Fachbereich - Maschinenbau und Verfahrenstechnik
Refine
Year of publication
Document Type
- Article (352)
- Conference Proceeding (225)
- Announcement (115)
- Part of a Book (55)
- Workingpaper / Report (31)
- Article trade magazine (23)
- Doctoral Thesis (10)
- Book (7)
- Collection (6)
- Preprint (5)
Language
- English (512)
- German (335)
- Multiple languages (1)
Keywords
- Luftreinhaltung (130)
- Amtliche Mitteilungen (110)
- Prüfungsrecht (77)
- Prüfungsordnung (66)
- Numerische Strömungssimulation (43)
- Messtechnik (42)
- Bachelor (41)
- Master (41)
- MV (31)
- Maschinenbau (30)
Department/institution
- Fachbereich - Maschinenbau und Verfahrenstechnik (848)
- Hochschulverwaltung (115)
- Fachbereich - Architektur (6)
- Fachbereich - Wirtschaftswissenschaften (6)
- Fachbereich - Design (4)
- Fachbereich - Elektro- & Informationstechnik (4)
- Fachbereich - Sozial- & Kulturwissenschaften (4)
- Fachbereich - Medien (3)
- Hochschulbibliothek (2)
- Hochschule Düsseldorf (1)
Moral Capital und Innovation
(2026)
Die Energiewende erfordert eine tiefgreifende Umstellung des Wärmesektors, der in Deutschland etwa die Hälfte des Endenergieverbrauchs verursacht und noch immer stark auf fossile Energieträger angewiesen ist. Hybride Wärmeerzeugungssysteme, die konventionelle und erneuerbare Quellen wie Blockheizkraftwerke, Wärmepumpen und Solarthermie integrieren, gelten als vielversprechender Lösungsansatz. Ihre steigende Komplexität stellt jedoch hohe Anforderungen an das Energiemanagement. Diese Dissertation untersucht, inwieweit eine datenbasierte modellprädiktive Regelung (engl. Model Predictive Control, MPC) zur Optimierung des Betriebs solcher Systeme in einem Niedertemperatur-Nahwärmenetz beitragen kann.
Kern der Arbeit ist die Entwicklung von Approximationsmodellen und deren Einbindung in eine MPC, die automatisiert und prädiktiv die Fahrweise der Erzeuger steuert. Die Umsetzung erfolgt zunächst in einem Simulationsumfeld, anschließend im Reallabor. Dabei wird neben einer monokriteriellen Optimierung hinsichtlich Betriebskosten und Emissionen sowie einer multikriteriellen Optimierung beider Zielgrößen auch ein kombiniertes Offline-/Online-Optimierungskonzept betrachtet, bei dem am Vortag ein optimaler Fahrplan erstellt und am Erfüllungstag in Echtzeit angepasst wird.
Die Ergebnisse zeigen, dass die MPC im Simulationsumfeld eine flexible, preis- und emissions-sensitive Betriebsweise ermöglicht. Im Reallabor konnten diese Erfolge jedoch nur zum Teil repliziert werden, insbesondere aufgrund von Prognoseunsicherheiten sowie technischen Restriktionen und Unzulänglichkeiten beim Betrieb einzelner Systemkomponenten. Als Erkenntnisse folgen daraus die Notwendigkeit eines robusten MPC-Designs, einer für sie aktuellen und relevanten Datenbasis sowie einer kontinuierlichen Modellpflege.
Die entwickelten Methoden sind grundsätzlich auf andere hybride Wärmenetze übertragbar, erfordern jedoch eine anlagenspezifische Anpassung. Die Arbeit liefert damit praxisnahe Erkenntnisse für die Planung und Regelung nachhaltiger Wärmesysteme im Kontext der Transformation des Energiesystems.
Naturally ventilated educational buildings frequently struggle to maintain adequate indoor air quality (IAQ) under variable occupancy and user-driven ventilation behavior. This exploratory case study evaluates IAQ using the CO2-concentration as an IAQ-indicator in 14 naturally ventilated rooms of six different educational facilities during the heating season in Germany, examining the effects of room design, occupancy, and ventilation practices. After evaluation against current German design recommendations, all investigated rooms reveal the conditional necessity of a mechanical ventilation system. However, all investigated rooms are exclusively ventilated naturally. Continuous monitoring of occupied rooms revealed mean indoor CO2-concentrations – grouped into categories (I to IV) according to EN 16798–1 – ranging between 233 ppm and 383 ppm (category I), 654 ppm and 691 ppm (category II), 910 ppm and 1097 ppm (category III), and 1409 ppm and 2553 ppm (category IV) above the outdoor CO2-concentration. The corresponding frequency of the prevailing CO2-concentrations during the room occupancy periods in the categories I to IV range between 6% and 63% (category I), 9% and 38% (category II), 10% and 42% (category III), and 0% and 59% (category IV). Occupant-specific ventilation rates – determined based on the CO2-decay method – varied substantially (4–188 m³ h⁻¹ occupant⁻¹). Seven of the 14 investigated rooms failed to meet the German Federal Environment Agency’s minimum ventilation rate of 25–30 m³ h⁻¹ occupant⁻¹ under typical operating conditions. Corresponding area-specific ventilation energy losses during the German heating period were estimated to range between 1 kWh m−2 a−1 to 40 kWh m−2 a−1. To translate exposure patterns into management guidance, a CO₂-based 4 × 4 risk matrix was developed, integrating exceedance severity (based on EN 16798–1 categories) and occurrence frequency. While most rooms showed only moderate CO₂ elevations for limited occupied periods, two of the 14 investigated rooms (14%) were classified as high IAQ risk in the proposed matrix, indicating severe and frequent exceedances of hygienically acceptable conditions. The proposed risk-matrix framework provides a reproducible decision-support tool for prioritizing ventilation improvements in naturally ventilated educational sector buildings. By linking exposure severity, likelihood, and energy implications, the approach supports IAQ management under operational and structural constraints.
This thesis addresses two primary goals. The first goal focuses on implementing multi-level hp refinements in conjunction with the Finite Cell Method (FCM) within a finite element framework and assessing their accuracy and convergence behavior. The multi-level hp Finite Element Method (FEM) is demonstrated to yield smaller errors per degree of freedom compared to standard global refinement schemes, particularly in scenarios with non-smooth solutions. Overlay refinements also enable exponential rates of convergence, surpassing the capabilities of the standard p-version for capturing small-scale solution characteristics. Additionally, the integration of the Kelly estimator with multi-level hp FEM facilitates automated mesh refinements based on a posteriori error estimates. In the context of the FCM, which uses non-boundary-fitted structured meshes, accurate integration of cells intersecting the domain boundary preserves convergence properties for high-order approaches. Preconditioners specific to the FCM mitigate ill-conditioned element matrices, enhancing the convergence behavior of linear solvers. Finally, the combination of the FCM with multi-level hp FEM successfully simulates deformation and stress distribution within an aluminum foam pore, demonstrating its potential for accurate structural analysis.
The second goal focuses on assessing a small-strain plasticity model in conjunction with overlay refinements and the finite cell method. While time constraints limited the scope of this objective, the J2 flow theory for simulating plastic deformation in ductile materials was implemented. This model was applied alongside the finite cell method to solve a benchmark problem, demonstrating good agreement with reference solutions from the literature. Automated overlay refinements further improved solution accuracy in critical regions of the domain.
Standard 16000-8 of the International Organization for Standardization (ISO 16000-8) specifies the assessment of ventilation performance using age-of-air concepts and tracer gas techniques. Since its publication in 2007, ventilation systems and assessment practices have evolved considerably, driven by increased use of mixed-mode and decentralized ventilation and advances in modeling and measurement technologies. This review examines how ISO 16000-8 can be modernized to harmonize with adjacent ventilation and indoor air quality standards while remaining applicable to contemporary systems and emerging approaches. A structured literature search of Web of Science and Google Scholar identified 76 studies (2007–2026) that engage with ISO 16000-8, age-of-air metrics, or tracer gas-based assessment. The literature was synthesized qualitatively using the framework of Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA), classifying studies into performance assessment, measurement–simulation convergence, and standardization discourse. The synthesis shows that while the conceptual foundations of ISO 16000-8 remain valid, assumptions of homogeneous mixing and steady-state conditions are often violated in real buildings, leading to inconsistent application of age-of-air indicators. Field and laboratory studies under point-source conditions demonstrate reduced ventilation effectiveness of 0.73–0.82 in classrooms and 0.5–1.4 in various indoor environments, instead of ≈1 for perfect mixing. Spatial heterogeneity is also observed in mixed-mode systems, with an efficiency around 0.5. In decentralized and façade-integrated systems, air exchange effectiveness deviates from theoretical expectations, indicating inhomogeneous air renewal and short-circuiting. Field measurements show configuration-dependent discrepancies in air exchange rates (e.g., carbon dioxide vs. perfluorocarbon tracer methods under varying door positions), while wind induces time-varying infiltration. Collectively, the literature demonstrates systematic violations of well-mixed and steady-state assumptions underpinning ISO 16000-8. Fragmentation between ventilation performance standards and indoor air quality regulation limits practical uptake. Emerging experimental, numerical, and data-driven methods complement ISO 16000-8, provided applicability domains and uncertainties are addressed. The review concludes that ISO 16000-8 should be modernized toward a harmonized, performance-based framework integrating diverse ventilation systems and assessment technologies.