1,909 research outputs found
Dynamic analysis and energy management strategies of micro gas turbine systems integrated with mechanical, electrochemical and thermal energy storage devices
The growing concern related to the rise of greenhouse gases in the atmosphere has led to an increase of share of renewable energy sources. Due to their unpredictability and intermittency, new flexible and efficient power systems need to be developed to compensate for this fluctuating power production. In this context, micro gas turbines have high potential for small-scale combined heat and power (CHP) applications considering their fuel flexibility, quick load changes, low maintenance, low vibrations, and high overall efficiency. Furthermore, the combination of micro gas turbines with energy storage systems can further increase the overall system flexibility and the response to rapid load changes. This thesis aims to analyse the integration of micro gas turbines with the following energy storage systems: compressed air energy storage (CAES), chemical energy storage (using hydrogen and ammonia), battery storage, and thermal energy storage.
In particular, micro gas turbines integrated with CAES systems and alternative fuels operate in different working conditions compared to their standard conditions. Applications requiring increased mass flow rate at the expander, such as CAES and the use of fuels with low LHV, such as ammonia, can potentially reduce the compressor surge margin. Conversely, sudden composition changes of high LHV fuels, such as hydrogen, can cause temperature peaks, detrimental for the turbine and recuperator life. A validated model of a T100 micro gas turbine is used to analyse transitions between different conditions, identify operational limits and test the control system.
Starting from the dynamic constraints defined in the related chapters, in the final part, an optimisation tool for energy management is developed to couple the micro gas turbine with energy storage systems, maximizing the plant profitability and satisfying the local electrical and thermal demands. For the modelling of the CAES system and alternative fuels, the operating constraints obtained from the initial analyses are implemented in the optimisation tool. In addition, a battery and thermal energy storage system are also considered.
In the first part, a comprehensive analysis of the T100 combined with a second-generation CAES system showed enhanced efficiency, reduced fuel consumption, reduced thermal power output and increased maximum electrical power output due to the reduction of the rotational speed. The study identified optimal air injection constraints, demonstrating a +3.23% efficiency increase at 80 kW net power with a maximum mass flow rate of 50 g/s. The dynamic analysis exposed potential instabilities issues during air step injections, mitigated by using ramps at a rate of +0.5 (g/s)/s for safe and rapid dynamic mode operation. The second part explored the effects of varying H2-NG and NH3-NG blends on the T100 mGT. Steady-state results showed increased power output with hydrogen or ammonia, notably +6.1 kW for 100% H2 and up to +11.3 kW for 100% NH3. Transient power steps simulations showed surge margin reductions, especially at lower power levels with high concentrations of ammonia, highlighting the need for controlled transitions. Controlled ramps were effective in preventing extreme temperature peaks during fuel composition changes. The final chapter focused on developing an energy scheduler for different plant setups, evaluating four configurations. For a typical day of the month of April of the Savona Campus, the integration of the CAES lead to relative savings of +8.1% and power-to-H2 of +5.3% when surplus electricity was not sold to the grid. Conversely, with the ability to sell excess electricity, CAES and battery energy storage (BES) systems exhibit modest savings of +1.2% and +2.4%, respectively, while the power-to-H2 system failed to provide economic advantages
Natural and Technological Hazards in Urban Areas
Natural hazard events and technological accidents are separate causes of environmental impacts. Natural hazards are physical phenomena active in geological times, whereas technological hazards result from actions or facilities created by humans. In our time, combined natural and man-made hazards have been induced. Overpopulation and urban development in areas prone to natural hazards increase the impact of natural disasters worldwide. Additionally, urban areas are frequently characterized by intense industrial activity and rapid, poorly planned growth that threatens the environment and degrades the quality of life. Therefore, proper urban planning is crucial to minimize fatalities and reduce the environmental and economic impacts that accompany both natural and technological hazardous events
The Development of Microdosimetric Instrumentation for Quality Assurance in Heavy Ion Therapy, Boron Neutron Capture Therapy and Fast Neutron Therapy
This thesis presents research for the development of new microdosimetric instrumentation for use with solid-state microdosimeters in order to improve their portability for radioprotection purposes and for QA in various hadron therapy modalities. Monte Carlo simulation applications are developed and benchmarked, pertaining to the context of the relevant therapies considered. The simulation and experimental findings provide optimisation recommendations relating to microdosimeter performance and possible radioprotection risks by activated materials.
The first part of this thesis is continuing research into the development of novel Silicon-on-Insulator (SOI) microdosimeters in the application of hadron therapy QA. This relates specifically to the optimisation of current microdosimeters, development of Monte Carlo applications for experimental validation, assessment of radioprotection risks during experiments and advanced Monte Carlo modelling of various accelerator beamlines.
Geant4 and MCNP6 Monte Carlo codes are used extensively in this thesis, with rigorous benchmarking completed in the context of experimental verification, and evaluation of the similarities and differences when simulating relevant hadron therapy facilities.
The second part of this thesis focuses on the development of a novel wireless microdosimetry system - the Radiodosimeter, to improve the operation efficiency and minimise any radioprotection risks. The successful implementation of the wireless Radiodosimeter is considered as an important milestone in the development of a microdosimetry system that can be operated by an end-user with no prior knowledge
Introduction to Psychology
Introduction to Psychology is a modified version of Psychology 2e - OpenStax
GREEN INVESTMENT OPTIONS IN FERRY, RO-RO AND RO-PAX INDUSTRY - From theory to practice
An increased focus on sustainability issues and climate change from customers as well as the whole society, jointly with more restrictive regulatory requirements, are triggering shipping lines to progressively adopt green strategies, aiming at reducing emissions and pursuing higher (energy) efficiency standards (Pallis and Vaggelas, 2019). In the shipping sector, the Ferry segment expresses global fleet of about 15,400 ships with a total gross tonnage (GT) exceeding 31 million, and globally transports about 4.27 billion passengers per year and 373 million vehicles; furthermore, it has a contribution on world GDP of 60 billion dollars and allows the employment of more than 1 million people (Interferry, 2019). Because of the importance of the traffic volumes handled both in terms of passengers and cargoes, as well as due to the related impacts originating from business operations, the Ferry, Ro-Ro and Ro-Pax industry is challenged to implement green strategies (Chang and Danao, 2007). Corporate Social Responsibility (CSR) paradigms and related theoretical constructs are expected to reshape future goals, strategies and implantation trajectories of major Ferry, Ro-Ro and Ro-Pax companies and improve firm performance (Lun et al., 2015). This PhD thesis scrutinizes green strategies and related investment options which are expected to allow Ferry, Ro-Ro and Ro-Pax group owners, operating European-flagged vessels, to reach sustainability goals without negatively affecting their economic/financial performance.
The document proposes a conceptual framework that addresses the most promising green investment options which Ferry, Ro-Ro and Ro-Pax companies can exploit for making the business more sustainable, reducing environmental impacts and improving energy and material efficiency during day-by-day operations. Using insights from a systematic literature review conducted in the first sections of this PhD thesis, the most relevant green solutions widely investigated at academic level are examined and discussed for the purpose of this PhD thesis.
After an exhaustive description of the state of the art and the state of the play regarding green investment options in Ferry, Ro-Ro and Ro-Pax industry, this PhD thesis proposes an analysis of the most effective green strategies and practices concretely developed and planned in the industry. Empirical evidence shows that the most promising investment options relate to ship propulsion systems, such as the adoption of hydrogen and fuel cells (Trillos et al., 2021), alternative fuels (Very Low Sulphur Fuel Oil, Ultra Low Sulphur Fuel Oil and Liquefied Natural Gas), efficiency systems for auxiliary engines and ship design solutions. As confirmed by outcomes gathered in our final empirical dataset, i.e., the “green” sample, among the different solutions analysed, the most adopted green investment options by European companies operating in Ferry, Ro-Ro and Ro-Pax industry are: a) the refitting of bulbous bow, aimed at the implementation of the current design of the hull to increase the overall hydrodynamics of the ship; b) the installation of onboard batteries as a source of energy for ship propulsion; c) the use of Liquefied Natural Gas (LNG) as alternative fuel for the ship propulsion, that contributes to a 100% reduction in sulphur oxides emissions, 80-85% of nitrogen oxides emissions, 95% of particular matter emissions and 20-30% of carbon dioxide emissions compared to HFO/MDO (Burel et al., 2013).
The empirical analysis above mentioned is performed on 1,680 Ferry, Ro-Ro and Ro-Pax ships with flag from European Countries, with data gathered through IHS Maritime & Trade that holds the largest maritime ships database in the world, further integrated with data and information collected from several technical sources (e.g., news press, sustainability report and press release of European companies). Variables investigates within IHS Maritime & Trade regard the type of main and auxiliary engines and fuel type, hull materials, bulbous bow and other technologies and equipment aimed at mitigating the pollution and reducing harmful emissions. The outcomes shed light on the viability and feasibility of some green investments options by shipping companies operating in Ferry, Ro-Ro and Ro-Pax industry at European level.
To deal with this limited result, due to the lack of comprehensive dataset capable to scrutinize the diverse green solutions implemented on board European-flagged vessels, it was decided to develop an original and detailed dataset, capable to provide additional information concerning the approaches, decisions and strategies adopted by each group owners and related future trends about the adoption of green strategies in the sector. Through the examination of different sources (e.g., news press, specialised journals, communications by the companies on their corporate website, academic papers, etc.), information related to innovative technical solutions and cutting-edge technologies for mitigating the pollution and reducing harmful emissions have been extracted for each ship of the database, i.e., the “overall” or “extended” sample. In this way, it has been possible to provide an exhaustive overview of the heterogeneous green solutions, equipment and components installed on board of ships that are part of the “green” sample and the related source, to allow the evaluation and examination from the point of view of the institutionalism of the source. In this way it was possible to focus on top ten best performer group owners of the “green” sample, to analyse the managerial and governance behaviours and attitudes implemented by them and to deepen in brief case histories the main strategies adopted by them
Neutron scattering studies of heterogeneous catalysis
Understanding the structural dynamics/evolution of catalysts and the related surface chemistry is essential for establishing structure–catalysis relationships, where spectroscopic and scattering tools play a crucial role. Among many such tools, neutron scattering, though less-known, has a unique power for investigating catalytic phenomena. Since neutrons interact with the nuclei of matter, the neutron–nucleon interaction provides unique information on light elements (mainly hydrogen), neighboring elements, and isotopes, which are complementary to X-ray and photon-based techniques. Neutron vibrational spectroscopy has been the most utilized neutron scattering approach for heterogeneous catalysis research by providing chemical information on surface/bulk species (mostly H-containing) and reaction chemistry. Neutron diffraction and quasielastic neutron scattering can also supply important information on catalyst structures and dynamics of surface species. Other neutron approaches, such as small angle neutron scattering and neutron imaging, have been much less used but still give distinctive catalytic information. This review provides a comprehensive overview of recent advances in neutron scattering investigations of heterogeneous catalysis, focusing on surface adsorbates, reaction mechanisms, and catalyst structural changes revealed by neutron spectroscopy, diffraction, quasielastic neutron scattering, and other neutron techniques. Perspectives are also provided on the challenges and future opportunities in neutron scattering studies of heterogeneous catalysis
Systemic Circular Economy Solutions for Fiber Reinforced Composites
This open access book provides an overview of the work undertaken within the FiberEUse project, which developed solutions enhancing the profitability of composite recycling and reuse in value-added products, with a cross-sectorial approach. Glass and carbon fiber reinforced polymers, or composites, are increasingly used as structural materials in many manufacturing sectors like transport, constructions and energy due to their better lightweight and corrosion resistance compared to metals. However, composite recycling is still a challenge since no significant added value in the recycling and reprocessing of composites is demonstrated. FiberEUse developed innovative solutions and business models towards sustainable Circular Economy solutions for post-use composite-made products. Three strategies are presented, namely mechanical recycling of short fibers, thermal recycling of long fibers and modular car parts design for sustainable disassembly and remanufacturing. The validation of the FiberEUse approach within eight industrial demonstrators shows the potentials towards new Circular Economy value-chains for composite materials
Accurate Battery Modelling for Control Design and Economic Analysis of Lithium-ion Battery Energy Storage Systems in Smart Grid
Adoption of lithium-ion battery energy storage systems (Li-ion BESSs) as a flexible energy source (FES) has been rapid, particularly for active network management (ANM) schemes to facilitate better utilisation of inverter based renewable energy sources (RES) in power systems. However, Li-ion BESSs display highly nonlinear performance characteristics, which are based on parameters such as state of charge (SOC), temperature, depth of discharge (DOD), charge/discharge rate (C-rate), and battery-aging conditions. Therefore, it is important to include the dynamic nature of battery characteristics in the process of the design and development of battery system controllers for grid applications and for techno-economic studies analyzing the BESS economic profitability.
This thesis focuses on improving the design and development of Li-ion BESS controllers for ANM applications by utilizing accurate battery performance models based on the second-order equivalent-circuit dynamic battery modelling technique, which considers the SOC, C-rate, temperature, and aging as its performance affecting parameters. The proposed ANM scheme has been designed to control and manage the power system parameters within the limits defined by grid codes by managing the transients introduced due to the intermittence of RESs and increasing the RES penetration at the same time. The validation of the ANM scheme and the effectiveness of controllers that manage the flexibilities in the power system, which are a part of the energy management system (EMS) of ANM, has been validated with the help of simulation studies based on an existing real-life smart grid pilot in Finland, Sundom Smart Grid (SSG). The studies were performed with offline (short-term transient-stability analysis) and real-time (long-term transient analysis) simulations.
In long-term simulation studies, the effect of battery aging has also been considered as part of the Li-ion BESS controller design; thus, its impact on the overall power system operation can be analyzed. For this purpose, aging models that can determine the evolving peak power characteristics associated with aging have been established. Such aging models are included in the control loop of the Li-ion BESS controller design, which can help analyse battery aging impacts on the power system control and stability. These analyses have been validated using various use cases. Finally, the impact of battery aging on economic profitability has been studied by including battery-aging models in techno-economic studies.Aurinkosähköjärjestelmien ja tuulivoiman laajamittainen integrointi sähkövoimajärjestelmän eri jännitetasoille on lisääntynyt nopeasti. Uusiutuva energia on kuitenkin luonteeltaan vaihtelevaa, joka voi aiheuttaa nopeita muutoksia taajuudessa ja jännitteessä. Näiden vaihteluiden hallintaan tarvitaan erilaisia joustavia energiaresursseja, kuten energiavarastoja, sekä niiden tehokkaan hyödyntämisen mahdollistaviea älykkäitä ja aktiivisia hallinta- ja ohjausjärjestelmiä.
Litiumioniakkuihin pohjautuvien invertteriliitäntäisten energian varastointijärjestelmien käyttö joustoresursseina aktiiviseen verkonhallintaan niiden pätö- ja loistehon ohjauksen avulla on lisääntynyt nopeasti johtuen niiden kustannusten laskusta, modulaarisuudesta ja teknisistä ominaisuuksista. Litiumioniakuilla on erittäin epälineaariset ominaisuudet joita kuvaavat parametrit ovat esimerkiksi lataustila, lämpötila, purkaussyvyys, lataus/ purkausnopeus ja akun ikääntyminen. Akkujen ominaisuuksien dynaaminen luonne onkin tärkeää huomioida myös akkujen sähköverkkoratkaisuihin liittyvien säätöjärjestelmien kehittämisessä sekä teknis-taloudellisissa kannattavuusanalyyseissa.
Tämä väitöstutkimus keskittyy ensisijaisesti aktiiviseen verkonhallintaan käytettävien litiumioniakkujen säätöratkaisuiden parantamiseen hyödyntämällä tarkkoja, dynaamisia akun suorituskykymalleja, jotka perustuvat toisen asteen ekvivalenttipiirien akkumallinnustekniikkaan, jossa otetaan huomioon lataustila, lataus/purkausnopeus ja lämpötila. Työssä kehitetyn aktiivisen verkonhallintajärjestelmän avulla tehtävät akun pätö- ja loistehon ohjausperiaatteet on validoitu laajamittaisten simulointien avulla, esimerkiksi paikallista älyverkkopilottia Sundom Smart Gridiä simuloimalla. Simuloinnit tehtiin sekä lyhyen aikavälin offline-simulaatio-ohjelmistoilla että pitkän aikavälin simulaatioilla hyödyntäen reaaliaikasimulointilaitteistoa.
Pitkän aikavälin simulaatioissa akun ikääntymisen vaikutus otettiin huomioon litiumioniakun ohjauksen suunnittelussa jotta sen vaikutusta sähköjärjestelmän kokonaistoimintaan voitiin analysoida. Tätä tarkoitusta varten luotiin akun ikääntymismalleja, joilla on mahdollista määrittää akun huipputehon muutos sen ikääntyessä. Akun huipputehon muutos taas vaikuttaa sen hyödynnettävyyteen erilaisten pätötehon ohjaukseen perustuvien joustopalveluiden tarjoamiseen liittyen. Lisäksi väitöstutkimuksessa tarkasteltiin akkujen ikääntymisen vaikutusta niiden taloudelliseen kannattavuuteen sisällyttämällä akkujen ikääntymismalleja teknis-taloudellisiin tarkasteluihin.fi=vertaisarvioitu|en=peerReviewed
Development of 3D printed enzymatic biofuel cells for powering implantable biomedical devices
The drive toward device miniaturisation in the field of enzyme-based bioelectronics established a need for multi-dimensional geometrically structured and highly effective microelectrodes, which are difficult to implement and manufacture in devices such as biofuel cells and sensors. Additive manufacturing coupled with electroless metal plating enables the production of three-dimensional (3D) conductive microarchitectures with high surface area for potential applications in such devices. However, interfacial delamination between the metal layer and the polymer structure is a major reliability concern, which results in device performance degradation and eventually device failure.
This thesis demonstrates a method to produce a highly conductive and robust metal layer on a 3D printed polymer microstructure with strong adhesion by introducing an interfacial adhesion layer. Prior to 3D printing, multifunctional acrylate monomers with alkoxysilane (-Si-(OCH3)3) were synthesised via the Thiol-Michael addition reaction between pentaerythritol tetraacrylate (PETA) and 3-mercaptopropyltrimethoxysilane (MPTMS) with a 1:1 stoichiometric ratio. Alkoxysilane functionality remains intact during photopolymerisation in a projection micro-stereolithography (PµSLA) system and is utilised for the sol-gel reaction with MPTMS post-functionalisation of the 3D printed microstructure to build an interfacial adhesion layer. This functionalisation leads to the implementation of abundant thiol functional groups on the surface of the 3D printed microstructure, which can act as a strong binding site for gold during electroless plating to improve interfacial adhesion. The 3D conductive microelectrode prepared by this technique exhibited excellent conductivity of 2.2×107 S/m (53% of bulk gold) with strong adhesion between a gold layer and a polymer structure even after harsh sonication and adhesion tape test, which offers potential to build a robust 3D conductive microarchitecture for applications such as biosensors and biofuel cells.
As a proof-of-concept, the microelectrode with gold-coated complex lattice geometry was employed as an enzymatic glucose anode, which showed a significant increase in the current output compared to the one in the simple cube form. As the first approach, glucose oxidase was used as an enzyme. To find the optimal protocol for the enzyme immobilisation, the enzyme was first immobilised on agarose to achieve the enzyme’s highest activity and stability. Then, this immobilisation protocol was applied to immobilise the enzyme on the gold electrode surface. Preliminary studies on the preparation of 3D gold diamond lattice microelectrode modified with cysteamine and glucose oxidase as a bioanode for single cell enzymatic biofuel cell (EFC) application were performed, which demonstrated high current density of 0.38 μA cm–2 at 0.35 V in glucose solutions.
This method for fabrication of 3D conductive microelectrodes offers potential for several biological applications. Instead of using a thiol, the surface of the 3D-printed part can be functionalised with different other functional groups to create an appropriate surface for biomolecules and cell adhesion. Furthermore, the surface of thiol functionalised printed parts can be perfect for additional metal coatings, opening the door to the creation of highly efficient and customised implantable energy harvesters and biosensors
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