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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Simulation and modelling of the performance of radial turbochargers under unsteady flow

Soler Blanco, Pablo 27 April 2020 (has links)
[ES] Está fuera de toda duda que la industria del automóvil está viviendo una profunda transformación que, durante los últimos años, ha progresado a un ritmo acelerado. Debido a la crecientemente estricta regulación sobre emisiones contaminantes y la necesidad de satisfacer la siempre creciente demanda de movilidad sostenible, es necesario que los motores de combustión modernos reduzcan su consumo y emisiones manteniendo el rendimiento del motor. Para enfrentarse a este desafío, los ingenieros de investigación y desarrollo han redoblado sus esfuerzos a la hora de diseñar y mejorar los modelos unidimensionales, hasta el punto en el que el desarrollo de modelos 1D así como la simulación juegan un papel fundamental en los primeras etapas de diseño de nuevos motores y tecnologías. Al mismo tiempo, la tecnología de turbosobrealimentación se ha consolidado como una de las más efectivas a la hora de construir motores de alta eficiencia, lo que ha hecho evidente la importancia de comprender y modelar correctamente los efectos asociados a los turbogrupos. Particularmente, los fenómenos que ocurren en la turbina en condiciones de flujo fuertemente pulsante han demostrado ser complicadas de modelar y sin embargo decisivas, ya que los códigos de simulación son especialmente útiles cuando son diseñados para trabajar en condiciones realistas. Este trabajo se centra en mejorar los modelos unidimensionales actuales así como en desarrollar nuevas soluciones con el objetivo de contribuir a una mejor predicción del comportamiento de la turbina sometida a condiciones de flujo pulsante. Tanto los esfuerzos realizados en los trabajos experimentales como en los de modelado se han producido para poder proporcionar métodos que sean fáciles de adaptar a las diferentes configuraciones de turbogrupo usadas en la industria, por ello, pueden ser aplicados por ejemplo en turbinas de entrada simple y también en las cada vez más usadas turbinas de entrada doble. En cuanto al trabajo de modelado en la parte de turbina de entrada simple, el foco se ha puesto en presentar una versión mejorada de un código quasi-2D. La validación del modelo se basa en los datos experimentales que están disponibles de trabajos enteriores de la literatura, proporcionando una comparación completa entre los modelos quasi-2D y el clásico modelo 1D. La presión a la entrada y salida de la turbina se ha descompuesto en ondas que viajan hacia delante y hacia atrás por medio de la descomposición de presiones, empleando la componente reflejada y transmitida para verificar la bondad del modelo. El trabajo experimental de esta tesis se centra en desarrollar un nuevo método para ensayar cualquier turbina de doble entrada sometida a condiciones de flujo fuertemente pulsante. La configuración del banco de gas se ha diseñado para ser suficientemente flexible como para realizar pulsos en las dos ramas de entrada por separado, así como para usar condiciones de flujo caliente o condiciones ambiente con mínimos cambios en la instalación. La campaña experimental se usa para validar un modelo integrado unidimensional de turbina tipo twin scroll con especial foco en las componentes reflejada y transmitida para analizar el desempeño del modelo su capacidad de predicción de la acústica no lineal. Finalmente, después de desarrollar el trabajo experimental y de modelado, se presenta un procedimiento para caracterizar el sonido y ruido de la turbina por medio de matrices de transferencia acústica que es comparado con el código unidimensional completo. En este sentido, el método proporciona una herramienta útil y fácil de implementar para simulaciones en tiempo real que aplica de una manera práctica el trabajo de modelado expuesto a lo largo de esta tesis. / [CAT] Està fora de tot dubte que la indústria de l'automòbil està vivint una profunda transformació que, durant els últims anys, ha progressat a un ritme accelerat. A causa de la creixentment estricta regulació sobre emissions contaminants i la necessitat de satisfer la sempre creixent demanda de mobilitat sostenible, és necessari que els motors de combustió moderns reduïsquen el seu consum i emissions mantenint el rendiment del motor. Per a enfrontar-se a aquest desafiament, els enginyers de recerca i desenvolupament han redoblat els seus esforços a l'hora de dissenyar i millorar els models unidimensionals, fins al punt en el qual el desenvolupament de models 1D així com la simulació juguen un paper fonamental en les primeres etapes de disseny de nous motors i tecnologies. Al mateix temps, la tecnologia de turbosobrealimentación s'ha consolidat com una de les més efectives a l'hora de construir motors d'alta eficiència, la qual cosa ha fet evident la importància de comprendre i modelar correctament els efectes associats als turbogrupos. Particularment, els fenòmens que ocorren en la turbina en condicions de flux fortament polsant han demostrat ser complicades de modelar i no obstant això decisives, ja que els codis de simulació són especialment útils quan són dissenyats per a treballar en condicions realistes. Aquest treball se centra en millorar els models unidimensionals actuals així com a desenvolupar noves solucions amb l'objectiu de contribuir a una millor predicció del comportament de la turbina sotmesa a condicions de flux polsant. Tant els esforços realitzats en els treballs experimentals com en els de modelatge s'han produït per a poder proporcionar mètodes que siguen fàcils d'adaptar a les diferents configuracions de turbogrupo usades en l'indústria, per això, poden ser aplicats per exemple en turbines d'entrada simple i també en les cada vegada més usades turbines d'entrada doble. Pel que fa al treball de modelatge en la part de turbina d'entrada simple, el focus s'ha posat a presentar una versió millorada d'un codi quasi-2D. La validació del model es basa en les dades experimentals que estan disponibles de treballs anteriors de la literatura, proporcionant una comparació completa entre els models quasi-2D i el clàssic model 1D. La pressió a l'entrada i eixida de la turbina s'ha descompost en ones que viatgen cap avant i cap enrere per mitjà de la descomposició de pressions, emprant la component reflectida i transmesa per a verificar la bondat del model. El treball experimental d'aquesta tesi se centra en desenvolupar un nou mètode per a assajar qualsevol turbina de doble entrada sotmesa a condicions de flux fortament pulsante. La configuració del banc de gas s'ha dissenyat per a ser prou flexible com per a realitzar polsos en les dues branques d'entrada per separat, així com per a usar condicions de flux calent o condicions ambient amb mínims canvis en la instal·lació. La campanya experimental s'usa per a validar un model integrat unidimensional de turbina tipus twin-scroll amb especial focus en les components reflectida i transmesa per a analitzar l'acompliment del model la seua capacitat de predicció de l'acústica no lineal. Finalment, després de desenvolupar el treball experimental i de modelatge, es presenta un procediment per a caracteritzar el so i soroll de la turbina per mitjà de matrius de transferència acústica que és comparat amb el codi unidimensional complet. En aquest sentit, el mètode proporciona una eina útil i fàcil d'implementar per a simulacions en temps real que aplica d'una manera pràctica el treball de modelatge exposat al llarg d'aquesta tesi. / [EN] It is beyond all doubt that the automotive industry is living a deep transformation that, during the last years, has progressed at an ever accelerating rate. Due to the increasingly stringent pollutant emission regulations and the necessity to fulfil an ever growing demand for sustainable mobility, the modern internal combustion engines are required to strongly reduce the fuel consumption and emissions, while keeping the engine performance. In order to confront this challenge, engine research and development engineers have redoubled their efforts in designing and improving one-dimensional codes, to the point that the development of 1D models and simulation campaigns play a major role in the early steps of designing new engines or technologies. At the same time as the turbocharging technology has arisen as one of the most effective and extended solutions for building high efficient engines, the importance of understanding and modelling correctly the turbocharger effects has become evident. In particular, the phenomena that occurs in the turbine under highly pulsating conditions have proven to be challenging to model and yet decisive, as simulation codes are especially useful when they are designed to work under realistic conditions. This work focusses on the improvement of current one-dimensional models as well as in the development of new solutions with the aim of contributing to a better prediction of the turbine performance under pulsating conditions. Both experimental and modelling efforts have been made in order to provide methods that are easily adaptable to different turbocharger configurations used in the industry, so they can be applied for example in single turbines and also in the increasingly used two-scroll turbine technology. Regarding the modelling work of the single entry turbine part, the work has been focused in presenting an improved version of a quasi-2D code. The validation of the model is based on the experimental data available from previous works of the literature, providing a complete comparison between the quasi-2D and a classic 1D model. By means of a pressure decomposition, the pressure at the turbine inlet and outlet has been split into forward and backward travelling waves, employing the reflected and transmitted components to verify the goodness of the model. The experimental work of the thesis is centred in developing a new method in order to test any two-scroll turbine under highly pulsating flow conditions. The gas stand setup has been designed to be flexible enough to perform pulses in both inlet branches separately as well as to use hot or ambient conditions with minimal changes in the installation. The experimental campaign is used to fully validate an integrated 1D twin-scroll turbine model with special focus in the reflected and transmitted components for analysing the performance of the model and its non-linear acoustics prediction capabilities. Finally, after the experiment and modelling work is developed, a procedure to characterise the turbine sound and noise by means of acoustic transfer matrices is presented and tested against the fully one-dimensional code. In this sense, this method provides a useful and easily-implementable tool for fast and real time simulations that applies in a practical way the modelling work exposed along this thesis. / Soler Blanco, P. (2020). Simulation and modelling of the performance of radial turbochargers under unsteady flow [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/141609 / TESIS
52

Jednoválcový motor pro silniční motocykl / Single-cylinder Engine of a Road Motorcycle

Čech, Martin January 2016 (has links)
This thesis is focusing on the construction of a four-stroke internal combustion engine for a 250 ccm road bike. Since it is a road bike, the introduction of legislation of the Czech Republic for this category is outlined in the introduction of the thesis. Furthermore, disassembling of similar and competitive engine was conducted. The thesis also describes the process of construction of this four-stroke internal combustion engine. In addition, the thesis compares friction loss on the main bearing crankshaft. In the latter part there is summarization of all findings.
53

Injector diagnosis based on engine angular velocity pulse pattern recognition

Nyman, David January 2020 (has links)
In a modern diesel engine, a fuel injector is a vital component. The injectors control the fuel dosing into the combustion chambers. The accuracy in the fuel dosing is very important as inaccuracies have negative effects on engine out emissions and the controllability. Because of this, a diagnosis that can classify the conditions of the injectors with good accuracy is highly desired. A signal that contains information about the injectors condition, is the engine angular velocity. In this thesis, the classification performance of six common machine learning methods is evaluated. The input to the methods is the engine angular velocity. In addition to the classification performance, also the computational cost of the methods, in a deployed state, is analysed. The methods are evaluated on data from a Scania truck that has been run just like any similar commercial vehicle. The six methods evaluated are: logistic regression, kernel logistic regression, linear discriminant analysis, quadratic discriminant analysis, fully connected neural networks and, convolutional neural networks. The results show that the neural networks achieve the best classification performance. Furthermore, the neural networks also achieve the best classification performance from a, in a deployed state, computational cost effectiveness perspective. Results also indicate that the neural networks can avoid false alarms and maintain high sensitivity.
54

Biomass and Natural Gas Hybrid Combined Cycles

Petrov, Miroslav January 2003 (has links)
Biomass is one of the main natural resources in Sweden.Increased utilisation of biomass for energy purposes incombined heat and power (CHP) plants can help the country meetits nuclear phase-out commitment. The present low-CO2 emissioncharacteristics of the Swedish electricity production system(governed by hydropower and nuclear power) can be retained onlyby expansion of biofuels in the CHP sector. Domestic Swedishbiomass resources are vast and renewable, but not infinite.They should be utilised as efficiently as possible in order tomeet the conditions for sustainability in the future.Application of efficient power generation cycles at low cost isessential for meeting this challenge. This applies also tomunicipal solid waste (MSW) incineration with energyextraction, which is to be preferred to landfilling. Modern gas turbines and internal combustion engines firedwith natural gas have comparatively low installation costs,good efficiency characteristics and show reliable performancein power applications. Environmental and source-of-supplyfactors place natural gas at a disadvantage as compared tobiofuels. However, from a rational perspective, the use ofnatural gas (being the least polluting fossil fuel) togetherwith biofuels contributes to a diverse and more secure resourcemix. The question then arises if both these fuels can beutilised more efficiently if they are employed at the samelocation, in one combined cycle unit. The work presented herein concentrates on the hybriddual-fuel combined cycle concept in cold-condensing and CHPmode, with a biofuel-fired bottoming steam cycle and naturalgas fired topping gas turbine or engine. Higher electricalefficiency attributable to both fuels is sought, while keepingthe impact on environment at a low level and incorporating onlyproven technology with standard components. The study attemptsto perform a generalized and systematic evaluation of thethermodynamic advantages of various hybrid configurations withthe help of computer simulations, comparing the efficiencyresults to clearly defined reference values. Results show that the electrical efficiency of hybridconfigurations rises with up to 3-5 %-points in cold-condensingmode (up to 3 %-points in CHP mode), compared to the sum of twosingle-fuel reference units at the relevant scales, dependingon type of arrangement and type of bottoming fuel. Electricalefficiency of utilisation of the bottoming fuel (biomass orMSW) within the overall hybrid configuration can increase withup to 8-10 %-points, if all benefits from the thermalintegration are assigned to the bottoming cycle and effects ofscale on the reference electrical efficiency are accounted for.All fully-fired (windbox) configurations show advantages of upto 4 %-points in total efficiency in CHP mode with districtheating output, when flue gas condensation is applied. Theadvantages of parallel-powered configurations in terms of totalefficiency in CHP mode are only marginal. Emissions offossil-based CO2 can be reduced with 20 to 40 kg CO2/MWhel incold-condensing mode and with 5-8 kg CO2 per MWh total outputin CHP mode at the optimum performance points. Keywords: Biomass, Municipal Solid Waste (MSW), Natural Gas,Simulation, Hybrid, Combined Cycle, Gas Turbine, InternalCombustion Engine, Utilization, Electrical Efficiency, TotalEfficiency, CHP. / NR 20140805
55

BYU Diesel Engine Lab Setup and Parasitic Losses of the Water Pump and Vacuum Pump on a Cummins 2.8L Engine

Jessup, Eric Ashton 05 June 2020 (has links)
The need to minimize carbon dioxide (CO2) emissions is becoming increasingly important with the total number of vehicles throughout the world exceeding one billion. Carbon dioxide emissions can be reduced by improving vehicle fuel efficiency. While electric transportation is gaining popularity, most passenger vehicles are still powered by gasoline or diesel engines. The main objective of this work was to provide opportunities for studying and improving the fuel efficiency of internal combustion engines (ICE). This was achieved by 1) Designing, building and testing auxiliary systems necessary to run a Cummins 2.8 L engine in a an engine test cell; 2) Creating educational labs for the ICE class; and 3) Measuring the parasitic losses of the vacuum pump and water pump on the installed Cummins 2.8 L diesel engine. All auxiliary systems were completed at a hardware cost of $8100 and are rated to support an engine with the power output capacity of 233 kW (312 hp). The educational laboratories enable future engineers to measure and assess the efficiency of internal combustions engines. The parasitic losses of the vacuum pump and water pump were found to impact the relative brake fuel conversion efficiency by 1.3% and 1.5% respectively over the Federal Test Procedure (FTP) cycle.
56

A Deep Reinforcement Learning Framework for Optimizing Fuel Economy of Vehicles

Toor, Omar Zia January 2022 (has links)
Machine learning (ML) has experienced immense growth in the last decade; applications of ML are found in nearly every sphere of society. We gather a vast amount of data during our day-to-day operations, and the machines use this data to make intelligent decisions for us. Transport is an essential part of our life. Since early times it has been a critical requirement of human beings, and as we progressed, its need has risen tremendously. Nowadays, we cannot think of a life without any means of transportation. A vehicle is the primary means of transportation in the modern industrial world. Most of the world's population uses a vehicle for transportation needs. The internal combustion engine (ICE) has been the vehicle's primary power source since the early days. Approximately 99% of world transport uses internal combustion engine-based vehicles. As with every other device, Internal combustion technology has seen enormous improvement during the past half a century. These gradual improvements have made these ICEs better than ever before. But as we have progressed, we have also been exposed to the harms of combustion-based power sources like ICEs. Their effect on the environment has been damaging. The future way is to limit the use of hydrocarbon-based fuels for combustion. As it's nearly impossible to eradicate the use of these fuels instantly as most of the population is deeply dependent on them, the best way to proceed is to find alternate transportation sources like EVs. But as these technologies are developing, it's of great importance; we use our modern ML-based technologies to make the current ICE-based vehicles as fuel-efficient as possible so that this transition to electric-based vehicles becomes smooth and the effect of ICEs is minimized on the environment. The thesis presents a deep reinforcement learning (DRL) based technique, which can develop an optimal policy to effectively reduce vehicle fuel consumption by providing intelligent driving inputs to the vehicle. The study shows that it is possible to use (DRL) methods to improve fuel efficiency in a simulated vehicular environment. Moreover, the models seem to develop new types of operational vehicle policies that are very unconventional but result in improved fuel efficiency in simulated environments. Although these cannot be implemented in the current form in the actual environment, modified versions of these policies may be able to work in real-life scenarios.
57

Model-Order Reduction for Nonlinear Distributed Parameter Systems with Application to Internal Combustion Engine Modeling and Simulation

Stockar, Stephanie 30 August 2013 (has links)
No description available.
58

Accuracy verification of GT-Power model and reduction of computational time / Noggrannhetsverifiering av modell i GT-Power och reducering av beräkningstid

Dahl, Viktor, Dyrsmeds, Maja January 2022 (has links)
The noise produced by any new vehicles is tightly regulated by the European Union which have developed a standardised method for measuring the emitted noise of new vehicles. The method involves a vehicle driving past carefully positioned microphones at a specific range of engine speeds. Doing actual tests is time consuming and cost inefficient, thus, it would be beneficial to minimise the number of tests performed during development. There are multiple different noise sources contributing to the total noise levels emitted by a truck such as, aerodynamic noise, road noise, exhaust noise etc. In this project solely the exhaust noise will be investigated. There are existing models that can simulate the exhaust noise by using the source characteristics of the engine. The accuracy of the models that can calculate the source data is uncertain and they are often computationally heavy. Therefore, the purpose of this project is to verify the accuracy of the source acoustics of the engine for one such model and try to minimise the calculation times. To verify the accuracy of existing models a test is constructed that will be performed both by measurements and simulations in GT-Power. The aim is to use both methods to predict the source pressure and impedance, then compare the results and analyse any similarities. The test setup works as the guide for how to design the simulation model. This is mainly due to the difficulty to procure the necessary equipment needed to perform the test. Thus, the simulation models had to be adapted to match the layout of the test to the extent it is possible. The data obtained through testing needs to be post processed by performing an averaging to reduce the noise and use the two microphone method to calculate the source pressure. The data from simulation is also processed through a Multi-Load method to estimate the source pressure. The sound pressure level is then cal- culated for each method and the total SPL for each method is compared over the entire rev range. However, the resulting total SPL from each of the two approaches are different to each other. This suggests that the simulations should be used with caution when analysing acoustics. To try and reduce the computational time, one method is to reduce the size of the input data. This can be done in two different ways, either by reducing the number of engine speeds investigated or by reducing the number of frequencies analysed for each engine speed. Reducing speeds might not always be possible, thus, reducing the number of frequencies for each speed will be investigated. Analysing the pressure signal in the frequency domain show that the frequencies linked to the engine orders contain significantly larger pressures than the rest of the frequencies. Thus, solely these frequencies could be used to reduce the computational time but still give a representative result. In order to analyse the affect of removing frequencies the total acoustic energy is calculated for each engine speed and is compared with the acoustic energy of the frequencies belonging to the five first engine orders for the same speeds. These calculations of the sound energy show that the five first engine orders contain above 95% of the total sound energy for each engine speed. This suggests that it might be viable to use solely the pressure produced by the engine orders and still produce representative simulations. Thus, reduce the calculation time without affecting the results substantially. / Det bullernivåer som nyproducerade fordon avger är något som är strikt reglerat av Europeiska unionen som har tagit fram en standardiserad metod för att mäta det buller som avges från nya fordon. Metoden innefattar att ett fordon kör förbi ett antal noga utplacerade mikrofoner under en specifik del av varvtalsområdet. Att utföra dessa tester är både tidkrävande och kostsamt. Därför skulle det vara förmånligt att minimera antalet tester som behöver utföras under utvecklingsprocessen. Det är flera olika ljudkällor som bidrar till det totala ljudet som avges från ett fordon, bland annat, vindljud, vägljud och avgasljud. I detta projekt kommer endast avgasljudet analyseras. Det finns modeller som kan simulera avgasljudet genom att beräkna källdata från motorn. Noggrannheten hos dessa tester är dock fortfarande en osäkerhet och de är ofta beräkningstunga. Syftet med detta projekt är att undersöka noggrannheten hos dessa modeller samt att försöka minska tiden simuleringarna tar utan att påverka resultatet märkbart. För att undersöka noggrannheten kommer ett fysiskt test att utföras som sedan kommer att imiteras i GT-Power. Målet är att använda båda metoderna för att beräkna källtryck samt källimpedans för att sedan jämföra dessa resultat och analysera eventuella likheter. Testets utformning får agera som riktmärke för hur modellerna ska utformas. Detta är främst på grund av begränsade valmöjligheter när det kommer till de komponenter som behövs för att utföra testet. Därför är det smidigast att anpassa modellerna efter de komponenter som finns att tillgå för testet i den utsträckning det är möjligt. Den rådata som insamlas under testets gång behöver efterbehandlas genom att utföra en medelvärdesbildning för att minska bruset på signalerna. Samt att två mikrofonsmetoden behöver användas för att beräkna källtrycket. Data från simuleringarna behöver också behandlas för att beräkna källtrycket, men genom Multi-Load metoden. För båda metoderna beräknas sedan den totala ljudtrycksnivån för varje utvalt varvtal. Dessa ljudtrycksnivåer jämförs sedan med varandra över hela varvtalsområdet. Dock finns det en väsentlig skillnad mellan dessa två resultat. Detta tyder på att simuleringarna skall användas med försiktighet när det gäller akustiska analyser. För att minimera modellernas beräkningstid kan en metod vara att reducera mängden indata som använda. Detta kan göras på två olika sätt, antingen minskas antalet varvtal som tas i beaktning eller så minskas antalet frekvenser som ingår i varje varvtal. Att minska antalet undersökta varvtal är inte alltid ett alternativ, därför passar det bättre att undersöka möjligheten att minska antalet frekvenser som ingår i varje varvtal. När trycksignalerna för varje varvtal analyseras i frekvensplanet visar det sig att de frekvenser som är knutna till motorordningarna innehåller betydligt högre tryck än de resterande. Därför borde beräkningar men endast frekvenser knutna till motorordningarna kunna reducera beräkningstiden och fortfarande bibehålla ett representativt resultat. För att analysera påverkan av att reducera antalet frekvenser beräknas den totala akustiska energin för varje varvtal med samtliga frekvenser och denna jämförs med energin beräknad med endast trycken från de fem första motorordningarna inkluderade. Dessa energiberäkningar visar att den akustiska energi som finns i de fem första motorordningarna motsvarar mer än 95% av den totala akustiska energin i signalen. Detta tyder på att det är möjligt att endast ta dessa frekvenser i beaktning och ändå bibehålla en representativ simulering. Således minska beräkningstiden utan att påverka resultatet väsentligt.
59

Fuel spray modeling for application in internal combustion engines /

Ribeiro, Mateus Dias January 2019 (has links)
Orientador: José Antônio Perrella Balestieri / Abstract: Direct injection spark ignition (DISI) engines aim at reducing specific fuel consumption and achieving the strict emission standards in state of the art internal combustion engines. Therefore, in this work the goal is to develop code for simulations of the internal flow in DISI engines, as well as the phenomenon of fuel spray injection into the combustion chamber using a Lagrangian-Eulerian approach for representing the multiphase flow, and Large-eddy Simulations (LES) for modeling the turbulence of the continuum medium by means of the open-source CFD library OpenFOAM. In order to validate the obtained results and the developed models, experimental data from the Darmstadt optical engine, and the non-reactive “Spray G” gasoline injection case, along with the reactive “Spray A” case from the Engine Combustion Network (ECN) will be employed. Finally, a novel open-source solver will be proposed to simulate the Darmstadt optical engine in motored and fired operation under stratified mixture condition, using data compiled by the Darmstadt Engine Workshop (DEW) for validation. Moreover, a deep learning framework is presented to train an artificial neural network (ANN) with the engine LES data generated in this work, in order to make predictions of the small scale turbulence behavior. / Resumo: Motores de ignição a centelha com injeção direta (direct injection spark ignition engines, DISI engines) visam reduzir o consumo específico de combustível e respeitar os restritos níveis de emissão em motores de combustão interna de última geração. Assim, pretende-se com este trabalho desenvolver código para simulação do escoamento interno em motores DISI, assim como os fenômenos de injeção de combustível no interior da câmara de combustão utilizando uma abordagem Lagrangeana-Euleriana para representação do escoamento multifásico e Simulação de Grandes Escalas (Large-eddy simulation, LES) para a modelagem da turbulência no meio contínuo, por intermédio da biblioteca CFD de código aberto OpenFOAM. De modo a validar os resultados e os modelos desenvolvidos, dados experimentais serão utilizados, obtidos do motor óptico de Darmstadt, e do caso de teste de injeção de gasolina não-reativo “Spray G”, juntamente com o caso reativo “Spray A” da Rede de Combustão em Motores (Engine Combustion Network, ECN). Enfim, um novo código aberto será proposto para simular o motor óptico de Darmstadt em condições de escoamento a frio (sem combustão) e com combustão em condição de mistura estratificada, usando dados compilados pelo Workshop do Motor de Darmstadt (Darmstadt Engine Workshop, DEW) para validação. Além disso, uma abordagem de aprendizado profundo (deep learning) será apresentada para treinar uma rede neural artificial (artificial neural network, ANN) com dados de simulação LES de moto... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor
60

Aplicação de tecnologias de cogeração na produção conjunta de biodiesel e biohidrogênio /

Cantagallo, João Paulo Tavares January 2019 (has links)
Orientador: Pedro Magalhães Sobrinho / Resumo: O Brasil tem uma grande capacidade para produzir biocombustíveis devido a sua extensa área territorial com grande produtividade de matéria-prima para este setor. O Governo Federal vem investindo bastante neste setor, pois além de ser estratégico economicamente, também tem grandes vantagens na luta contra o aquecimento global. Desde 2005, ano em que se iniciou a comercialização do biodiesel em caráter voluntário, até 2017 a produção cresceu de 736 m3/ano para 4291294 m3/ano. Isto se deu devido a política de aumento obrigatório da porcentagem de biodiesel misturado ao diesel de petróleo de forma gradativa até o nível de 10% (B10) em 2018. Neste trabalho propõe-se um sistema de cogeração utilizando um motor de combustão interna (queimando gás natural), um queimador suplementar e uma caldeira de recuperação para gerar energia elétrica e vapor superaquecido necessário para o processo de reforma a vapor do glicerol; comparando-o com outro sistema proposto por Galarza (2017) que utiliza microturbina à gás. Este sistema será estudado para uma planta capaz de produzir 17820 m3/ano de biodiesel operando 7920 h/ano. Foi escolhido um motor de combustão interna com potência de 200 kW e consumo de 42,9 kg/h, pois foi o motor com menor consumo, mas que mantêm o nível de temperatura dos gases de exaustão (471,8 ºC). Energeticamente o sistema se demonstrou viável, mas possui grande perda de calor na chaminé que poderia ser aproveitada, como na produção de água quente por exemplo. A análise ex... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Brazil has a large capacity to produce biofuels due to its extensive land area with high productivity of raw material for this sector. The Federal Government has been investing a lot in this sector, since besides being economically strategic, it also has great advantages in the fight against global warming. Since 2005, when the commercialization of biodiesel began on a voluntary basis, by 2017 production increased from 736 m3/year to 4291294 m3/year. This was due to the policy of mandatory increase of the percentage of biodiesel mixed with petroleum diesel gradually until the level of 10% (B10) in 2018. In this work, a cogeneration system is proposed using an internal combustion engine (burning natural gas), an additional burner and a recovery boiler to generate electrical energy and superheated steam necessary for the steam reforming process of glycerol; comparing it with another system proposed by Galarza (2017) that uses microturbine to gas. This system will be studied for a plant capable of producing 17820 m3/year of biodiesel operating at 7920 hours per year. An internal combustion engine with a power of 200 kW and a consumption of 42.9 kg/h was chosen, because it was the engine with the lowest consumption, but it maintains the level of temperature of exit (471.8 ºC). Energetically the system has proven viable, but it has great heat loss in the chimney that could be better used, as in the production of hot water for example. Exergetic analysis helps to understand the sys... (Complete abstract click electronic access below) / Mestre

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