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Abstract District heating dynamic models arise as an alternative approach to in-situ experimental investigations. The main advantage of dynamic modeling and simulation is the possibility to avoid technical and operational risks that might occur during in-situ experimental investigations (e.g. heat demand is not met, damages in the energy systems etc.). Within this study, the authors present two models for an existing district heating system in Cottbus, Germany. One model is developed using the tool EBSILON Professional, while the other one is developed using the Simscape toolbox for physical modeling in Matlab/Simulink. The models were experimentally validated against measured data from the considered district heating system. The results show that the Simscape model has a better fit and better response than the EBSILON model. Yet, some discrepancies were found between the measured and the simulated data and, therefore, the uncertainties of the models were addressed. A comparative study between both tools is presented. The EBSILON models permit only unidirectional flow, whereas the Simscape toolbox permits reverse flow. Nevertheless, the EBSILON model outperforms the Simscape model in computation time. In addition, this study presents an approach for dynamic thermo-hydraulic modeling of district heating networks. This approach is utilized to examine the role of district heating networks as heat storage as an optimization configuration. The numerical results show less start-ups for additional heat sources. Yet, higher heat losses from the network are observed due to the installation of unburied pipelines.

Abstract The reliability of nuclear structures relates directly to the reliability of mechanical and electronic systems. Nuclear structures may be viewed as part of operational system as well as part of standby safety system. Except for proof loading, most of the load types, seen by nuclear structures, such as containments, primary piping, etc. during their design life, are random in time and space. Structural resistances, governed mainly by the respective material properties show also random characteristics. Methods of structural reliability, as discussed here, provide the means to process rationally the available information. Hence, they are an indispensable tool within the frame work of probabilistic risk analyses (PRA's). The probabilistic analysis is exemplified by determining the reliability of a containment structure sited in an area with strong seismicity.

Future automotive technologies become more and more autonomous and connected. This trend requires a rethinking of validation processes due to the amount of test kilometers needed. To be able to test automated and connected functions in many different traffic scenarios, virtual and mixed real-virtual prototypes will be used. Moreover, due to the complexity of such systems, cross-company cooperation is increasing and demands for common prototypes. Spatially distributed prototypes simplify and enhance cross-company collaboration due to faster provisioning of models and better IP protection. However, the setup of such prototypes is very time consuming due to the high integration effort. Here it is shown that the integration effort of spatially distributed prototypes can be massively reduced by using the Distributed Co-Simulation Protocol (DCP). A demonstrator consisting of a small scale test bed located in Graz and a co-simulation containing Bosch driving functions located in Renningen is presented. The demonstrated integration workflow as well as an analysis of the communication challenges of the coupling can be transferred to any other coupling of this kind.

Energy supply is a global hot topic. The social and political pressure forces a higher percentage of energy supplied by renewable resources. The production of renewable energy in form of biomethane can be increased by co-substrates such as municipal biowaste. However, a demand-driven energy production or its storage needs optimisation, the option to store the substrate with its inherent energy is investigated in this study. The calorific content of biowaste was found unchanged after 45 d of storage (19.9±0.19 kJ g(-1) total solids), and the methane yield obtained from stored biowaste was comparable to fresh biowaste or even higher (approx. 400 m(3) Mg(-1) volatile solids). Our results show that the storage supports the hydrolysis of the co-substrate via acidification and production of volatile fatty acids. The data indicate that storage of biowaste is an efficient way to produce bioenergy on demand. This could in strengthen the role of biomethane plants for electricity supply the future.

AbstractThe international building sector plays an important role on energy policy and reduction of CO2 emissions. The focus of energy conservation has started from building level and nowadays expands to district, city, region or national level. In this study, an overview, performed within the European project Sinfonia for preparation of a new district tool with focus on energy conservation, will be presented about existing district tools. Several aspects of the tools were included in the overview, such as focus, aim, analytical approach, methodology, geographical coverage, required input data, commercial/freeware, source code, language, tool status, organization/project developing the tool, and web link. The main components of energy district tools such as 3D geographical data, data for building features and properties, and simulation methods were also addressed.Additionally, the issue of appropriate boundary conditions on urban energy analysis, such as user behaviour, will be discussed. A simulation study of a dwelling in various energy standards including different occupant scenarios was performed, and as a result, a formula was developed to estimate an equivalent heating reference temperature as a function of building envelope, living area, and outdoor temperature. Thus, the estimated equivalent heating reference temperature can be used as input in district energy simulations, instead of a constant set point value independent of the building.The present study can serve as a basis for new or further development of tools trying to cover the gap and the limits of the existing ones.

Abstract In this work we present a simulation of performance of curved thin-film modules for building and product integrated photovoltaic applications. Flexibility of design and possibility of achieving irregular shapes is important feature in these markets. The photovoltaic module model presented in this work is based on a coupled two-step model. The first 1D model describes the technology and outputs device current density in dependence of voltage, temperature, illumination, etc. The second 3D model uses this data as one of its inputs, and describes size, shape and interconnection of the individual cells within the curved flexible module. In this way power production of such photovoltaic system can be assessed in reasonable time and computing resources. Two study cases are presented: a dome shaped solar street lamp and a conic shaped active rooftop shading for a skylight.

With regard to renewable sources of energy, bioconversion of lignocellulosic biomass has long been recognized as a desirable endeavor. However, the highly heterogeneous structure of lignocellulose restricts the exploitation of its promising potential in biogas plants. Hence, effective pre-treatment methods are decisive prerequisites to overcome these challenges in order to improve the utilization ratio of (ligno) cellulosic substrates during fermentation. In the present study, the application of Trichoderma viride in an aerobic upstream process prior to anaerobic digestion led up to a threefold increase in the yield of methane and total gas in a lab-scale investigation. Due to its highly efficient cellulolytic activities, T. viride seemed to be responsible for an improved nutrient availability that positively influenced the anaerobic microbiocenosis. Aerobic pre-treatment of organic matter with T. viride is therefore a promising solution to achieve higher methane yields and degradation performances without any additional energy demand, nor undesired by-product inhibition.