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AbstractDer anaerobe Abbau von organischen Substraten zu Kohlendioxid und Methan ist ein mikrobiell katalysierter Prozess. Die einstufige Biogasgewinnung ist in der Landwirtschaft und in der Klärschlammaufbereitung weit verbreitet. Es findet eine Grobzerkleinerung statt, die nicht der Optimierung der Verweilzeitverkürzung dient, sondern das Verstopfen der Ventile und Pumpen verhindern soll. Ziel war es, den Einfluss der Partikelgröße auf den Biogasertrag festzustellen und die Zerkleinerung zu optimieren. Mit feinstzerkleinerten Trebersuspensionen als Substrat für die anaerobe Fermentation konnte bei stabilen Prozessbedingungen eine kürzere hydraulischer Verweilzeit, ein höherer Abbaugrad und ein höherer Methangehalt des Biogases erreicht werden.

The gas velocity interval for initiating gas fluidization of binary mixtures of Geldart type B particles has been thoroughly investigated experimentally and theoretically by Formisani et al.[2–6] The same approach has now been applied in our laboratory to liquid fluidization of binary macro‐solids. Experimental results for water fluidization in a 190.5 mm diameter column of initially well mixed packed beds, consisting of different volumetric fractions of 1.91 mm and 4.54 mm glass spheres of density 2510 kg/m3, are well predicted by the methods of Formisani et al., whether the equations are based on random‐dense voidages as practiced by that group, or based on random‐loose voidages as commonly used for monocomponent solids.

AbstractWith increasing digitization, new opportunities emerge concerning the availability and use of data in the energy sector. A comprehensive literature review shows an abundance in available unsupervised clustering algorithms as well as internal, relative and external cluster validation indices (cvi) to evaluate the results. Yet, the comparison of different clustering results on the same dataset, executed with different algorithms and a specific practical goal in mind still proves scientifically challenging. A large variety of cvi are described and consolidated in commonly used composite indices (e.g. Davies-Bouldin-Index, silhouette-Index, Dunn-Index). Previous works show the challenges surrounding these composite indices since they serve a generalized cluster quality evaluation. However, this does not suit individual clustering goals in many cases. The presented paper introduces the current state of science, existing cluster validation indices and proposes a practical method to combine them to an individual composite index, using Multi Criteria Decision Analysis (mcda). The methodology is applied on two energy economic use cases for clustering load profiles of bidirectional electric vehicles and municipalities.

“Community energy” is a highly contested issue not only in the German energy transition governance but also in the recent legislative procedure to recast energy market legislation within the EU’s “Winter Package”. This paper analyses the effects of the privileges for “community energy actors” in the German auction scheme for on-shore wind energy. Those privileges aim to guarantee a level playing field for small actors and to enhance societal acceptance. The results of the first rounds of auctions did not merely reveal an acceptable level of losses due to recognized trade-offs between policy objectives. Instead, the results indicate a complete failure regarding all three objectives of the revised support scheme for renewables—controlled renewable energy expansion, actor plurality and cost efficiency. The paper discusses whether the policy motivations translate appropriately into legislation. It suggests differentiating clearly the economic risks for small actors from the added value that is attributed to community energy actors. De-coupling these—often mixed—motives behind the demands for actor plurality unveils policy approaches that more adequately fit with these distinct motives. The paper finally proposes rather to integrate the politically desired values into the bid evaluation criteria instead of granting privileges to specific actors that are assumed to provide these values.

This study shows that enhanced radiobiological effectiveness (RBE) values can be generated focusing low linear energy transfer (LET) radiation and thus changing the microdose distribution. 20 MeV protons (LET = 2.65 keV µm(-1)) are focused to submicrometer diameter at the ion microprobe superconducting nanoprobe for applied nuclear (Kern) physics experiments of the Munich tandem accelerator. The RBE values, as determined by measuring micronuclei (RBE(MN) = 1.48 ± 0.07) and dicentrics (RBE(D) = 1.92 ± 0.15), in human-hamster hybrid (A(L)) cells are significantly higher when 117 protons were focused to a submicrometer irradiation field within a 5.4 × 5.4 µm(2) matrix compared to quasi homogeneous in a 1 × 1 µm(2) matrix applied protons (RBE(MN) = 1.28 ± 0.07; RBE(D) = 1.41 ± 0.14) at the same average dose of 1.7 Gy. The RBE values are normalized to standard 70 kV (dicentrics) or 200 kV (micronuclei) x-ray irradiation. The 117 protons applied per point deposit the same amount of energy like a (12)C ion with 55 MeV total energy (4.48 MeV u(-1)). The enhancements are about half of that obtained for (12)C ions (RBE(MN) = 2.20 ± 0.06 and RBE(D) = 3.21 ± 0.10) and they are attributed to intertrack interactions of the induced damages. The measured RBE values show differences from predictions of the local effect model (LEM III) that is used to calculate RBE values for irradiation plans to treat tumors with high LET particles.

Corporate social responsibility as a management concept is growing more and more important also for project companies. The task of project management is to identify relevant ecological systems, to recognize the internal and external dimension of social responsibility, and to test existing standards of Corporate Social Responsibility for their applicability in projects. The special benefit of CSR in projects is to set-up values such as integrity, credibility and reputation. For successful implementation of CSR activities, it is essential to align the commitment of the project organization to the own business operations and own goals.

Abstract From a two-phase model for an adiabatic packed bed through which a gas is flowing, a one-phase model is derived without assuming that the solid and gas temperatures are equal. By means of the derivation, a relationship between the axial effective thermal conductivity in the one-phase model and the heat transfer coefficient in the two-phase model is obtained. The validity of this relationship is confirmed using the experimental results of other authors. These results can also be applied to fixed bed chemical reactors if the reaction takes place in or on the surface of the catalyst. Essential to the derivation is the assumption that the thermal capacity of the gas phase can be neglected. For a fluid where this assumption is not valid, a separate derivation, whose assumptions are more restrictive, is presented in the appendix.

Abstract Thermal-hydraulic phenomena in the hot leg of a pressurized water reactor during the small break loss-of-coolant accident (SBLOCA) are simulated and studied in this paper. They include the single-phase flow dynamics, the cocurrent stratified flow during the natural circulation conditions, and the countercurrent stratified flow during the reflux condensation conditions. Satisfactory results were obtained from the computations in comparison with the data from the German Upper Plenum Test Facility. It is revealed that the fluid flow exhibits strong multi-dimensional effects, i.e. an appreciable acceleration and deceleration along different regions of the hot leg, and a four-vortex secondary flow structure in the cross-section of the bend region. Cocurrent stratified flow under the natural circulation conditions is successfully simulated, presenting two different water transport mechanisms. Under the reflux condensation conditions, different countercurrent flow structures are found under the conditions away from and with the countercurrent flow limit.