Eldorado - Repositorium der TU Dortmund
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Aktuellste Veröffentlichungen
Item type:Item, Power-dependent efficiency model of EV chargers for distribution grid simulations(2025) Masuch, Marius; Esser, Marcel; Spina, AlfioThe growing adoption of Electric Vehicles (EVs) and their integration into electrical distribution grids present various challenges. Among others, the efficiency of bidirectional chargers is critical for accurate energy demand forecasting and charging schedule optimisation. This study adapts a mathematical efficiency model, originally developed for photovoltaic inverters, for application to bidirectional EV chargers and incorporates the charging operation into a distribution grid simulation. To account for the power-dependent efficiency of chargers under diverse charging conditions, an approximation based on a step-function is employed. Simulation results indicate that incorporating variable charger efficiency leads to a moderate increase in total EV energy demand (9.4 %) and a minor increase in transformer loading during charging events (0.4 %), while the impact on line loading remains negligible in the considered scenario. The developed variable efficiency model provides a foundation for future research in larger networks with higher EV penetration levels also incorporating functionalities such as Vehicle-to-Grid.Item type:Item, Highly efficient lithium extraction from magnesium-rich brines with ionic liquid-based collaborative extractants(2023-12-25) Yu, Gangqiang; Zhang, Xinhe; Hubach, Tobias; Chen, Biaohua; Held, ChristophSelective extraction of Li+ from high Mg2+/Li+ ratio brines with ionic liquid (IL) based collaborative extractants was investigated by experiments, thermodynamic analyses, and quantum chemical (QC) calculations. Effects of different IL cationic structures and organophosphorus ligands on extraction performances were studied. The results demonstrated that the system 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide + trioctyl phosphate ([HOEMIM][Tf2N] + TOP) was considered as the best extractant, with the very high extraction efficiency of Li+ (83.16 %) and separation selectivity of Li+/Mg2+ (742.11), which is higher than values reported in literature. The thermodynamic model ePC-SAFT was first extended to quantitatively predict the phase equilibria of the so-called “organic–inorganic complex strong electrolyte system” presented in this work. The molecular-level extraction mechanism was explored by QC calculation, indicating that the strong multi-site intermolecular interactions between Li+ and [HOEMIM][Tf2N] + TOP break the Li+ hydration. This work provides guidance to rationally design novel IL-based extractants for efficient extraction of Li+.Item type:Item, H2 production under stress: [FeFe]‑hydrogenases reveal strong stability in high pressure environments(2024-03-11) Edenharter, Kristina; Jaworek, Michel W.; Engelbrecht, Vera; Winter, Roland; Happe, ThomasHydrogenases are a diverse group of metalloenzymes that catalyze the conversion of H2 into protons and electrons and the reverse reaction. A subgroup is formed by the [FeFe]‑hydrogenases, which are the most efficient enzymes of microbes for catalytic H2 conversion. We have determined the stability and activity of two [FeFe]‑hydrogenases under high temperature and pressure conditions employing FTIR spectroscopy and the high-pressure stopped-flow methodology in combination with fast UV/Vis detection. Our data show high temperature stability and an increase in activity up to the unfolding temperatures of the enzymes. Remarkably, both enzymes reveal a very high pressure stability of their structure, even up to pressures of several kbars. Their high pressure-stability enables high enzymatic activity up to 2 kbar, which largely exceeds the pressure limit encountered by organisms in the deep sea and sub-seafloor on Earth.Item type:Item, How does corporate culture affect IPO price formation?(2024-03-25) Cumming, Douglas; Köchling, Gerrit; Neukirchen, Daniel; Posch, Peter N.We examine the relationship between corporate culture and initial public offering (IPO) price formation. Using a sample of 935 US IPOs and data on corporate culture from Li et al. (2021b), we find that IPOs of strong culture firms are associated with more positive price revisions and higher initial returns, i.e., more underpricing. These findings hold using an alternative measure of corporate culture, matched samples, and a large set of control variables. Consistent with key theories, the effects appear to be driven by underwriters deliberately compensating investors for revealing information about their perceptions of the firm's culture during bookbuilding.Item type:Item, Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 7/2026(Technische Universität Dortmund, 2026-03-17)