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Evaluation of VSC Impact on Power System Using Adequate P-Q Capability Curve
- Michal Brodzicki
- Jacek Klucznik
- Stanisław Czapp
2023 Pełny tekst Electronics
Renewable energy sources, which are becoming increasingly popular, often use a voltage source converter (VSC) for connection to the power system. Assessing the effects of connecting such a source to the power system is essential to ensure the proper operation of the power system and the connected source. For this purpose, it is necessary to know the range of active and reactive power generation by the converter. The authors indicate that the interaction between the power system and the converter affects its range of available active and reactive power. Therefore, a strictly defined range of the converter’s generating capability should not be assumed as invariant, but its capability for a given operating condition of the power system should be determined iteratively. In order to confirm this thesis, the authors analyzed the operation of the VSC-based energy source in an example power system using the PowerFactory software. Extending the calculation procedure to include iterative determination of the converter’s available power range showed a significant influence of the system’s operating state on the converter’s generating capabilities. The results obtained in this work extend the knowledge, and thanks to them, the operation of VSC systems can be modelled more accurately.
Event-Triggered Communication in Cooperative, Adaptive Model Predictive Control of a Nuclear Power Plant’s Turbo–Generator Set
- Pawel Sokolski
- Tomasz Rutkowski
- Bartosz Ceran
- Daria Złotecka
- Dariusz Horla
2023 Pełny tekst ENERGIES
This paper discusses the issue of optimizing the communication between the components of a cooperating control system formed by a pair of MPC controllers of a nuclear power plant turbine set using online recursive least squares identification. It is proposed to use event-triggered communication, i.e., sending information only at selected time instants, as opposed to the standard approach where communication is triggered by time (time-triggered approach). The aim of this paper is to propose a change in the method of information exchange in the case of asynchronous communication between control system components and to prove its suitability for the selected application. Resignation from continuous communication in favor of sending information only at selected moments allows the load on the communication network to be reduced by approximately 90% while maintaining the quality of control.
Evolution of Physical Properties of RE 3 Ni 5 Al 19 Family (RE = Y, Nd, Sm, Gd, Tb, Dy, Ho, and Er)
- Zuzanna Ryżyńska
- Madalynn Marshall
- Weiwei Xie
- Tomasz Klimczuk
- Michał Winiarski
2023 Pełny tekst CRYSTAL RESEARCH AND TECHNOLOGY
Single crystals of RE3Ni5Al19 series (RE = Y, Nd, Sm, Gd, Tb, Dy, Ho, and Er) are grown using the Al self-flux method. The crystal structure is examined by both single crystal and powder X-ray diffraction. Physical properties are studied for the first time for RE3Ni5Al19 (RE = Y, Nd, Gd, Tb, Dy, Ho, and Er) by means of magnetic susceptibility, electrical resistivity, and heat capacity measurements. Complex magnetic behaviors, with up to three transitions present for RE = Sm, Gd, Tb, and Dy, are revealed. Y3Ni5Al19 is found to be a nonmagnetic nonsuperconducting metal (above T = 1.8 K) with weak electron–phonon coupling strength.
Evolution towards simplicity in bacterial small heat shock protein system
- Piotr Karaś
- Klaudia Kochanowicz
- Marcin Pitek
- Przemysław Domański
- Igor Obuchowski
- Bartłomiej Tomiczek
- Krzysztof Liberek
2023 Pełny tekst eLife
Evolution can tinker with multi-protein machines and replace them with simpler single-protein systems performing equivalent functions in an equally efficient manner. It is unclear how, on a molecular level, such simplification can arise. With ancestral reconstruction and biochemical analysis, we have traced the evolution of bacterial small heat shock proteins (sHsp), which help to refold proteins from aggregates using either two proteins with different functions (IbpA and IbpB) or a secondarily single sHsp that performs both functions in an equally efficient way. Secondarily single sHsp evolved from IbpA, an ancestor specialized in strong substrate binding. Evolution of an intermolecular binding site drove the alteration of substrate binding properties, as well as the formation of higher-order oligomers. Upon two mutations in the α-crystallin domain, secondarily single sHsp interacts with aggregated substrates less tightly. Paradoxically, less efficient binding positively influences the ability of sHsp to stimulate substrate refolding, since the dissociation of sHps from aggregates is required to initiate Hsp70-Hsp100-dependent substrate refolding. After the loss of a partner, IbpA took over its role in facilitating the sHsp dissociation from an aggregate by weakening the interaction with the substrate, which became beneficial for the refolding process. We show that the same two amino acids introduced in modern-day systems define whether the IbpA acts as a single sHsp or obligatorily cooperates with an IbpB partner. Our discoveries illuminate how one sequence has evolved to encode functions previously performed by two distinct proteins.
Examining the Impact of Distance Between VSL Road Signs on Vehicle Speed Variance
- Andrzej Sroczyński
- Andrzej Czyżewski
2023 Pełny tekst IEEE Access
Variable speed limit (VSL) is an intelligent transportation system (ITS) solution for traffic management. The speed limits can be changed dynamically to adapt to traffic conditions such as visibility and traffic volume, curvature, and grip coefficient of the road surface. The VSL traffic sign location problem and attempts to solve it using computer simulation are presented in this paper. Experiments on a selected road segment, carried out using the traffic simulator, have shown that the proposed method allows the driver’s habits to be taken into account so that the location of road signs can be optimized. The observable effect was a reduction in vehicle speeds and speed variance on critical road segments, translating directly into increased safety and harmonized traffic.
Exergetic Analysis of the nCO2PP Cycle with Particular Reference to the Exergy Destruction of Sewage Sludge Due to Gasification
- Kamil Stasiak
- Ivar Ståle Ertesvåg
- Paweł Ziółkowski
- Dariusz Mikielewicz
2023 Pełny tekst
An exergy analysis is carried out on the negative CO2 emission gas power plant (nCO2PP), which integrates the process sections of fuel preparation, power generation and carbon capture. Processes of exergy destruction are studied with particular focus on the process in the gasification unit of the fuel preparation section, where a large amount of exergy is destroyed in various chemical reactions from sewage sludge to producer gas conversion. The largest exergy losses are observed in the wet combustion chamber and in the fuel line with the gasification process and water condensation in the gas scrubber, amounting to 126 kW, 43-45 kW and 56 kW respectively, which corresponds to efficiencies of 62%, 89% and 84% of these units, while the exergy efficiency of the power plant is 29.5%. The integration of the gasification unit with the gas scrubber is investigated, and a heat exchanger combination is considered. Ambient air changes in relative humidity and, due to increasing global greenhouse gas emissions, CO2 concentration are analysed. Insight into the theoretical operation of the power plant through exergy analysis allows energy efficiency to be increased by improving areas of highest exergy destruction. To represent real power plant operation, the analysis is based on an optimized process simulation calculated using the most accurate published equations of state, verified with experimental thermophysical property data from the literature.
Exergy analysis of a negative CO2 emission gas power plant based on water oxy-combustion of syngas from sewage sludge gasification and CCS
- Ivar S. Ertesvåg
- Paweł Madejski
- Paweł Ziółkowski
- Dariusz Mikielewicz
2023 Pełny tekst ENERGY
A power cycle with water-injected oxy-combustion (water cycle) is investigated by exergy analysis. It is fueled with syngas (aka. producer gas) from gasification of sewage sludge. The cycle is equipped with a spray-ejector condenser (SEC). CO2 is separated and compressed for transportation and storage. The net delivered electric power is 31% of the fuel exergy. The task efficiency is 39% when the flue gas bleed to gasification and O2 penalty are subtracted from fuel, and CO2 capture is included in the useful product. The large part of exergy destruction, 80%, pertains to the combustor. Increasing the temperature or the pressure of the combustor outlet (turbine inlet) lead, as expected, to reduced exergy destruction and more power delivery. Reducing pressure of the gas turbine outlet (SEC inlet) also increases power production. Varying pressure and temperature of the SEC outlet affects the distribution of exergy destruction among units of the condenser, however scarcely the overall efficiency. Reducing the ambient temperature, including cooling water temperature, reduces the efficiency of the plant, contrary to the effect of conventional plants. The reason is that the low pressure of SEC relies on the pressure and mass flow of injected water, rather than the temperature.
Exfoliated graphite with spinel oxide as an effective hybrid electrocatalyst for water splitting
- Malgorzata Skorupska
- Kinga Kowalska
- Magdalena Tyc
- Anna Ilnicka
- Mariusz Szkoda
- Jerzy P. Lukaszewicz
2023 Pełny tekst RSC Advances
The aim of the conducted research was to develop hybrid nanostructures formed from MnCo2O4 and exfoliated graphite. Carbon added during the synthesis allowed for obtaining a well-distributed MnCo2O4 particle size with exposed active sites contributing to the increased electric conductivity. The influence of the weight ratios of carbon to a catalyst for hydrogen and oxygen evolution reactions was investigated. The new bifunctional catalysts for water splitting were tested in an alkaline medium with excellent electrochemical performance and very good working stability. The results for hybrid samples show better electrochemical performance compared to the pure MnCo2O4. The highest electrocatalytic activity was for sample MnCo2O4/EG (2/1), where the value of the overpotential was 1.66 V at 10 mA cm−2, and also for this sample a low value of Tafel slope (63 mV dec−1) was denoted.
Experimental and analytical analysis of punching shear in flat slabs supported on column topped with concrete head
- Maciej Grabski
- Andrzej Ambroziak
2023 Pełny tekst CONSTRUCTION AND BUILDING MATERIALS
An experimental laboraatory test of the two series of slab-column elements topped with drop panels of varying sizes is described in this paper. The scope of the paper is to investigate the influence of the drop panel size and stiffness on the behaviour of the connection between the flat slab and the column topped by the concrete head. The impact of the head size and stiffness is analysed analytically and experimentally. The experimental test results show that at a ratio the heads are too flexible to cause punching shear outside the head, confirm significant concentrations of shear forces at the corners of the large support, and show a significant contribution of the linear parts of the control perimeter to the ultimate force transmitted by the slab-column joint. The authors compare the experimental test results with the considered standard calculation methods and indicate the correlations. The paper provides new experimental results and proposals for the application of a reduction factor for permissible shear stresses in the EC2 standard that depends on the dimension of the support. Simultaneously, the experimental results and the comparison with the standard calculations indicate a further need for research on the connection of a slab to a column topped by a drop panel.
Experimental and numerical analysis of the pyrolysis dynamics of a single wood particle: presentation of the radiographic technique
- Paweł Kazimierski
- Katarzyna Januszewicz
- Paulina Hercel
- Dariusz Kardas
2023 Pełny tekst WOOD SCIENCE AND TECHNOLOGY
Pyrolysis is an oxygen-free process for the thermal decomposition of raw materials. The heat conduction and flow of pyrolysis products (i.e., the gas fraction and liquid vapour generated during pyrolysis) influence the process and products. In this work, the influence of the orientation of wooden particle fibres with respect to the direction of the heat source on the dynamics of the process was investigated, where there were two particle sizes oriented along or across the heat source. The novelty of this work lies in the use of a radiographic technique for analysing the influence of wooden fibres' orientation on the degradation process. The research showed that during pyrolysis, the mass loss rate in the particles with fibres oriented across the heat source and along the heat source was different. A similar tendency was characteristic for the drying process. The dynamics of pyrolysis of a single wood particle depends on many factors—particle size, process parameters, arrangement of fibres in wood, etc. The analysis of the dynamics presented in the publications is based on the analysis of the dynamics of mass loss, which is a very large simplification. The publication contains experimental analysis and mathematical calculations of the pyrolysis process for samples of various sizes and samples with different fibre arrangement. The result of the research is the determination of trends regarding the shape of the particle and the arrangement of fibres on the process, which provides knowledge that can be translated into industrial pyrolysis processes.
Experimental and numerical investigation of mercury removal from flue gas by sorbent polymer composite
- Arkadiusz Ryfa
- Robert Żmuda
- Sergiusz Mandrela
- Ryszard Białecki
- Wojciech Adamczyk
- Marcin Nowak
- Łukasz Lelek
- Dominika Bandoła
- Marcin Pichura
- Joanna Płonka
- Magdalena Wdowin
2023 Pełny tekst FUEL
This paper presents an experimental and numerical investigation of the performance of a sorbent polymer composite (SPC) material used for removing mercury from the flue gases in a full-scale industrial installation. The investigated material is an attractive alternative to activated carbon, which is commonly used for this purpose. While the application of the SPC is characterized by high capital expenditures, this technology offers not only very low operating expenditures but also high efficiency. This study investigates the SPC’s mercury reduction capabilities concerning the most important flow parameters such as gas velocity, temperature, humidity, and mercury concentration. Small scale laboratory experiment was used to tune the kinetic data of the mercury adsorption. The resulting sub-model has been built into the CFD simulations validated against measurements at an industrial installation. The results showed that the most important parameters affecting the mercury reduction efficiency were the gas velocity and mercury content in the sorbent material. Numerical simulation proved that the material absorbs mercury within the entire reasonable operating temperature and humidity ranges, regardless of mercury speciation.
Experimental and numerical investigation on shell and coil storage unit with biodegradable PCM for modular thermal battery applications
- Rafał Andrzejczyk
- Tomasz Muszyński
- Kowalczyk Tomasz
- Muhammad Saqib
2023 INTERNATIONAL JOURNAL OF THERMAL SCIENCES
Thermal energy storage (TES) in automotive applications is currently growing in importance. TES can visibly reduce primary energy consumptions, decrease CO2 emission, and improve thermal comfort in electric as well as hybrid vehicles. However, to meet the new ambitious target (15% reduction of CO2 emissions in the new cars until 2025) it is required to use plug-in electric vehicles. For this reason, this paper focuses on the optimization of key coil designing parameters. For the reference geometry, both experimental and CFD results have been presented. The optimization of coil geometrical parameters has been carried out based on numerical modelling. The prototype of TES is proposed as a honeycomb battery of individual modules. The results show that increasing the diameter and pitch of the coil decreases the melting and solidification time by 13.2% and 11.8% respectively for chosen geometry. CFD calculation has also been made for TES with a hexagonal geometry. The best results were obtained for the TES with a cylindrical shell. However, the results for the TES with hexagonal shell were, very similar (the difference was less than 1% of the share of the liquid phase). It is seen that presented coil optimization is also a good fit for TES with hexagonal shell geometry.
Experimental and Numerical Study on Mechanical Characteristics of Aluminum/Glass Fiber Composite Laminates
- M. E. Golmakani
- Tomasz Wiczenbach
- Mohammad Malikan
- E. Z. Karimi
- M. Masoumi
- Victor Eremeev
2023 Pełny tekst MECHANICS OF COMPOSITE MATERIALS
The fiber-metal composites made of aluminum sheets and glass fibers reinforced with a polyester resin as the matrix were studied. The composites were prepared by hand lay-up method. Some aspects of manufacturing affecting the composite behavior were considered. In particular, the influences of the arrangement of layers and their number on the mechanical and physical properties of composites with ten different compositions were investigated. In addition two different densities of glass fibers were considered. The tensile modulus, tensile and impact strengths were determined following ASTM D3039 and ASTM D6110 standards. The results obtained show that the arrangement of the laminate layers influences Young’s modulus and the tensile strength of the composite. The impact test results of the laminated structure reinforced with glass fibers illustrate a significant increase in the impact strength owing to adding the glass fibers compared to the control specimens. The simulations of tests using ABAQUS-based FEA were performed.
Experimental certification of more than one bit of quantum randomness in the two inputs and two outputs scenario
- Alban Jean-Marie Seguinard
- Amélie Piveteau
- Piotr Mironowicz
- Mohamed Bourennane
2023 Pełny tekst NEW JOURNAL OF PHYSICS
One of the striking properties of quantum mechanics is the occurrence of the Bell-type non-locality. They are a fundamental feature of the theory that allows two parties that share an entangled quantum system to observe correlations stronger than possible in classical physics. In addition to their theoretical significance, non-local correlations have practical applications, such as device-independent randomness generation, providing private unpredictable numbers even when they are obtained using devices delivered by an untrusted vendor. Thus, determining the quantity of certifiable randomness that can be produced using a specific set of non-local correlations is of significant interest. In this paper, we present an experimental realization of recent Bell-type operators designed to provide private random numbers that are secure against adversaries with quantum resources. We use semi-definite programming to provide lower bounds on the generated randomness in terms of both min-entropy and von Neumann entropy in a device-independent scenario. We compare experimental setups providing Bell violations close to the Tsirelson's bound with lower rates of events, with setups having slightly worse levels of violation but higher event rates. Our results demonstrate the first experiment that certifies close to two bits of randomness from binary measurements of two parties. Apart from single-round certification, we provide an analysis of finite-key protocol for quantum randomness expansion using the Entropy Accumulation theorem and show its advantages compared to existing solutions.
Experimental comparison of the transition speed of a hydrodynamic journal bearing lubricated with oil and magnetorheological fluid
- G.h.g. van der Meer
- F. Quinci
- Wojciech Litwin
- Michał Wodtke
- R.a.j. van Ostayen
2023 Pełny tekst TRIBOLOGY INTERNATIONAL
A journal bearing test bench is used to find the transition speed between the hydrodynamic and mixed lubrication regimes for a modified magnetorheological (MR) fluid. It is shown that the transition speed of the bearing can be reduced by applying a local magnetic field near minimum film when it is lubricated with the MR fluid, and that this will only marginally increase friction. The lubricating performance of the MR fluid is compared to that of a reference oil, and all experimental results are compared with a Finite Element model based on the Reynolds equation.
Experimental Evaluation of ND: YAG Laser Parameters and Sample Preparation Methods for Texturing Thin AISI 316L Steel Samples
- Ewa Kozłowska
- Sylwia Grabska-Zielińska
2023 Pełny tekst Applied Sciences-Basel
In mechanical and material engineering, the effect of laser texturing depends on many factors besides device specification, primarily the properties of the materials being processed, and, secondly, the preparation of the sample. Laser texturing of thin (<5 mm) samples is mostly performed utilizing short-pulse lasers, but depending on the power of the laser beam, the process can also be performed by using continuous operation lasers. When using a laser beam to modify the surface layer, special attention should be paid to the surface preparation process. Engraving a shiny metal surface can lead to laser beam dispersion and energy loss. Some materials require special preparation and surface darkening in order to be effectively engraved. In the case of engraving, maximizing the efficiency and repeatability of the process is the key to obtaining the desired properties. The aim of the conducted study was to establish satisfying parameters and a sample preparation method for texturing thin AISI 316L samples. Appropriately selected laser parameters added to proper sample preparation. The sanding, etching, and darkening of the surface layer improved the quality of the weld and eliminated problems such as deformation and spark formation that often occur with raw samples during the texturing process.
Experimental Investigation of the Performance of an Innovative Implantable Left Ventricular Assist Device—Proof of Concept
- Krzysztof Tesch
- Ryszard Jasiński
- Leszek Dąbrowski
- Jan Rogowski
2023 Pełny tekst Applied Sciences-Basel
This paper presents the results of experimental performance of an innovative left ventricular assist device working on a specially designed test stand. The introduced invention is mainly applied for supporting the heart in patients with end-stage heart failure accompanied by mitral valve regurgitation and pulmonary hypertension. Moreover, the developed device has the form of a flexible balloon forming an intracardiac inert gas-filled working chamber, which is divided into two smaller balloons (valve and ventricular) inflated with gas during use. In addition to supporting the heart, replacing the work of the left ventricle in a permanent manner is also possible. Furthermore, the designed test stand makes it possible to carry out realistic experiments in an environment resembling a human heart. Exemplary pressure measurements for hypotension and hypertension conditions are presented.
Experimental Investigations of Forced Convection of Nanofluids in Smooth, Horizontal, Round Tubes: A Review
- Janusz Cieśliński
- Przemysław Kozak
2023 Pełny tekst ENERGIES
A comprehensive review of published works dealing with experimental studies of forced convection heat transfer of nanofluids is presented. The survey is limited to straight, smooth, and round tubes. Moreover, only mono nanofluids exhibiting Newtonian behaviour are considered. Works on experimental research of forced convection in tubes are presented in a chronological order in the first part of the article. In this part, attention was paid to the influence of nanoparticles on the intensification of heat transfer. Information on the tested nanofluids, the measurement technique used, and the measurement range are presented in tabular form. Correlation equations proposed by individual researchers are also presented. In order to explain the controversy regarding the different influences of nanoparticles on the intensity of heat transfer during forced convection of nanofluids, the second part of the paper presents a comparison of the test results obtained by different researchers for the same nanofluid, possibly under the same thermal and flow conditions. Finally, the main conclusions are discussed.
Experimental investigations on the mechanical properties and damage detection of carbon nanotubes modified crumb rubber concrete
- Suliman Khan
- Shahzad Ashraf
- Shehroze Ali
- Khushal Khan
2023 Pełny tekst Journal of Building Engineering
This study presents a modified crumb rubber (MCR) concrete design mix reinforced with multi-walled carbon nanotubes (MWCNTs), mechanical characterization, and cracking monitoring using the acoustic emission (AE) technique. The results showed that the bridging effect of MWCNTs and MCR in the concrete mix mitigated the shortcomings of MWCNT-MCR concrete and improved the flexural and compressive strengths by 18.3% and 26.5%, respectively, at 28 days. The stress-strain behavior of the MWCNT-MCR concrete showed improved ductility (48.12%), axial strain (50.12%), and toughness (27.15%) compared to the reference specimens. The MWCNT–MCR concrete exhibited a mechanical response in three distinct loading phases. Overall, tensile failure (>4000 μs/v and >35 kHz) was observed in the tested specimens through the RA value (ratio of rise time to amplitude of AE waves) and average frequency (AF) distribution. Based on the amplitude distribution of the AE waves, the damping capacity of the MWCNT-MCR concrete was improved by 27.83%, and the fracture mechanism between micro and macro cracks was identified through a b-value approach. Finally, a regression model was established to predict the Ec of MWCNT-MCR concrete and the two-way interaction effect on the mechanical properties of the developed mix design.
Experimental review of the performances of protective coatings for interconnects in solid oxide fuel cells
- Mareddy Jayanth Reddy
- Bartosz Kamecki
- Belma Talic
- Elisa Zanchi
- Federico Smeacetto
- John S. Hardy
- Jung Choi Choi
- Łukasz Mazur
- Robert Vaßen
- Soumendra N. Basu
- Tomasz Brylewski
- Jan-Erik Svensson
- Jan Froitzheim
2023 Pełny tekst JOURNAL OF POWER SOURCES
Ferritic stainless steel interconnects are used in solid oxide fuel cells; however, coatings are required to improve their performance. Although several types of coatings have been proposed, they have been scarcely investigated under similar conditions. This study compares the characteristics of uncoated Crofer 22 APU and eight different coatings on Crofer 22 APU for up to 3000 h at 800 ◦C. The coatings were deposited at various research laboratories around the world, and the experiments were performed at Chalmers University of Technology, Sweden. Cross-sections of the samples were analysed using scanning electron microscopy and energy-dispersive x-ray spectroscopy. The (Co,Mn)-based coated steels showed more than 50-fold lower chromium evaporation and at least 3 times thinner Cr2O3 scale thickness compared to uncoated steel. The coated steel samples showed lower area-specific resistance (ASR) values than the uncoated steel after 3000 h of exposure, irrespective of the coating thickness, composition and deposition method.