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  - https://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  - Biener, Ernst
A1  - Wemhoff, T.
A1  - Bethke, H.
T1  - Stability and settlement problems based on the example of the Blockland landfill in Bremen
JF  - Sardinia 95 : Fifth International Landfill Symposium ; (2 - 6 October 1995, S. Margheritadi Pula - Cagliari, Sardinia, Italy) ; proceedings / coord.: Thomas H. Christensen ... - Bd. 2 : Siting, lining, drainage & landfill mechanics
Y1  - 1995
N1  - International Landfill Symposium <5, 1995, Santa Margherita, Pula>
SP  - 843
EP  - 853
PB  - CISA, Environmental Sanitary Engineering Centre
CY  - Cagliari
ER  - 
TY  - JOUR
A1  - Biener, Ernst
A1  - Sasse, T.
A1  - Wernhoff, T.
T1  - Using harbour dredged material for combination sealing of the former Bockhorner Weg disposal site in Bremen, Germany
JF  - Proceedings of the International Harbour Congress. 13 (2003)
Y1  - 2003
N1  - International Harbour Congress <13, 2003, Antwerpen>
SP  - 101
EP  - 109
ER  - 
TY  - JOUR
A1  - Biener, Ernst
A1  - Sasse, T.
A1  - Konertz, K.
T1  - Preparation of mineral sealing materials for landfills by different processing technologies / Sasse, T. ; Biener, E. ; Konertz, K.
JF  - Sardinia 93 : Fourth International Landfill Symposium "Barrier systems, environmental aspects, upgrading and remediation, siting, monofills, effects of waste pretreatment, landfilling in developing countries" ; 11 - 15 October 1993, S. Margherita di Pula (Cagliari), Sardinia, Italy ; proceedings / coord. by Thomas H. Christensen ... - Bd. 1
Y1  - 1993
N1  - International Landfill Symposium <4, 1993, Santa Margherita, Pula>
SP  - 275
EP  - 283
PB  - CISA, Environmental Sanitary Engineering Centre
CY  - Cagliari
ER  - 
TY  - JOUR
A1  - Biener, Ernst
A1  - Sasse, T.
A1  - Bökers, H.
T1  - Preliminary or final capping of sanitary landfills? : Technical and economical aspects
JF  - Sardinia 99 : proceedings / Seventh International Waste Management and Landfill Symposium, [4 - 8 October 1999, S. Margherita di Pula, Cagliari, Sardinia, Italy]. Ed.: Thomas H. Christensen. -  Bd. 3 : Barriers, waste mechanics and landfill design
Y1  - 1999
N1  - International Waste Management and Landfill Symposium <7, 1999, Cagliari>
SP  - 287
EP  - 294
PB  - CISA, Environmental Sanitary Engineering Centre
CY  - Cagliari
ER  - 
TY  - JOUR
A1  - Biener, Ernst
A1  - Sasse, T.
A1  - Arnold, J.
A1  - Woltering, S.
T1  - New treatment of harbour sludge in Bremen and Bremerhaven  /  E. Biener ; T. Sasse ; J. Arnold ; S. Woltering ; N. Binder
JF  - Characterisation and treatment of sediments : Antwerpen, Belgium, September 15 - 17, 1999 ; [preceded by 12th International Harbour Congress] ; proceedings / CATS 4. Ed.: G. De Schutter. Organized by: Technologisch Instituut, Koninklijke Vlaamse Ingenieursvereniging
Y1  - 1999
SN  - 9076019118
N1  - CATS <4, 1999, Anvers>
SP  - 115
EP  - 122
PB  - Technolog. Inst.
CY  - Anvers
ER  - 
TY  - JOUR
A1  - Biener, Ernst
A1  - Sasse, T.
T1  - Construction and rehabilitation of landfill shafts
JF  - Sardinia 93 : Fourth International Landfill Symposium "Barrier systems, environmental aspects, upgrading and remediation, siting, monofills, effects of waste pretreatment, landfilling in developing countries" ; 11 - 15 October 1993, S. Margherita di Pula (Cagliari), Sardinia, Italy ; proceedings / coord. by Thomas H. Christensen ... - Bd. 1
Y1  - 1993
N1  - International Landfill Symposium <4, 1993, Santa Margherita, Pula>
SP  - 451
EP  - 460
PB  - CISA, Environmental Sanitary Engineering Centre
CY  - Cagliari
ER  - 
TY  - JOUR
A1  - Biener, Ernst
A1  - Sasse, T.
T1  - Construction of composite lining systems under unfavourable weather conditions
JF  - Landfilling of waste: barriers / ed. by T. H. Christensen; R. Cossu; R. Stegmann. - 1. Aufl.
Y1  - 1994
SN  - 0419159908
SP  - 183
EP  - 200
PB  - Spon
CY  - London [u.a.]
ER  - 
TY  - JOUR
A1  - Biener, Ernst
A1  - Sasse, T.
T1  - Quality improvements in the construction of multilayer covers
JF  - Géologie et confinement des déchets toxiques : actes du symposium international, 8 - 11 juin 1993 / GEOCONFINE 93, Montpellier, France. Réd. Marcel Arnould
Y1  - 1993
SN  - 90-5410-330-2
N1  - Geoconfine <1993, Montpellier> ; Paralellt.: Geology and confinement of toxic wastes
SP  - 309
EP  - 312
PB  - Balkema
CY  - Rotterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Biener, Ernst
A1  - Sasse, T.
T1  - Experience with new techniques in slurry cutoff wall construction
JF  - ISWA 88, proceedings of the 5th International Solid Wastes Conference : September 11 - 16th, 1988, Copenhagen, Denmark / ed. by Lizzi Andersen ... - Vol. 1 : Oral presentations
Y1  - 1988
SN  - 0-12-058451-4
N1  - International Solid Wastes Conference <5, 1988, København> ; International Solid Wastes and Public Cleansing Association
SP  - 41
EP  - 46
PB  - Acad. Press
CY  - London [u.a.]
ER  -