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Browsing Scopus by Department "Fraunhofer Institut für Mikrostruktur von Werkstoffen und Systemen IMWS"
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PublicationA consequential approach to life cycle sustainability assessment with an agent-based model to determine the potential contribution of chemical recycling to UN Sustainable Development Goals( 2023)
;Voss, Raoul Lukas ;Lee, R.P.Fröhling, M.Chemical recycling (CR) could support a circular approach for municipal solid waste (MSW) treatment. In promoting the recirculation of recyclable carbon-containing waste as secondary feedstock for chemical production, it could contribute to resource conservation, emissions reduction, and supply security. To evaluate CR's contribution to the transition from a linear to a circular carbon economy - and correspondingly to the achievement of environmental, economic, and social sustainability as indicated in the UN Sustainable Development Goals (UN-SDGs) - this study builds on extant literature of life cycle sustainability assessment (LCSA) to investigate consequential environmental, economic, and social CR impacts. Specifically, an integrated approach whereby process-based life cycle assessment, techno-economic analysis, and social indicators are linked in the framework of an agent-based model is developed to investigate sustainability consequences of CR via gasification of residual MSW in Germany. Results suggest that CR contributes to reducing climate change and to addressing terrestrial acidification and fossil resource scarcity. However, its deployment will be associated with significant system costs. Hence, to promote CR implementation, measures such as obliging direct waste incineration to trade CO2 certificates - provided that certificate prices increase sharply in the future - as well as implementing a recycling rate are found to be necessary to gap economic disadvantages. This study not only contributes to extending life cycle approaches for LCSA methodologically, it furthermore provides valuable insights into temporal and spatial interactions in waste management systems to inform science, industry, and politics about the sustainability impacts of CR on the achievement of the UN-SDGs. -
PublicationDegradation Stability of Solar Cells After Laser Enhanced Contact Optimization (LECO)( 2022)
;Krassowski, EveZhao, HongmingIn this work the influence of the LECO treatment on the typical PERC degradation mechanisms was investigated. It was found that the treatment has no significant impact on the Boron-Oxygen related Light Induced Degradation and Light and elevated Temperature Induced Degradation behavior. Furthermore, it is shown that stabilized cells remain stable after the LECO treatment. Also, we did not find any indication of LECO influencing the Potential Induced Degradation susceptibility. Finally, the variation of the process order of the LECO treatment and the B-O Stabilization Process was analysed and showed no restrictions or differences in the outcome of the solar cell quality or stability. Based on these results it is proposed to implement LECO as an approach to decrease the LeTID-sensitivity by combining LECO with modified firing processes. We claim that a combination of reduced peak firing temperatures with the LECO process leads to a decrease in LeTID sensitivity without any drawbacks in the cells' efficiencies. -
PublicationEnhancing the Levelized Cost of Hydrogen with the Usage of the Byproduct Oxygen in a Wastewater Treatment Plant( 2023)
;Hönig, Franziska ;Duque-Gonzalez, Diana ;Ebert, MatthiasBlum, UlrichIn order to harmonize the supply and demand of green energy, new future-proof technologies are needed. Here, hydrogen plays a key role. Within the current framework conditions, the production of green hydrogen is not yet economically viable. The use of the oxygen produced and the possible increase in efficiency associated with it mostly remain unconsidered. The aim is to demonstrate that the economic efficiency of a power-to-gas (PtG) project can be increased by using the byproduct oxygen. In this research project, a water electrolyzer connected to grid is powered to supply hydrogen to a hydrogen refueling station. By utilizing the byproduct oxygen from water electrolysis for a wastewater treatment plant (WWTP), it is shown that the net present value (NPV) of the project can be improved by up to 13% compared to the initial scenario. If a photovoltaic (PV) system is used in addition to grid electricity for higher green hydrogen production, the NPV can be further improved by up to 58%. The levelized cost of hydrogen (LCOH) is calculated for different scenarios with and without oxygen configuration. A sensitivity analysis is then performed to find important parameters. -
PublicationFast Changing Field Effect Passivation States due to Potential Induced Degradation at the Rear Side of Bifacial Silicon Solar Cells( 2022)
;Hevisov, David ;Dittmann, SebastianThe rear side of bifacial silicon solar cells can suffer potential induced degradation (PID) when subject to high voltage stress. The PID of the polarization type (PID-p) has its largest impact on the rear side short circuit current and is attributed to loss of surface passivation. In this study, PID tests at bifacial silicon solar cells reveal fast transient changes of rear side short circuit current within minutes when subject to voltage stress at the rear. The short circuit current measured under rear side illumination first decreases significantly and increases subsequently reaching almost the level of the initial state. This effect can be explained by field-induced band banding near the rear surface. -
PublicationI-V-curve analysis using evolutionary algorithms: Hysteresis compensation in fast sun simulator measurements of HJT cells( 2022)
;Hevisov, DavidState-of-the-art solar cell technologies, such as hetero-junction cells or PERC cells, exhibit a time-dependent deformation of their current-voltage characteristics in fast solar simulator measurements. This hysteresis effect is due to an increased internal capacitance. It manifests itself as a pronounced difference between I–V-curves depending on the measurement direction, i.e. Isc→Voc or Voc→Isc. Thus, it leads to an imprecise determination of the cell performance parameters in particular at the maximum power point. In this study, an algorithm-based correction procedure for these capacitance-induced effects is presented. Using evolutionary optimization algorithms, our correction approach allows the determination of a steady-state curve together with the extraction of all cell parameters featured in a time-dependent equivalent circuit model. It can be implemented without any hardware upgrades and applied to measurement times as low as a few milliseconds. As our basic approach is entirely independent of the underlying model, it is applicable to any solar cell technology by adapting the model under consideration. -
PublicationInvestigation of element enrichment in silicone gels used to encapsulate inverter modules for renewable power generation( 2022)
;Giebel, Elisabeth ;Böttge, BiancaThe focus of this study is to investigate the enrichment of impurities within the silicone gels protecting power electronic modules during application. For this purpose, the power modules of three photovoltaic (PV) string inverters installed at different locations and after an operation time of approximately 8 years were compared with modules tested in a continuous condensation test and the respective reference modules. Impurities found in the silicone gel were correlated to possible sources, such as polymer housing or electronic components. -
PublicationModeling of Manufacturing Induced Residual Stress in 3D-Printed Components( 2022)
;Panchasara, Kevin ;Ramakrishnan, Anantha Narayanan ;Mehle K., K. ;Ludtka, C.The objective of this work is to model the residual stresses that can arise during the production of components using fused deposition modeling (FDM). Thermally induced residual stresses occur during the manufacturing process due to unfavorable thermal conductivity of the polymers used. For this purpose, the G-code of a 3D printer is first imported into a column interpreter which can be rearranged according to given requirements. This is done using a Visual Basic macro. This geometry data is further processed using a CATIA macro to create a geometry in CATIA. For simplification a circular profile is used, which is extruded over polymer lines and stacked on top of one another. In concert, the time-varying assignment of the boundary conditions over which the printing process is simulated is performed. The calculations are made in ANSYS Workbench using ANSYS APDL commands. The element activation-deactivation method is used for the simulation. The thermal simulation is first demonstrated and validated on a sample block and then transferred to the CAD part. The results are imported from Transient Analysis and used as load steps for the Static Structural Analysis, where stresses, strains, and deformations are calculated. The results are then studied to finally print the geometry. -
PublicationPotential failure modes of cement-based encapsulation concepts for reliable power electronics( 2022)
;Böttge, BiancaThe introduction of new encapsulation materials – like cement-based concepts – with enhanced thermal, mechanical and thermomechanical properties is one opportunity to increase the performance and reliability of power electronic devices. Within first studies, an increase of lifetime by a factor 2.3 was observed in power cycling tests for “Econo3” power modules with cement-based encapsulation in comparison to modules encapsulated with standard silicone gel. Finite element analysis has shown variations of the local stress distribution during power-cycling test resulting in potential new or modified failure modes. In order to verify the outcomes of finite element modelling, comprehensive failure analysis was performed. As a result, a failure catalog will be presented including and discussing potential new failure modes. In addition, the impact to well-known failure modes – based on modified material properties of the cement-based encapsulation – is discussed. The analyzed failure modes include crack propagation within the cement-based encapsulant itself, fracture and wear out issues related to chip-or substrate failure as well as bond wire and solder fatigue.