - Previous studies optimized the dimensions of coaxial heat exchangers using constant mass fow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar fow types. In contrast, in this study, fow conditions in the circular ring are kept constant (a set of fxed Reynolds numbers) during optimization. This approach ensures fxed fow conditions and prevents inappropriately high or low mass fow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic efort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass fow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellström’s borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefcients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy diference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy fux and hydraulic efort. The Reynolds number in the circular ring is instead of the mass fow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54% of the outer pipe radius for laminar fow and 60% for turbulent fow scenarios. Net-exergetic optimization shows a predominant infuence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth’s thermal properties and the fow type. Conclusively, coaxial geothermal probes’ design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics. Y1 - 2021 U6 - http://dx.doi.org/10.1186/s40517-021-00201-3 SN - 2195-9706 N1 - Corresponding author: Tobias Blanke VL - 9 IS - Article number: 19 PB - Springer CY - Berlin ER - TY - JOUR A1 - Hagenkamp, Markus A1 - Blanke, Tobias A1 - Döring, Bernd T1 - Thermoelectric building temperature control: a potential assessment JF - International Journal of Energy and Environmental Engineering N2 - This study focuses on thermoelectric elements (TEE) as an alternative for room temperature control. TEE are semi-conductor devices that can provide heating and cooling via a heat pump effect without direct noise emissions and no refrigerant use. An efficiency evaluation of the optimal operating mode is carried out for different numbers of TEE, ambient temperatures, and heating loads. The influence of an additional heat recovery unit on system efficiency and an unevenly distributed heating demand are examined. The results show that TEE can provide heat at a coefficient of performance (COP) greater than one especially for small heating demands and high ambient temperatures. The efficiency increases with the number of elements in the system and is subject to economies of scale. The best COP exceeds six at optimal operating conditions. An additional heat recovery unit proves beneficial for low ambient temperatures and systems with few TEE. It makes COPs above one possible at ambient temperatures below 0 ∘C. The effect increases efficiency by maximal 0.81 (from 1.90 to 2.71) at ambient temperature 5 K below room temperature and heating demand Q˙h=100W but is subject to diseconomies of scale. Thermoelectric technology is a valuable option for electricity-based heat supply and can provide cooling and ventilation functions. A careful system design as well as an additional heat recovery unit significantly benefits the performance. This makes TEE superior to direct current heating systems and competitive to heat pumps for small scale applications with focus on avoiding noise and harmful refrigerants. Y1 - 2021 U6 - http://dx.doi.org/10.1007/s40095-021-00424-x N1 - Corresponding author: Markus Hagenkamp VL - 13 SP - 241 EP - 254 PB - Springer CY - Berlin ER - TY - JOUR A1 - Blanke, Tobias A1 - Reger, Vitali A1 - Döring, Bernd A1 - Göttsche, Joachim A1 - Kuhnhenne, Markus T1 - Koaxiale Stahlenergiepfähle JF - Stahlbau N2 - 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. Y1 - 2021 VL - 90. 2021 IS - 6 SP - 417 EP - 424 PB - Wiley CY - Weinheim ER -