TU Delft Repository

The adoption of Vapour Compression Cycle (VCC) refrigeration technology in aircraft Environmental Control Systems (ECS) presents efficiency advantages over conventional Air Cycle Machine (ACM) architectures. However, the implementation of VCCs in aviation remains a challenge due to excessive system weight, negative environmental impact of refrigerants, and high control complexity. This study focuses on the Inverse organic Rankine cycle Integrated System (IRIS) at TU Delft, which investigates electrically driven VCC systems with novel refrigerant types for aircraft applications. A dynamic model of the IRIS refrigeration loop is developed to assess transient behaviour and evaluate the performance of a high-speed centrifugal compressor to be integrated into the system. The model employs a modular, physics-based approach using the Modelica/Dymola environment, incorporating the Moving Boundary method for heat exchangers and steady-state performance maps for the compressor. Model verification is performed through steady-state and transient analyses. Subsequently, a linear decentralized control strategy is designed to regulate the compressor inlet and outlet conditions, ensuring stable operation across varying test conditions. Simulation results demonstrate that the controller successfully regulates the refrigeration loop of the IRIS to reach the desired setpoints for full compressor testing, while keeping inputs within operational limits. Additionally, it is shown that key system dynamics are correctly captured by the model, providing valuable insights into the operational feasibility of centrifugal VCCs in aerospace ECS applications.

In summary, the contributions within this thesis advance Alzheimer's research by introducing new computational tools and methods to better understand the genetics of the disease and cellular mechanisms. Additionally, showing that single-cell gene expression can be effectively analyzed in a binary format (expressed or not) simplifies genomic data analysis, making it more accessible, efficient, and applicable to a range of diseases and conditions.

This thesis presents the design process of a novel noise barrier design made from horizontally arranged, decommissioned wind turbine blade material.

To address climate change challenges worldwide, wind power is increasingly being adopted. The wind turbine blades (WTBs) used for them are decommissioned after 20-25 years, at which point a problem emerges: the complex material composition makes that current end-of-life options result in the loss of material value without regaining significant economic value. The aim is therefore to structurally reuse WTB material in applications that preserve material integrity and prolong its lifetime. Scalable and long-lasting noise barriers are consequently identified as a fitting opportunity. This thesis focuses on horizontal arrangements of WTB material for use in a noise barrier as this is underexplored and will more closely resemble conventional building materials.

However, due to the variable curved shapes of WTBs, seamless assembly in noise barriers becomes challenging. Especially since gaps compromise the noise attenuation of a noise barrier. The proposed design is a solution to that challenge. It configures WTB panels in modular cassette-panel-cassette sections that allow for tackling alignment issues and can be easily (dis)assembled on frame structures. It attenuates noise by reflecting sound waves into the sky off of tilted, continuous front panels. A second column of panels further reduces sound transmission behind the barrier. Continuity and aesthetic harmony of the barrier in its surroundings is aimed for by use of climbing plants and a green colour palette.

The design follows from a process based on research. Led by a vision on durability, modularity and feasibility, ideas are developed into two concepts that are evaluated with input from experts. Subsequently, one integrated concept is further developed through (CAD) modelling, prototyping, testing, simulating, and a survey.

Three research questions are answered throughout this process. To ensure seamless fitting, a parametric model is developed to inform segmentation strategies. It filters out excessively curving parts to retrieve suitable panels. Alternating the orientation of cladded panels and avoiding seams in the road-side surface of the assembly further tackle alignment issues. Analysis of existing noise barriers reveals that mounting and assembly are facilitated by use of modular cassette-based systems. Cassettes can accommodate the WTB panels that contain variable curvature. A prototype is developed to test fastening options, resulting in an adjustable and reversible clamp design that allows for acoustic sealing. The resulting cassette-panel-cassette modules can be pre-fabricated off-location to reduce time spent on-location. Maintaining opportunities for next material lifecycles is found to largely depend on resizing activities. Large panels are prioritized as they can be more broadly reused than smaller ones. Additionally, protecting exposed core materials of sandwich structures (balsa wood and foam) against weathering is important. An explorative test with epoxy coatings provides starting insights to this end.

Overall, the valuable insights in this thesis culminate in a functional, feasible and desirable noise barrier made of WTB material, and highlights areas for further industry research.

This thesis presents the optimization of chord-bracing connections (tubular joints) in lattice boom structures using Wire Arc Additive Manufacturing (WAAM). The research aims to enhance the static and fatigue performance of critical joints, with a focus on the 1600mt LEC crane boom, which is used for offshore wind turbine installation. Through the integration of topology optimization and WAAM, the study seeks to improve structural efficiency by optimizing weld geometry and material distribution.
Finite Element Analysis (FEA) was employed to identify high-stress regions within the tubular joints, followed by topology optimization to refine their design. The study also investigates the impact of WAAM on material efficiency, fabrication flexibility, and the overall mechanical properties of the joints. The results demonstrate that the optimized tubular joints exhibit significant improvements in fatigue life and static strength compared to traditional designs, providing a more robust and cost-effective solution for lattice boom applications.
The findings of this research contribute to advancing the use of additive manufacturing in structural engineering, particularly in enhancing the performance and sustainability of offshore crane systems. The proposed optimization framework and design methodologies offer valuable insights for future applications of WAAM in heavy-duty structural components.

This thesis investigates the practical connection between health-promoting evidence and the spatial design of blue spaces. This endeavour aims to develop instrumental resources that facilitate the integration of the health benefits of natural environments into actionable strategies, thereby augmenting the development of design research and enhancing understanding of the nature-health nexus. The research methodically examines three interrelated aspects: understanding the academic contexts and methodological preparation from the design perspective, development of qualitative and quantitative design knowledge for fulfilling health benefits of blue spaces, and applications and reflections on proposed knowledge through design workshops and interviews. Initially, the thesis outlines the relationship between blue space and health from a design perspective, identifying a significant, unexplored gap. It then proposes a methodological framework to translate health-promoting evidence of blue spaces into design knowledge for practices. Subsequently, this thesis employs interdisciplinary techniques, integrating both qualitative and quantitative approaches, to generate varied types of design knowledge, including distilling worldwide precedent cases, summarising diverse geospatial and visualisation tools, and translating site-based evidence using spatiotemporal crowdsourcing data. The effectiveness and usability of the proposed knowledge are evaluated through design workshops, complemented by expert interviews across various fields, providing insights that reflect on the research outcomes and suggest future directions. Overall, by focusing on the interactive relationship between research and design, the principal contribution of this research lies in its attempt to translate theoretical evidence from public health into practical design interventions, exploring the potential of interdisciplinary tools and methods in facilitating this process.