29,594 research outputs found

    Rail power conditioners based on modular multilevel converter in AC railway networks

    No full text
    Programa doutoral em Engenharia Electr√≥nica e de ComputadoresRailway systems have progressively been developed since James Watt presented a technique of converting steam power into a circular movement back in 1763. With the novelty of steam engines at that time and the increasing of railway networks, railway industry quickly became an economic catalyst throughout the world due to the advantages of passenger and freight transport. In 1879, Siemens & Halske company introduced the world‚Äôs first electric train in the city of Berlin, consisting of a locomotive and three wagons, and supplied via an insulated third rail with 150 V direct current (DC). From that time, the world has begun to recognize the important transition from steam power to electric power, and the potential of the electrified railway as a mode of mass transport. Due to the plenty of fuel in the last century, Diesel trains were not only common, but they also dominated the railway sector for a few decades. Consequently, the development in the infrastructures of electric trains decelerated, and the path to having fully electrified trains was long enough. In this context, electric trains have introduced progressively, in which Diesel and electric power have been combined to create hybrid locomotives. However, and with the increased demand for transportation and the higher fuel prices in the last decades, electric trains can substantially offer lower operating costs and lower emissions compared with the Diesel-powered trains. Nowadays, most of the high-speed electric trains use alternating current (AC) power supply for their traction power systems, which provide better performance under long-distance power transmission than DC power supply. However, as the need for railway transportation increases due to more passengers and higher mobility requirements, more flexible and efficient traction systems are always needed. In Europe, AC traction power systems are mainly classified according to the voltage and frequency parameters (15 kV, 16.7 Hz) or (1√ó25 kV or 2√ó25 kV, 50 Hz). In all cases, railway operators have an absolute interest to run the electrified trains with the lowest possible operation and maintenance costs. In this context, power quality improvement at the three-phase power grid, associated with the AC electrified railway has drawn more attention in the last decades, especially after the evolution in the Power Electronics field. Subsequently, various solutions based on Power Electronics converters have been proposed to improve power quality in the electrified railway, e.g., the flexible AC transmission systems (FACTS). The rail power conditioner (RPC) is one of the FACTS devices that can be used to improve power quality by compensating harmonic contents, reactive power and negative sequence components of currents generated by the railway system. Among the other possible multilevel power converters, the modular multilevel converter (MMC) is an attractive solution for medium-voltage applications due to harmonics reduction, lower switching losses, and higher flexibility, scalability and reliability. Therefore, the MMC has been enhanced to be combined with the FACTS family. Taking into consideration the existing opportunities in the railway industry, not only in the development of the electric train itself, but also on the power quality improvement in the electrified railway, there is a strong investment in technological development for electrified railway systems. Therefore, this work presents a new topology of Power Electronics converter (RPC based on MMC) that compensates power quality problems associated with traction power systems, thus, reducing the operating costs of the electrified trains and increasing the power capacity of the electric traction grid. The main innovations of the RPC based on MMC are the integration of the MMC topology to operate as a railway power quality conditioner, benefiting from the advantages of the MMC in the traction power supply system. In this context, the research work proposed and developed in this Ph.D. thesis aimed to design, develop and validate a reduced-scale laboratory prototype of the RPC based on MMC, including all the necessary control algorithms and simulation models that are important to support the correct operation of the proposed system. Under simulation conditions, this work developed control algorithms for different RPC topologies, (full-bridge, half-bridge, three-wire, etc.) for demonstrating the general capabilities of the RPC system, and also for two different transformers connections (V/V and Scott). The most favorable RPC based on MMC topology (based on half-bridge MMC) was deeply and extensively simulated, namely employing predictive control approach. The experimental results obtained from a developed reduced-scale prototype confirm the validity of the presented control theory, as well as the power quality improvement capability of the proposed solution.Os sistemas ferrovias foram progressivamente desenvolvidos desde que James Watt apresentou uma t√©cnica de convers√£o da energia a vapor para um movimento circular em 1763. Com a novidade dos motores a vapor e a sua implementa√ß√£o nas redes ferrovi√°rias, a ind√ļstria ferrovi√°ria rapidamente se tornou um catalisador econ√īmico em todo o mundo devido √†s vantagens no transporte de passageiros e mercadorias. Em 1879, a empresa Siemens & Halske introduziu o primeiro comboio el√©trico do mundo na cidade de Berlim, consistindo numa locomotiva com tr√™s vag√Ķes, alimentado por um terceiro trilho isolado alimentado com corrente cont√≠nua em 150 V (CC). A partir desse momento, o mundo come√ßou a reconhecer a importante transi√ß√£o da energia a vapor para a energia el√©trica e o potencial na ferrovia eletrificada como um meio de transporte de massa. Devido √† abund√Ęncia de combust√≠vel f√≥ssil no s√©culo passado, os comboios a Diesel n√£o eram apenas comuns, mas tamb√©m dominaram o setor ferrovi√°rio. Consequentemente, o desenvolvimento das infraestruturas dos comboios el√©tricos desacelerou, e o caminho para haver comboios totalmente eletrificados tornou-se bastante longo. Nesse contexto, os comboios el√©tricos come√ßaram a impor-se progressivamente, inicialmente pela combina√ß√£o do motor Diesel e do motor el√©trico, resultando numa locomotiva h√≠brida. No entanto, com o aumento da demanda pelo transporte, e com o aumento do pre√ßo dos combust√≠veis nas √ļltimas d√©cadas, os comboios el√©tricos afirmaram-se por poderem oferecer custos operacionais mais baixos, assim como melhor desempenho ambiental. Atualmente, a maioria dos comboios el√©tricos de alta velocidade utilizam sistema de tra√ß√£o em corrente alternada (CA), que oferece melhor desempenho na transmiss√£o de energia a longa dist√Ęncia do que sistema de tra√ß√£o em corrente cont√≠nua CC. No entanto, o aumento do transporte ferrovi√°rio requer a melhoria da efici√™ncia energ√©tica devido a haver mais passageiros e maiores requisitos de mobilidade. Na Europa, os sistemas de tra√ß√£o el√©trica s√£o classificados principalmente de acordo com os par√Ęmetros de tens√£o e frequ√™ncia (15 kV, 16,7 Hz) ou (1√ó25 kV ou 2√ó25 kV, 50 Hz). Em ambos os casos, os operadores ferrovi√°rios t√™m interesse absoluto em otimizar os custos. Nesse contexto, a melhoria da qualidade de energia el√©trica na ferrovia suscitou mais aten√ß√£o nas √ļltimas d√©cadas, principalmente pela introdu√ß√£o da eletr√īnica de pot√™ncia. Posteriormente, v√°rias solu√ß√Ķes baseadas em conversores de eletr√īnica de pot√™ncia foram propostas para melhorar a qualidade de energia el√©trica na ferrovia, como por exemplo, os sistemas flex√≠veis de transmiss√£o CA (FACTS ‚Äď Flexible AC Transmission Systems). O condicionador ativo de pot√™ncia ferrovi√°rio (RPC ‚Äď Rail Power Conditioner) √© um dos dispositivos FACTS que pode ser usado para melhorar a qualidade da energia el√©trica, compensando o conte√ļdo harm√īnico, a pot√™ncia reativa e os componentes de sequ√™ncia negativa das correntes. Por outro lado, o conversor multin√≠vel modular (MMC ‚Äď Modular Multilevel Converter) √© uma solu√ß√£o atraente para aplica√ß√Ķes de m√©dia tens√£o, devido √† redu√ß√£o dos harm√≥nicos e das perdas de comuta√ß√£o, e ao aumento da flexibilidade, confiabilidade e escalabilidade. Deste modo, o MMC foi aprimorado para ser integrado na fam√≠lia FACTS. Levando em considera√ß√£o as oportunidades existentes no setor ferrovi√°rio, n√£o apenas no desenvolvimento do pr√≥prio comboio el√©trico, mas tamb√©m na melhoria da qualidade de energia el√©trica na ferrovia, existe um forte investimento no desenvolvimento tecnol√≥gico para os sistemas ferrovi√°rios eletrificados. Assim sendo, este trabalho apresenta uma nova topologia de conversor de eletr√īnica de pot√™ncia (RPC baseado em MMC) que compensa os problemas de qualidade de energia el√©trica associados aos sistemas de tra√ß√£o, reduzindo os custos operacionais dos comboios el√©tricos e otimizando a qualidade de energia da rede el√©trica. As inova√ß√Ķes principais do RPC baseado em MMC s√£o a integra√ß√£o da topologia do MMC para operar como condicionador de qualidade de energia el√©trica na ferrovia, beneficiando das vantagens do MMC. Neste contexto, o trabalho de investiga√ß√£o proposto e desenvolvido nesta tese apontou como objetivo projetar, desenvolver e validar um prot√≥tipo laboratorial em escala reduzida do RPC baseado em MMC, incluindo todos os algoritmos de controlo necess√°rios e os modelos de simula√ß√£o que s√£o importantes para suportar a opera√ß√£o correta do sistema. Sob condi√ß√Ķes de simula√ß√£o, este trabalho desenvolveu algoritmos de controlo para diferentes topologias do RPC (ponte completa, meia ponte, tr√™s fios, etc.), para demonstrar as capacidades gerais do sistema do RPC, e tamb√©m para dois transformadores diferentes (V/V e Scott). O RPC mais favor√°vel baseado na topologia do MMC (baseado no MMC de meia ponte) foi profunda e extensivamente simulado, nomeadamente utilizando uma abordagem de controlo preditivo. As simula√ß√Ķes e os resultados experimentais confirmam a validade da teoria de controlo apresentada, bem como a capacidade de melhoria da qualidade de energia el√©trica na solu√ß√£o proposta.Funda√ß√£o para a Ci√™ncia e a Tecnologia ‚Äď FCT), which allowed me to continue my studies with the PD/BD/127815/2016 Ph.D. scholarship under the Innovation in Railway Systems and Technologies Doctoral Program ‚Äď iRail

    Numerical modelling of the combustion process of e-fuel polyoxymethylene dimethyl ether

    No full text
    Kako bi se zadovoljili propisi za smanjenje ugljińćnog dioksida, ugljińćno neutralna sintetińćka goriva privlańće sve viŇ°e pozornosti kao alternative fosilnim gorivima. Posebna vrsta goriva koje se moŇĺe primijeniti u postojeńáe motore s unutarnjim izgaranjem i pokazuje slińćne karakteristike izgaranja kao i konvencionalna goriva, je polioksimetilen dimetil eter (OME). Rańćunalna dinamika fluida ńćesto se koristi za procjenu i ispitivanje svojstava novih goriva, ukljuńćujuńái sintetska goriva. U ovom radu dan je pregled sintetskih goriva i tehnologija sinteze, s naglaskom na trioksimetilen dimetil eter OME-3. Nadalje, numerińćka simulacija procesa izgaranja s ovim sintetskim gorivom provedena je u rańćunalnom softveru za dinamiku fluida AVL FIRE‚ĄĘ. Simulacija s OME-3 gorivom je usporeńĎena s rezultatima simulacija koje su koristile n-heptan kao gorivo i validirana eksperimentalnim podacima koje je ustupio AVL GmbH Graz. Za simulacije s OME-3 koriŇ°tena je kemijska kinetika i model izgaranja za usporedbu rezultata. Dva sluńćaja, od kojih je jedan sluńćaj s jednim ubrizgavanjem, a drugi sluńćaj s viŇ°e ubrizgavanja goriva, koriŇ°tena su u 3 razlińćita reŇĺima ubrizgavanja kako bi se procijenilo izgaranje sintetskog goriva OME-3 naspram n-heptana, koje je predstavljalo zamjenu za dizel gorivo. Promjenom profila ubrizgavanja i ubrizgane mase goriva OME-3 postignuti su rezultati u skladu s konvencionalnim gorivom.In order to meet the reductions of carbon dioxide, carbon-neutral synthetic fuels are drawing attention as an alternative to fossil fuels. One particular fuel, which can be implemented in existing internal combustion engines and shows similar combustion characteristics as conventional fuels, is polyoxymethylene dimethyl ether (OME). Computational fluid dynamics is often used to assess and test the properties of new fuels, including e-fuels. In this work, an overview of e-fuels and synthesis technologies is given, with an emphasis on OME-3. Furthermore, a numerical simulation of the combustion process with this e-fuel was conducted in the computational fluid dynamics software AVL FIRE‚ĄĘ. The simulation was verified by comparing the simulation data for n-heptane as fuel and validated with experimental data provided by AVL GmbH Graz. For the simulations with OME-3, both chemical kinetics and a combustion model were used to compare results. Two cases, one being a single injection case, the other being a multi-injection case, were used in 3 different injection regimes to assess how e-fuel OME-3 compares to n-heptane fuel, which is a substitute for diesel fuel. By varying the injection profile and injected mass of fuel of OME-3, results which were more comparable to conventional fuel were achieved

    Characterization from Diesel and Renewable Fuel Engine Exhaust: Particulate Size/Mass Distributions and Optical Properties

    Get PDF
    Combustion of fossil fuel produces emissions and is one of the major environmental problems leading to climate change. Diesel engines are highly efficient but produce particulate emissions. These particulate emissions are considered dangerous to human health because inhaling particulates may cause respiratory and heart disease. Substituting fossil diesel fuel with renewable diesel fuel and using diesel particulate filters is one possibility to meet stringent legislative requirements. With this motivation, the present experimental investigation aimed to evaluate the particle size distribution (PSD), optical properties of particulate matter (PM) emitted, and the outcome of using an after-treatment system comprising of a diesel particle filter (DPF). This investigation aimed to make a comparative analysis of particulate emission upstream and downstream of the DPF with and without ultraviolet (UV) light (405\ua0nm and 781\ua0nm wavelength) turned on/off. Experiments were performed at (a) engine idle with a torque of 6 Nm at 750\ua0rpm, IMEP of 1.35\ua0bar and power of 0.5\ua0kW, (b) engine at part load with a torque of 32 Nm at 1200\ua0rpm, IMEP of 8.5\ua0bar and power of 4.5\ua0kW. Diesel engine was operated on two fuels (a) Diesel and (b) EHR7. Results showed that as and when UV light was turned on, a distinct nucleation mode that dominated the number concentration for both test fuels were observed. Downstream of the filter had relatively higher AAE values which show the contribution to climate change. Present experimental research is important for renewable fuel industries, industrial innovation\u27s future, and the exhaust gas after-treatment system (EATS) community. The results contribute to knowledge for occupational exposure, human health, and the environment

    Effect of Acetic Acid and/or Sodium Hydroxide Treatment towards Characters of Wonosari Natural Zeolite for Hydrotreatment of Castor Oil into Biofuel

    Get PDF
    Natural zeolite (ZA) obtained from Wonosari, Indonesia, was treated with acetic acid (ZAA) or NaOH (ZAB), and the combination of both treatments (ZAAB) in order to increase the Si/Al ratio and catalytic performance on hydrotreatment of castor oil. The Si/Al ratio of ZA increased after the combination of acetic acid and NaOH treatment. The change of the Si/Al ratio was observed in the FTIR spectra as the shifting of internal asymmetric stretching vibration of T‚ąíO‚ąíT at 1032-1100 cm‚ąí1. The XRD profile of ZA was maintained after being subjected to treatments, and ZAB exhibited the lowest crystallinity. The surface area of the ZA after treatment is in the order ZAA¬†<¬†ZA¬†< ZAAB¬†<¬†ZAB. The ZAB catalyst having the highest surface area (19.144 m2 g‚ąí1) showed the highest catalytic activity on the hydrotreatment of castor oil with a liquid fraction of 55.1 wt.% and selectivity towards the hydrocarbon compounds of 22.40 wt.%

    Financing Low-Carbon Transport Transition in the Philippines: Mapping Financing Sources, Gaps and Directionality of Innovation

    Get PDF
    Successfully achieving a low-carbon transition in the transport sector requires an understanding of the lending logics of the financial institutions in order to identify the financing directionality and gaps. However, in the transportation literature, there is a lack of attention on the relationship between financing sources and the direction of innovation. The present study seeks to address this by mapping the flow of finance from financial institutions to transport projects. Our dataset consists of 9 transport projects included in the Philippines‚Äô Nationally Determined Contribution (NDC). We consider different types of projects (rail development, bus rapid transit implementation, jeepney modernization) and various financial actors (multi-lateral banks, private and government banks). Through an analysis of loan portfolio composition and interview data, we uncover the underlying logics of each financial institution in lending to transport projects. Our findings suggest that the lending logics of many financial institutions is primarily driven by portfolio and borrower credit-worthiness considerations, and less by motivations concerning sustainability transition. As a result, with respect to the average, some transport projects are over-financed (e.g. rail development), while others ‚Äď which have a high potential to accelerate decarbonization ‚Äď are under-financed (e.g. jeepney modernization). All these have profound implications for the directionality of low-carbon transition. Deeper engagement of transition research with finance is a nascent field, and the current research contributes to the literature not only by presenting a comprehensive mapping of several financing sources and projects, but also of proposing three credit enhancement mechanisms to mobilize capital for under-financed projects

    Gasificação direta de biomassa para produção de gás combustível

    Get PDF
    The excessive consumption of fossil fuels to satisfy the world necessities of energy and commodities led to the emission of large amounts of greenhouse gases in the last decades, contributing significantly to the greatest environmental threat of the 21st century: Climate Change. The answer to this man-made disaster is not simple and can only be made if distinct stakeholders and governments are brought to cooperate and work together. This is mandatory if we want to change our economy to one more sustainable and based in renewable materials, and whose energy is provided by the eternal nature energies (e.g., wind, solar). In this regard, biomass can have a main role as an adjustable and renewable feedstock that allows the replacement of fossil fuels in various applications, and the conversion by gasification allows the necessary flexibility for that purpose. In fact, fossil fuels are just biomass that underwent extreme pressures and heat for millions of years. Furthermore, biomass is a resource that, if not used or managed, increases wildfire risks. Consequently, we also have the obligation of valorizing and using this resource. In this work, it was obtained new scientific knowledge to support the development of direct (air) gasification of biomass in bubbling fluidized bed reactors to obtain a fuel gas with suitable properties to replace natural gas in industrial gas burners. This is the first step for the integration and development of gasification-based biorefineries, which will produce a diverse number of value-added products from biomass and compete with current petrochemical refineries in the future. In this regard, solutions for the improvement of the raw producer gas quality and process efficiency parameters were defined and analyzed. First, addition of superheated steam as primary measure allowed the increase of H2 concentration and H2/CO molar ratio in the producer gas without compromising the stability of the process. However, the measure mainly showed potential for the direct (air) gasification of high-density biomass (e.g., pellets), due to the necessity of having char accumulation in the reactor bottom bed for char-steam reforming reactions. Secondly, addition of refused derived fuel to the biomass feedstock led to enhanced gasification products, revealing itself as a highly promising strategy in terms of economic viability and environmental benefits of future gasification-based biorefineries, due to the high availability and low costs of wastes. Nevertheless, integrated techno economic and life cycle analyses must be performed to fully characterize the process. Thirdly, application of low-cost catalyst as primary measure revealed potential by allowing the improvement of the producer gas quality (e.g., H2 and CO concentration, lower heating value) and process efficiency parameters with distinct solid materials; particularly, the application of concrete, synthetic fayalite and wood pellets chars, showed promising results. Finally, the economic viability of the integration of direct (air) biomass gasification processes in the pulp and paper industry was also shown, despite still lacking interest to potential investors. In this context, the role of government policies and appropriate economic instruments are of major relevance to increase the implementation of these projects.O consumo excessivo de combust√≠veis f√≥sseis para garantir as necessidades e interesses da sociedade conduziu √† emiss√£o de elevadas quantidades de gases com efeito de estufa nas √ļltimas d√©cadas, contribuindo significativamente para a maior amea√ßa ambiental do s√©culo XXI: Altera√ß√Ķes Clim√°ticas. A solu√ß√£o para este desastre de origem humana √© de car√°ter complexo e s√≥ pode ser atingida atrav√©s da coopera√ß√£o de todos os governos e partes interessadas. Para isto, √© obrigat√≥ria a cria√ß√£o de uma bioeconomia como base de um futuro mais sustent√°vel, cujas necessidades energ√©ticas e materiais sejam garantidas pelas eternas energias da natureza (e.g., vento, sol). Neste sentido, a biomassa pode ter um papel principal como uma mat√©ria prima ajust√°vel e renov√°vel que permite a substitui√ß√£o de combust√≠veis f√≥sseis num variado n√ļmero de aplica√ß√Ķes, e a sua convers√£o atrav√©s da gasifica√ß√£o pode ser a chave para este prop√≥sito. Afinal, na pr√°tica, os combust√≠veis f√≥sseis s√£o apenas biomassa sujeita a elevada temperatura e press√£o durante milh√Ķes de anos. Al√©m do mais, a gest√£o eficaz da biomassa √© fundamental para a redu√ß√£o dos riscos de inc√™ndio florestal e, como tal, temos o dever de utilizar e valorizar este recurso. Neste trabalho, foi obtido novo conhecimento cient√≠fico para suporte do desenvolvimento das tecnologias de gasifica√ß√£o direta (ar) de biomassa em leitos fluidizados borbulhantes para produ√ß√£o de g√°s combust√≠vel, com o objetivo da substitui√ß√£o de g√°s natural em queimadores industriais. Este √© o primeiro passo para o desenvolvimento de biorrefinarias de gasifica√ß√£o, uma potencial futura ind√ļstria que ir√° providenciar um variado n√ļmero de produtos de valor acrescentado atrav√©s da biomassa e competir com a atual ind√ļstria petroqu√≠mica. Neste sentido, foram analisadas v√°rias medidas para a melhoria da qualidade do g√°s produto bruto e dos par√Ęmetros de efici√™ncia do processo. Em primeiro, a adi√ß√£o de vapor sobreaquecido como medida prim√°ria permitiu o aumento da concentra√ß√£o de H2 e da raz√£o molar H2/CO no g√°s produto sem comprometer a estabilidade do processo. No entanto, esta medida somente revelou potencial para a gasifica√ß√£o direta (ar) de biomassa de alta densidade (e.g., pellets) devido √† necessidade da acumula√ß√£o de carbonizados no leito do reator para a ocorr√™ncia de rea√ß√Ķes de reforma com vapor. Em segundo, a mistura de combust√≠veis derivados de res√≠duos e biomassa residual florestal permitiu a melhoria dos produtos de gasifica√ß√£o, constituindo desta forma uma estrat√©gia bastante promissora a n√≠vel econ√≥mico e ambiental, devido √† elevada abund√Ęncia e baixo custo dos res√≠duos urbanos. Contudo, devem ser efetuadas an√°lises t√©cnico-econ√≥micas e de ciclo de vida para a completa carateriza√ß√£o do processo. Em terceiro, a aplica√ß√£o de catalisadores de baixo custo como medida prim√°ria demonstrou elevado potencial para a melhoria do g√°s produto (e.g., concentra√ß√£o de H2 e CO, poder calor√≠fico inferior) e para o incremento dos par√Ęmetros de efici√™ncia do processo; em particular, a aplica√ß√£o de bet√£o, faialite sint√©tica e carbonizados de pellets de madeira, demonstrou resultados promissores. Finalmente, foi demonstrada a viabilidade econ√≥mica da integra√ß√£o do processo de gasifica√ß√£o direta (ar) de biomassa na ind√ļstria da pasta e papel, apesar dos par√Ęmetros determinados n√£o serem atrativos para potenciais investidores. Neste contexto, a interven√ß√£o dos governos e o desenvolvimento de instrumentos de apoio econ√≥mico √© de grande relev√Ęncia para a implementa√ß√£o destes projetos.Este trabalho foi financiado pela The Navigator Company e por Fundos Nacionais atrav√©s da Funda√ß√£o para a Ci√™ncia e a Tecnologia (FCT).Programa Doutoral em Engenharia da Refina√ß√£o, Petroqu√≠mica e Qu√≠mic

    Predictive Maintenance of Critical Equipment for Floating Liquefied Natural Gas Liquefaction Process

    Get PDF
    Predictive Maintenance of Critical Equipment for Liquefied Natural Gas Liquefaction Process Meeting global energy demand is a massive challenge, especially with the quest of more affinity towards sustainable and cleaner energy. Natural gas is viewed as a bridge fuel to a renewable energy. LNG as a processed form of natural gas is the fastest growing and cleanest form of fossil fuel. Recently, the unprecedented increased in LNG demand, pushes its exploration and processing into offshore as Floating LNG (FLNG). The offshore topsides gas processes and liquefaction has been identified as one of the great challenges of FLNG. Maintaining topside liquefaction process asset such as gas turbine is critical to profitability and reliability, availability of the process facilities. With the setbacks of widely used reactive and preventive time-based maintenances approaches, to meet the optimal reliability and availability requirements of oil and gas operators, this thesis presents a framework driven by AI-based learning approaches for predictive maintenance. The framework is aimed at leveraging the value of condition-based maintenance to minimises the failures and downtimes of critical FLNG equipment (Aeroderivative gas turbine). In this study, gas turbine thermodynamics were introduced, as well as some factors affecting gas turbine modelling. Some important considerations whilst modelling gas turbine system such as modelling objectives, modelling methods, as well as approaches in modelling gas turbines were investigated. These give basis and mathematical background to develop a gas turbine simulated model. The behaviour of simple cycle HDGT was simulated using thermodynamic laws and operational data based on Rowen model. Simulink model is created using experimental data based on Rowen’s model, which is aimed at exploring transient behaviour of an industrial gas turbine. The results show the capability of Simulink model in capture nonlinear dynamics of the gas turbine system, although constraint to be applied for further condition monitoring studies, due to lack of some suitable relevant correlated features required by the model. AI-based models were found to perform well in predicting gas turbines failures. These capabilities were investigated by this thesis and validated using an experimental data obtained from gas turbine engine facility. The dynamic behaviours gas turbines changes when exposed to different varieties of fuel. A diagnostics-based AI models were developed to diagnose different gas turbine engine’s failures associated with exposure to various types of fuels. The capabilities of Principal Component Analysis (PCA) technique have been harnessed to reduce the dimensionality of the dataset and extract good features for the diagnostics model development. Signal processing-based (time-domain, frequency domain, time-frequency domain) techniques have also been used as feature extraction tools, and significantly added more correlations to the dataset and influences the prediction results obtained. Signal processing played a vital role in extracting good features for the diagnostic models when compared PCA. The overall results obtained from both PCA, and signal processing-based models demonstrated the capabilities of neural network-based models in predicting gas turbine’s failures. Further, deep learning-based LSTM model have been developed, which extract features from the time series dataset directly, and hence does not require any feature extraction tool. The LSTM model achieved the highest performance and prediction accuracy, compared to both PCA-based and signal processing-based the models. In summary, it is concluded from this thesis that despite some challenges related to gas turbines Simulink Model for not being integrated fully for gas turbine condition monitoring studies, yet data-driven models have proven strong potentials and excellent performances on gas turbine’s CBM diagnostics. The models developed in this thesis can be used for design and manufacturing purposes on gas turbines applied to FLNG, especially on condition monitoring and fault detection of gas turbines. The result obtained would provide valuable understanding and helpful guidance for researchers and practitioners to implement robust predictive maintenance models that will enhance the reliability and availability of FLNG critical equipment.Petroleum Technology Development Funds (PTDF) Nigeri

    How to Use Haptic Technology in Interactive Digital Documentation of Heritage

    Get PDF
    Virtual restoration of the extinct heritage is a method of reconstruction of an already destroyed work in a virtual environment. It represents a way and an opportunity to reenter the remodeled simulated space interactively and experience its contemporary atmosphere and former author expression. In addition to visual and acoustic experiences, haptic technologies represent the potential for expanding sensory perception, which is not yet sufficiently used in the architectural sector. This study focuses on defunct and endangered works of interior architecture and industrial heritage, which were significant at the time of their inception and shaped the direction of the industry. Especially in the case of cultural and spiritual heritage, we focus on interiors, which, by their short-term nature, are neither objective nor physically documentable. Selected extinct works for which there was enough data or there was still the possibility of consultation with a living author were experimentally virtually reconstructed. Using haptic technologies, we have expanded the observer’s ability to interactively analyze space and its context through User Tracking of observers. The data obtained in this way continue to help the creators of the architecture set new starting points and limits for the current creation and design as well

    Comprehensive analysis of the combustion of low carbon fuels (hydrogen, methane and coke oven gas) in a spark ignition engine through CFD modeling

    Get PDF
    The use of low carbon fuels (LCFs) in internal combustion engines is a promising alternative to reduce pollution while achieving high performance through the conversion of the high energy content of the fuels into mechanical energy. However, optimizing the engine design requires deep knowledge of the complex phenomena involved in combustion that depend on the operating conditions and the fuel employed. In this work, computational fluid dynamics (CFD) simulation tools have been used to get insight into the performance of a Volkswagen Polo 1.4L port-fuel injection spark ignition engine that has been fueled with three different LCFs, coke oven gas (COG), a gaseous by-product of coke manufacture, H2 and CH4. The comparison is made in terms of power, pressure, temperature, heat release, flame growth speed, emissions and volumetric efficiency. Simulations in Ansys¬ģ Forte¬ģ were validated with experiments at the same operating conditions with optimal spark advance, wide open throttle, a wide range of engine speed (2000‚Äď5000 rpm) and air-fuel ratio (őĽ) between 1 and 2. A sensitivity analysis of spark timing has been added to assess its impact on combustion variables. COG, with intermediate flame growth speed, produced the greatest power values but with lower pressure and temperature values at őĽ = 1.5, reducing the emissions of NO and the wall heat transfer. The useful energy released with COG was up to 16.5% and 5.1% higher than CH4 and H2, respectively. At richer and leaner mixtures (őĽ = 1 and őĽ = 2), similar performances were obtained compared to CH4 and H2, combining advantages of both pure fuels and widening the őĽ operation range without abnormal combustion. Therefore, suitable management of the operating conditions maximizes the conversion of the waste stream fuel energy into useful energy while limiting emissions.This research was supported by the Project, ‚ÄúHYLANTIC‚ÄĚ- EAPA_204/2016, co-financed by the European Regional Development Fund within the framework of the Interreg Atlantic program and the Spanish Ministry of Science, Innovation and Universities (Project: RTI2018-093310-B-I00). Rafael Ortiz-Imedio thanks the Concepci√≥n Arenal postgraduate research grant from the University of Cantabria. The authors acknowledge Santander Supercomputaci√≥n support group at the University of Cantabria who provided access to the supercomputer Altamira Supercomputer at the Institute of Physics of Cantabria (IFCA-CSIC), member of the Spanish Supercomputing Network, for performing simulations. The authors also acknowledge the help provided for the model development by the Engineering Department from the Public University of Navarre in Pamplona
    • ‚Ķ
    corecore