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 - 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 - Valero, D. A1 - Bung, Daniel B. A1 - Crookston, B. M. T1 - Closure to “Energy Dissipation of a Type III Basin under Design and Adverse Conditions for Stepped and Smooth Spillways” JF - Journal of Hydraulic Engineering Y1 - 2019 U6 - http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0001669 VL - 146 IS - 2 PB - ASCE CY - Reston, Va. ER - TY - JOUR A1 - Kerres, Karsten A1 - Gredigk-Hoffmann, Sylvia A1 - Jathe, Rüdiger A1 - Orlik, Stefan A1 - Sariyildiz, Mustafa A1 - Schmidt, Torsten A1 - Sympher, Klaus-Jochen A1 - Uhlenbroch, Adrian T1 - Future approaches for sewer system condition assessment JF - Water Practice & Technology N2 - Different analytical approaches exist to describe the structural substance or wear reserve of sewer systems. The aim is to convert engineering assessments of often complex defect patterns into computational algorithms and determine a substance class for a sewer section or manhole. This analytically determined information is essential for strategic rehabilitation planning processes up to network level, as it corresponds to the most appropriate rehabilitation type and can thus provide decision-making support. Current calculation methods differ clearly from each other in parts, so that substance classes determined by the different approaches are only partially comparable with each other. The objective of the German R&D cooperation project ‘SubKanS’ is to develop a methodology for classifying the specific defect patterns resulting from the interaction of all the individual defects, and their severities and locations. The methodology takes into account the structural substance of sewer sections and manholes, based on real data and theoretical considerations analogous to the condition classification of individual defects. The result is a catalogue of defect patterns and characteristics, as well as associated structural substance classifications of sewer systems (substance classes). The methodology for sewer system substance classification is developed so that the classification of individual defects can be transferred into a substance class of the sewer section or manhole, eventually taking into account further information (e.g. pipe material, nominal diameter, etc.). The result is a validated methodology for automated sewer system substance classification. Y1 - 2020 U6 - http://dx.doi.org/10.2166/wpt.2020.027 SN - 1751-231X IS - 15 (2) SP - 386 EP - 393 PB - IWA Publishing CY - London ER - TY - JOUR A1 - Bung, Daniel B. A1 - Crookston, Brian M. A1 - Valero, Daniel T1 - Turbulent free-surface monitoring with an RGB-D sensor: the hydraulic jump case JF - Journal of Hydraulic Research Y1 - 2020 U6 - http://dx.doi.org/10.1080/00221686.2020.1844810 SN - 1814-2079 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Erpicum, Sebastien A1 - Crookston, Brian M. A1 - Bombardelli, Fabian A1 - Bung, Daniel B. A1 - Felder, Stefan A1 - Mulligan, Sean A1 - Oertel, Mario A1 - Palermo, Michele T1 - Hydraulic structures engineering: An evolving science in a changing world JF - Wires Water Y1 - 2021 U6 - http://dx.doi.org/10.1002/wat2.1505 SN - 2049-1948 VL - 8 IS - 2 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Valero, Daniel A1 - Schalko, Isabella A1 - Friedrich, Heide A1 - Abad, Jorge D. A1 - Bung, Daniel B. A1 - Donchyts, Gennadii A1 - Felder, Stefan A1 - Ferreira, Rui M. L. A1 - Hohermuth, Benjamin A1 - Kramer, Matthias A1 - Li, Danxun A1 - Mendes, Luis A1 - Moreno-Rodenas, Antonio A1 - Nones, Michael A1 - Paron, Paolo A1 - Ruiz-Villanueva, Virginia A1 - Wang, Ruo-Qian A1 - Franca, Mario J. T1 - Pathways towards democratization of hydro-environment observations and data JF - Iahr White Paper Series Y1 - 2021 IS - 1 SP - 1 EP - 9 PB - International Association for Hydro-Environment Engineering and Research (IAHR) ER - TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. A1 - Erpicum, Sebastien A1 - Peltier, Yann A1 - Dewals, Benjamin T1 - Unsteady shallow meandering flows in rectangular reservoirs: a modal analysis of URANS modelling JF - Journal of Hydro-environment Research N2 - Shallow flows are common in natural and human-made environments. Even for simple rectangular shallow reservoirs, recent laboratory experiments show that the developing flow fields are particularly complex, involving large-scale turbulent structures. For specific combinations of reservoir size and hydraulic conditions, a meandering jet can be observed. While some aspects of this pseudo-2D flow pattern can be reproduced using a 2D numerical model, new 3D simulations, based on the unsteady Reynolds-Averaged Navier-Stokes equations, show consistent advantages as presented herein. A Proper Orthogonal Decomposition was used to characterize the four most energetic modes of the meandering jet at the free surface level, allowing comparison against experimental data and 2D (depth-averaged) numerical results. Three different isotropic eddy viscosity models (RNG k-ε, k-ε, k-ω) were tested. The 3D models accurately predicted the frequency of the modes, whereas the amplitudes of the modes and associated energy were damped for the friction-dominant cases and augmented for non-frictional ones. The performance of the three turbulence models remained essentially similar, with slightly better predictions by RNG k-ε model in the case with the highest Reynolds number. Finally, the Q-criterion was used to identify vortices and study their dynamics, assisting on the identification of the differences between: i) the three-dimensional phenomenon (here reproduced), ii) its two-dimensional footprint in the free surface (experimental observations) and iii) the depth-averaged case (represented by 2D models). KW - coherent structures KW - hydraulic modelling KW - model performance KW - Proper Orthogonal Decomposition KW - Q-criterion Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.jher.2022.03.002 SN - 1570-6443 IS - In Press PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - von Häfen, Hajo A1 - Krautwald, Clemens A1 - Stolle, Jacob A1 - Bung, Daniel Bernhard A1 - Goseberg, Nils T1 - Overland flow of broken solitary waves over a two-dimensional coastal plane JF - Coastal Engineering N2 - Landslides, rock falls or related subaerial and subaqueous mass slides can generate devastating impulse waves in adjacent waterbodies. Such waves can occur in lakes and fjords, or due to glacier calving in bays or at steep ocean coastlines. Infrastructure and residential houses along coastlines of those waterbodies are often situated on low elevation terrain, and are potentially at risk from inundation. Impulse waves, running up a uniform slope and generating an overland flow over an initially dry adjacent horizontal plane, represent a frequently found scenario, which needs to be better understood for disaster planning and mitigation. This study presents a novel set of large-scale flume test focusing on solitary waves propagating over a 1:14.5 slope and breaking onto a horizontal section. Examining the characteristics of overland flow, this study gives, for the first time, insight into the fundamental process of overland flow of a broken solitary wave: its shape and celerity, as well as its momentum when wave breaking has taken place beforehand. KW - Landslide tsunamis KW - Hazard assessment KW - Large scale tests KW - Overland flow KW - Solitary waves Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.coastaleng.2022.104125 SN - 1872-7379 VL - 175 IS - August PB - Elsevier CY - Amsterdam ER -