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Vibro-assisted fluidization of cohesive micro-silica has been studied by means of X-ray imaging, pressure drop measurements, and off-line determination of the agglomerate size. Pressure drop and bed height development could be explained by observable phenomena taking place in the bed; slugging, channeling, fluidization or densification. It was observed that channeling is the main cause of poor fluidization of the micro-silica, resulting in poor gas-solid contact and little internal mixing. Improvement in fluidization upon starting the mechanical vibration was achieved by disrupting the channels. Agglomerate sizes were found to not significantly change during experiments., ChemE/Product and Process Engineering, ChemE/O&O groep

In this study, the impact of different vibrational modes on the fluidization characteristics of cohesive micro- and nano-silica powder was examined. Fractional pressure drop, bed expansion measurements, and X-ray imaging were utilized to characterize the fluidization quality. The densities of the emulsion phase at the top and bottom of the column were quantified and compared, providing insights into the solid distribution within the fluidized bed. In the absence of vibration, neither powder could be fluidized within the considered range of superficial gas velocities. Vertical vibration was found to initiate fluidization for both powders. In contrast, elliptical vibration failed to overcome the channelling behavior when fluidizing the micro-powder. For nano-powder, combined channelling and powder compaction occurred when the bed was subjected to elliptical vibration. For the micro-powder, it was observed that bed homogeneity was independent of vertical vibration intensity but improved with increasing superficial gas velocity. For nano-powder, intensifying vertical vibration led to segregation, likely due to agglomerate densification. Furthermore, fractional pressure drop measurements proved to be a strong tool in assessing fluidization quality, providing insights that could not be attained by conventional indicators., ChemE/Product and Process Engineering, Sanitary Engineering

Stirring has been recognized in the literature as a promising technique for facilitating fluidization of cohesive powders, via inputting additional energy to counteract interparticle forces. However, the influence of operating conditions and stirrer configurations on flow behavior remains largely unknown, which impedes the practical implementation of stirred fluidization. Utilizing X-ray imaging, this research demonstrates that stirring enhances fluidization in cohesive micron-silica powder (Sauter mean diameter [Formula presented]) by collapsing the powder packing structure, and transitioning channeling beds into bubbling states. Comb-like configurations featuring fewer stirrers and blades, placed in the bottom region, have shown to be highly effective. Excessive stirring can lead to air pockets and a compacted phase of particles on the column walls, undermining the interaction between particles and stirrers. Additionally, the experiments show that maximizing the sweeping coverage, employing complex asymmetrical configurations, and avoiding tortuous gas pathways are preferable., ChemE/Product and Process Engineering, BT/Industriele Microbiologie, ChemE/O&O groep

Consumer goods supply chains are intensifying their efforts to develop and offer green products, in order to seize new business opportunities and improve profitability. A specific type of green products concerns marginal and development cost-intensive green products (MDIGPs), like electric vehicles. As greening these products affects both marginal and development costs, their design presents special challenges, especially within the context of uncertain demand. This paper formulates the joint product pricing-ordering-greening decision problem in the supply chains of MDIGPs and examines the impact of demand uncertainty. A sequential game-theoretic framework is developed, providing analytical expressions of the optimal solutions for the stochastic model. A bargaining game on the wholesale price between supply chain members is proposed to coordinate decisions. We compare the optimal decisions numerically in the stochastic and deterministic cases and find that, although demand uncertainty creates inefficiency in the green supply chain, it might positively impact product greenness and prices. Given the impact of the unit-variable greening costs of MDIGPs, we are able to identify cases where–contrary to common belief–demand uncertainty does not always lead firms to reduce greenness or increase prices., Transport and Logistics, Delft Center for Systems and Control, Transport and Planning

Additive manufacturing offers a significant potential for producing metallic parts with distinctly localised microstructures and mechanical properties, commonly known as functional grading. While functional grading is generally accomplished through compositional variations or in-situ thermo-mechanical treatments, variation of process parameters during additive manufacturing can offer a promising alternative approach. Focusing on the electric arc-based additive manufacturing process, this work focuses on the functional grading of high-strength steel (S690 grade) by adjusting the travel speed and inter-pass temperature. Through a combination of thermal simulations and experimental measurements on single bead-on-plate depositions, it is shown that the microstructure and the mechanical properties of parts can be controlled through the rational adjustment of process parameters. A rectangular block was fabricated to demonstrate functional grading using a constant wire feed rate and varying travel speed. The rectangular block consisted of a low heat input (LHI) region deposited between high heat input (HHI) zones. A graded microstructure was obtained with the HHI zones composed of a mixture of polygonal ferrite, acicular ferrite, and bainite, while the LHI region was primarily composed of martensite. The hardness and profilometry-based indentation plastometry measurements indicated that the LHI region exhibited higher hardness (32%) and strength (50%), but lower uniform elongation (80%), compared to the HHI zones. The present study demonstrates the potential to achieve functional grading by adjusting process parameters in electric arc-based additive manufacturing, providing opportunities for tailor-made properties in parts., Team Marcel Hermans

Wire and Arc Additive Manufacturing (WAAM) emerged as a manufacturing process for large scale structures with extensive form and design freedom. WAAM can be fully exploited once the relation between the transient thermal history and its relation to microstructure development and resultant mechanical properties is established. This relation can be further used for computational design tools such as Topology Optimization. This paper presents a model to predict the relation between the thermal history and solid-state phase transformations in a widely applicable High Strength Low Alloy steel ER110S-G. The transient thermal history of parts manufactured by WAAM is modelled using finite element analysis. The modelled thermal history is validated with thermocouple measurements. Our results show that a critical cooling cycle is responsible for the solid-state phase transformation in an AM part. The cooling rate of this particular cooling cycle is superimposed onto an experimentally constructed Continuous Cooling Transformation (CCT) diagram to determine the local solid-state phase fractions. The predicted phase fractions in three wall samples with different design and processing conditions of AM parts are used to predict the hardness. The predicted hardness is 10% higher than the measured hardness of AM samples. The effect of tempering is also considered in the model through JMAK equation. The results show that the tempering is caused in regions with high martensite content and it lowers the hardness by 8 − 10%. The micrographs of the AM parts show that the microstructural features are same for the AM parts with similar critical cooling rates., Computational Design and Mechanics, Team Marcel Hermans

The fluidization of cohesive powders has been extensively researched over the years. When looking at literature on the fluidization of cohesive particles, one will often find papers concerned with only micro- or only nano-sized powders. It is, however, unclear whether they should be treated differently at all. In this paper, we look at differences and similarities between cohesive powders across the size range of several nanometres to 10s of micrometres. Classification of fluidization behaviour based on particle size was found to be troublesome since cohesive powders form agglomerates and using the properties of these agglomerates introduces new problems. When looking at inter-particle forces, it is found that van der Waals forces dominate across the entire size range that is considered. Furthermore, when looking into agglomeration and modelling thereof, it was found that there is a fundamental difference between the size ranges in the way they agglomerate. Where the transition between the types of agglomeration is located is, however, unknown. Finally, how models are made and agglomerate sizes are measured is currently insufficient to accurately predict or measure their sizes consistently., ChemE/Product and Process Engineering

Pressure and temperature are the most important state variables for monitoring physicochemical processes to detect deviations that might lead to explosions and to verify levels, flow rate, and solids/gas hold-up. Pressure fluctuations in multi-phase systems identify regime changes and flow anomalies. Pressure signals are the first indicator of a process upset and are tied into distributed control systems (DCS) to sound alarms when they drift to high or low and activate safety interlocks in the case of high, high-high, low, and low-low conditions. To maximize the information, it requires that pressure gauges (transducers) are installed and calibrated precisely. Pressure measuring devices include manometers, aneroid devices like bellows and Bourdon gauges, and electronic instruments—piezoresistive, piezoelectric, and capacitive. The electronic elements have the advantage of higher precision and faster response times to measure fluctuations. The Bourdon gauges are standard equipment for pressure regulators and are mounted on the exterior of vessels and pipes to facilitate visual inspections. Over 2 million articles indexed by the Web of Science Core collection mention pressure, and in 2021, chemical engineering ranks had over 7000 articles—only multidisciplinary material sciences and energy and fuels had more. A bibliometric analysis identified five research clusters: temperature, combustion, and kinetics; separation, membranes, and energy efficiency; carbon dioxide (capture and storage), water, and thermodynamics; methane, adsorption, and transport phenomena (e.g., diffusion and permeability); and modelling, optimization, and computational fluid dynamics (CFD)., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., ChemE/Product and Process Engineering

Recent decades have seen impressive developments in the field of integrated photonics. Chips with complex photonic functionality can presently be designed and fabricated. Photonic packages consist of one or more PICs, as well as other (micro-optical) components, and a fibre (array) to establish the external optical interface. A core challenge is the assembly and packaging of these complex devices, involving sub-μm alignment of components. To overcome the limitations in multi-chip photonic packaging, a concept is proposed which uses on-chip actuators for the fine-alignment of flexible waveguide structures., Micro and Nano Engineering

Photonic packaging, which includes high-precision assembly of photonic sub-systems, is currently a bottleneck in the development of commercially-available integrated photonic products. In the pursuit of a fully-automated, high-precision, and cost-effective photonic alignment scheme for two multi-channel photonic chips, this paper explores different designs of the on-chip electrothermal actuators for positioning mechanically-flexible waveguide structures. The final alignment goal is ~100nm waveguide to waveguide. The on-chip actuators, particularly for out-of-plane actuation, are built in a 16μm-thick SiO2 photonic-material stack with 5μm-thick poly-Si as an electrothermal element. A major challenge of out-of-plane positioning is a 6μm height difference of the waveguides to be aligned, due to different built-up material stacks, together with a misalignment tolerance of 1 μm-2μm from the pre-assembly (flip-chip) process. Therefore, the bimorph-actuator design needs to compensate this height difference, and provide sufficient motion to align the waveguides. We propose to exploit the post-release deformation of so-called short-loop bimorph actuator designs to meet these joint demands. We explore different design variants based on the heater location and the integration of actuator beams with waveguide beams. The actuator design (with 30μm poly-Si and 900μm SiO2 in length) has ~8μm out-of-plane deflection and is able to generate ~4μm motion, which meets the design goal., Micro and Nano Engineering

This paper proposes and tests a design of electro-thermal bimorph actuators for alignment of flexible photonic waveguides fabricated in 16 μm thick SiO2. The actuators are for use in a novel alignment concept for multi-port photonic integrated circuits (PICs), in which the fine alignment is taken care of by positioning of suspended, mechanically flexible waveguide beams on one or more of the PICs. The design parameters of the bimorph actuator allow to tune both the initial relative position of the waveguide end-facets, and the motion range of the actuators. Bimorph actuators have been fabricated and characterized. The maximum out-of-plane deflection of the bimorph actuator (with 720 μm-long poly-Si) can reach 18:5 μm with 126:42mW, sufficient for the proposed application., Micro and Nano Engineering

Fully automated, high precision, cost-effective assembly technology for photonic packages remains one of the main challenges in photonic component manufacturing. Next to the cost aspect the most demanding assembly task for multiport photonic integrated circuits (PICs) is the high-precision (±0.1 μm) alignment and fixing required for optical I/O in InP PICs, even with waveguide spot size conversion. In a European research initiative - PHASTFlex - we develop and investigate an innovative, novel assembly concept, in which the waveguides in a matching TriPleX interposer PIC are released during fabrication to make them movable. After assembly of both chips by flip-chip bonding on a common carrier, TriPleX based actuators and clamping functions position and fix the flexible waveguides with the required accuracy., Micro and Nano Engineering

Materials of steam water cycles can suffer from corrosion induced by halide anions in feedwater. Organic halogen compounds in feedwater can be degraded and release halide anions under high temperature and pressure. Therefore it is necessary to be able to measure the organic halogen concentration. Existing measurements including Adsorbable Organic Halogens and Gas Chromatography are either not convenient, affordable, accurate or reproducible enough at these very low concentrations, meaning a new method should be developed. In this research the option of destroying the organic compounds to release the halide anions and measure them with ion chromatography was studied. The question is, which is the best way to destroy the organic compounds and release the halides anions. Six organic halogen model compounds were tested: aliphatic and aromatic fluorine, chlorine and bromine containing compounds. Two main methods were studied: UV/vacuumUV (VUV) photolysis and wet chemical oxidation with K2S2O8. There are three phases in the research: 1. Study different UV lamps and oxidants on the target compounds and find the optimal combinations. 2. Try different dosages of K2S2O8 and find an optimum. 3. Test halide release of target compounds in power plant conditions. In the experiments, three kinds of lamps were applied: VUV, low pressure (LP) lamp and medium pressure (MP) lamp. H2O2 and TiO2 were used as a catalyst. Last but not least, wet chemical oxidation was tested, with varying dosages of K2S2O8. The experiments were executed with both single compounds and mixed compounds. The results show that the organic fluorine is the hardest to degrade while organic bromine is the easiest. Aromatic compounds are easier to degrade than aliphatic compounds. This happens not only in AOP process, but also in power plant conditions. The recovery of bromide and chloride in most methods could reach 95% while aliphatic fluorine could only reach at most 70%. It can be concluded that MP/H2O2 is the, Sanitary Engineering, Water Management, Civil Engineering and Geosciences

Materials of steam water cycles can suffer from corrosion induced by halide anions in feedwater. Organic halogen compounds in feedwater can be degraded and release halide anions under high temperature and pressure. Therefore it is necessary to be able to measure the organic halogen concentration. Existing measurements including Adsorbable Organic Halogens and Gas Chromatography are either not convenient, affordable, accurate or reproducible enough at these very low concentrations, meaning a new method should be developed. In this research the option of destroying the organic compounds to release the halide anions and measure them with ion chromatography was studied. The question is, which is the best way to destroy the organic compounds and release the halides anions. Six organic halogen model compounds were tested: aliphatic and aromatic fluorine, chlorine and bromine containing compounds. Two main methods were studied: UV/vacuumUV (VUV) photolysis and wet chemical oxidation with K2S2O8. There are three phases in the research: 1. Study different UV lamps and oxidants on the target compounds and find the optimal combinations. 2. Try different dosages of K2S2O8 and find an optimum. 3. Test halide release of target compounds in power plant conditions. In the experiments, three kinds of lamps were applied: VUV, low pressure (LP) lamp and medium pressure (MP) lamp. H2O2 and TiO2 were used as a catalyst. Last but not least, wet chemical oxidation was tested, with varying dosages of K2S2O8. The experiments were executed with both single compounds and mixed compounds. The results show that the organic fluorine is the hardest to degrade while organic bromine is the easiest. Aromatic compounds are easier to degrade than aliphatic compounds. This happens not only in AOP process, but also in power plant conditions. The recovery of bromide and chloride in most methods could reach 95% while aliphatic fluorine could only reach at most 70%. It can be concluded that MP/H2O2 is the, Sanitary Engineering, Water Management, Civil Engineering and Geosciences