@article{BlankeHagenkampDoeringetal.2021,
  author    = {Blanke, Tobias and Hagenkamp, Markus and D{\"o}ring, Bernd and G{\"o}ttsche, Joachim and Reger, Vitali and Kuhnhenne, Markus},
  title     = {Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates},
  series = {Geothermal Energy},
  volume    = {9},
  journal   = {Geothermal Energy},
  number    = {Article number: 19},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {2195-9706},
  doi       = {10.1186/s40517-021-00201-3},
  pages     = {23 Seiten},
  year      = {2021},
  abstract  = {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 Hellstr{\"o}m'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.},
  language  = {en}
}
@article{CheenakulaHoffstadtKrafftetal.2022,
  author    = {Cheenakula, Dheeraja and Hoffstadt, Kevin and Krafft, Simone and Reinecke, Diana and Klose, Holger and Kuperjans, Isabel and Gr{\"o}mping, Markus},
  title     = {Anaerobic digestion of algal-bacterial biomass of an Algal Turf Scrubber system},
  series = {Biomass Conversion and Biorefinery},
  volume    = {13},
  journal   = {Biomass Conversion and Biorefinery},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {2190-6823},
  doi       = {10.1007/s13399-022-03236-z},
  pages     = {15 Seiten},
  year      = {2022},
  abstract  = {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.},
  language  = {en}
}
@inproceedings{BuehlerLeandroBungetal.2015,
  author    = {B{\"u}hler, P. and Leandro, J. and Bung, Daniel Bernhard and Lopes, P. and Carvalho, R.},
  title     = {Measuring void fraction of a stepped spillway with non-intrusive methods using different image resolutions},
  series = {2nd International Workshop on Hydraulic Structures : Data Validation : Coimbra, Portugal, 8-9 May 2015},
  booktitle = {2nd International Workshop on Hydraulic Structures : Data Validation : Coimbra, Portugal, 8-9 May 2015},
  organization    = {International Workshop on Hydraulic Structures : Data Validation <2, 2015, Coimbra>},
  pages     = {1 -- 8},
  year      = {2015},
  language  = {en}
}
@inproceedings{WolfUlbrich2007,
  author    = {Wolf, Martin R. and Ulbrich, Daniel},
  title     = {Decision-Support-System kokas zur Sanierungsplanung und Strategieentwicklung},
  year      = {2007},
  abstract  = {Dr.-Ing. Martin Wolf ; Dipl.-Kaufm. Daniel Ulbrich , Dr. Pecher und Partner Ingenieurgesellschaft mbH, M{\"u}nchen. 31 S. (S. 139-168). Beitrag zum 1. Aachener Softwaretag in der Wasserwirtschaft < 1, 2007, Aachen>. Zusammenfasung [der Autoren] Die {\"o}ffentlichen Kanalnetze Deutschlands stellen mit einem Wert von rd. 330 Mrd. € ein enormes Anlageverm{\"o}gen dar. Auf Grund des oft schlechten Zustandes und geringer Ausgaben zur Instandhaltung und Erneuerung ist zu erwarten, dass durch die gegenw{\"a}rtige Sanierungspraxis eher ein Substanzwertverzehr des Kanalnetzes als ein Substanzwerterhalt im Sinne des Generationenvertrages erzielt wird. F{\"u}r einen nachhaltigen Betrieb und Erhalt der Kanalnetze sind deshalb Sanierungsstrategien erforderlich, die neben den technischen und gesetzlichen Anforderungen auch den mittel- und langfristigen Substanzwertverlauf ber{\"u}cksichtigen. Dieser wird beeinflusst vom erforderlichen oder durchgef{\"u}hrten Sanierungsumfang, Art und Zusammensetzung der ausgew{\"a}hlten Maßnahmen sowie der zeitlichen Abfolge der Sanierungsmaßnahmen. Erheblichen Einfluss auf den Substanzwertverlauf hat zudem die Ber{\"u}cksichtigung der hydraulischen Verh{\"a}ltnisse sowie der optisch nicht sichtbaren Undichtheiten. Entsprechend ist es erforderlich, die tats{\"a}chlich vorhandenen Defizite zu ermitteln und die Sanierungsmaßnahmen sowie eine Strategie zur Umsetzung zu erarbeiten. Da sich gezeigt hat, dass alleine die Einhaltung der technischen und gesetzlichen Anforderung f{\"u}r einen Substanzwerterhalt nicht ausreicht, muss die geplante Strategie im Dr.-Ing. Martin Wolf 139 von 170 Decision-Support-System kokas zur Sanierungsplanung und Strategieentwicklung 1. Aachener Softwaretag in der Wasserwirtschaft Hinblick auf die nachhaltige Wertentwicklung {\"u}berpr{\"u}ft und ggf. Anpassungen vorgenommen werden. Kurzfristig erzielte Einsparungen durch reduzierten Schadensumfang oder einseitige Maßnahmenwahl erm{\"o}glichen zwar im g{\"u}nstigsten Fall, die Anforderungen einzuhalten, gehen jedoch zwangsl{\"a}ufig zu Lasten des Substanzwertes und f{\"u}hren mittel- und langfristig zu einer Versch{\"a}rfung der Kosten- und Geb{\"u}hrensituation. Der monet{\"a}re, am konkreten Sanierungsaufwand orientierte Substanzwertansatz erm{\"o}glicht dabei, technische und kaufm{\"a}nnische Gesichtspunkte praxisnah zu verkn{\"u}pfen und den bestm{\"o}glichen Ausgleich zwischen den gegenl{\"a}ufigen Zielen Substanzwerterhalt und Geb{\"u}hrenkonstanz zu finden.},
  subject      = {Kanalisation},
  language  = {de}
}
@article{CheenakulaPaulsenOttetal.2023,
  author    = {Cheenakula, Dheeraja and Paulsen, Svea and Ott, Fabian and Gr{\"o}mping, Markus},
  title     = {Operational window of a deammonifying sludge for mainstream application in a municipal wastewater treatment plant},
  series = {Water and Environment Journal},
  volume    = {38},
  journal   = {Water and Environment Journal},
  number    = {1},
  publisher = {Wiley},
  address   = {Chichester},
  issn      = {1747-6593},
  doi       = {10.1111/wej.12898},
  pages     = {59 -- 70},
  year      = {2023},
  abstract  = {The present work aimed to study the mainstream feasibility of the deammonifying sludge of side stream of municipal wastewater treatment plant (MWWTP) in Kaster, Germany. For this purpose, the deammonifying sludge available at the side stream was investigated for nitrogen (N) removal with respect to the operational factors temperature (15-30°C), pH value (6.0-8.0) and chemical oxygen demand (COD)/N ratio (≤1.5-6.0). The highest and lowest N-removal rates of 0.13 and 0.045 kg/(m³ d) are achieved at 30 and 15°C, respectively. Different conditions of pH and COD/N ratios in the SBRs of Partial nitritation/anammox (PN/A) significantly influenced both the metabolic processes and associated N-removal rates. The scientific insights gained from the current work signifies the possibility of mainstream PN/A at WWTPs. The current study forms a solid basis of operational window for the upcoming semi-technical trails to be conducted prior to the full-scale mainstream PN/A at WWTP Kaster and WWTPs globally.},
  language  = {en}
}
@inproceedings{Bung2014,
  author    = {Bung, Daniel Bernhard},
  title     = {Observations on non-aerated flow and air entrainment on moderately sloped stepped spillways},
  series = {7th Chinese-German Joint Symposium on Hydraulic and Ocean Engineering : 8. - 12. Sept. 2014, Hannover},
  booktitle = {7th Chinese-German Joint Symposium on Hydraulic and Ocean Engineering : 8. - 12. Sept. 2014, Hannover},
  organization    = {Chinese-German Joint Symposium on Hydraulic and Ocean Engineering <7, 2014, Hannover>},
  pages     = {1 -- 8},
  year      = {2014},
  language  = {en}
}
@inproceedings{UibelBlass2010,
  author    = {Uibel, Thomas and Blaß, Hans Joachim},
  title     = {A new method to determine suitable spacings and distances for self-tapping screws},
  series = {Meeting ... / International Council for Research and Innovation in Building and Construction, Working Commission W18 - Timber Structures},
  volume    = {43},
  booktitle = {Meeting ... / International Council for Research and Innovation in Building and Construction, Working Commission W18 - Timber Structures},
  publisher = {Lehrstuhl f{\"u}r Ingenieurholzbau und Baukonstruktionen},
  address   = {Karlsruhe},
  issn      = {1864-1784},
  year      = {2010},
  abstract  = {The determination of spacing, edge and end distance requirements for self-tapping screws requires numerous and comprehensive insertion tests. Yet the results of such tests cannot be transferred to other types of screws or even to screws of different diameter because of differences in shape or geometry. To reduce the effort of insertion tests a new method was developed which allows the estimation of required spacings, distances and timber thickness.},
  language  = {en}
}