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Given the importance of diagnosing internal combustion engines and their expandingmarket, it is crucial to investigate the complex dynamics of these engines and developa model to detect and localize component and sensor faults, independent of operatingconditions. This master’s thesis explores capturing dynamic relationships in engine signalsto detect faults. Internal combustion engines have highly nonlinear dynamics that arenot easy to capture with basic system identification methods. Consequently, some newlydeveloped methods, such as Sparse Identification of Nonlinear Dynamics (SINDy) andAuto Regressive (AR) models, have been implemented to address the governing equations.Following previous research in this field, some analytical relations between the sensorswere known. Additionally, these equations provide the sensitivity of residuals based onthe input sensor fault. By implementing the mentioned methods and using informationfrom the analytical equations, some relationships between the sensor values and the inputfault have been identified.After finding these dynamic relationships between the sensor values, a classificationalgorithm was selected to classify the sensor faults. Additionally, to estimate the faultseverities (sensor inaccuracies), some regression models have been implemented. Further-more, it was desired to evaluate the isolability of the faults, and in this regard, some newconstraints have been considered to reconstruct the relations with the desired isolability.Finally, through several evaluations, it was shown that the proposed method is not af-fected by the driving cycle. However, this research established these methods based on aspecific case study, which is a specific turbocharged internal combustion engine.

For diesel engines, valve timing is important and is related to power efficiency and exhaust gas after-treatment. During operation, the temperature of engine components can change and thus influencing the actual valve timing. With collected data from a Scania experimental engine, a method for valve closing time detection based on knock sensors is proposed in this project using a signal processing method. For algorithm design and result evaluation purposes, two references are used in this project. One is nominal valve timing, and the other is a valve timing reference based on rocker arm force signals. The developed method is tested through 4 evaluations: (1) 30% engine load with different engine speeds (600 to 2000rpm), (2) 1200rpm engine speed with different engine loads (0 to 100%), (3) 40% load 1200rpm at different oil temperature (around 50 to 80°C), and (4) 40% load dropped to motored condition. By comparing evaluation results and previously reported data, the following conclusions can be drawn: (a) The developed method has the ability to catch the changing of valve closing time in most test cases; (b) The developed method has a maximum combined error (between detected valve closing and rocker arm unloaded time) of - 4.7CAD on the intake side and -12.6CAD on the exhaust side among all cylinders; (c) Due to interference from vibration caused by valve events of other cylinders, the developed method has worse accuracy with larger than 50% load. Further work can focus on the detection of valve opening time and the improvement of accuracy by finding better sensor positions. / För dieselmotorer är ventiltidpunkten viktig och relaterad till energieffektivitet och avgasefterbehandling. Under drift kan temperaturen på motorkomponenterna förändras och därmed påverka ventilernas faktiska timing. Med insamlade data från en Scania experimentell motor föreslås i detta projekt en metod för detektering av ventilstängningstid baserad på knackgivare med hjälp av en signalbehandlingsmetod. För algoritmdesign och resultatutvärdering används två referenser i detta projekt. Den ena är nominell ventiltidpunkt och den andra är en ventiltidsreferens baserad på vipparmskraftssignaler. Den utvecklade metoden testas genom 4 utvärderingar: (1) 30% motorbelastning med olika motorvarvtal (600 till 2000r/min), (2) 1200r/min motorvarvtal vid olika motorbelastningar (0 till 100%), (3) 40% belastning 1200r/min vid olika oljetemperatur (runt 50 till 80 °C), och (4) 40% belastning till motordrivet tillstånd. Genom att jämföra utvärderingsresultat och tidigare rapporterade data kan följande slutsatser dras: (a) Den utvecklade metoden har förmågan att fånga ändring av ventilstängningstiden i de flesta testfall; (b) Den utvecklade metoden har ett maximalt kombinerat fel (mellan detekterad ventilstängning och vipparmslasttid) på -4,7CAD på inloppssidan och -12,6CAD på avgassidan bland alla cylindrar. (c) På grund av vibrationsstörningar orsakade av ventilhändelser hos andra cylindrar har den utvecklade metoden sämre noggrannhet med större än 50% last. Det fortsatta arbetet kan fokusera på detektering av ventilernas öppningstid, förbättring av noggrannheten genom att hitta bättre givarpositioner.

Controlling the temperature of the exhaust valves is paramount for proper functioning of engines and for the long lifespan of valve train components. The majority of the heat outflow from the valve takes place along the valve-seat-cylinder head-coolant thermal path which is significantly influenced by the thermal contact resistance (TCR) present at the valve/seat and seat/head interfaces. A test rig facility and experimental procedure were successfully developed to assess the effect of the valve/seat and seat/head interfaces on heat outflow from the valve, in particular the effects of the valve/seat interface geometry, seat insert assembly method, i.e. press or shrink fit, and seat insert metallic coating on the operating temperature of the valve. The results of tests have shown that the degree of the valve-seat geometric conformity is more significant than the thermal conductivity of the insert: for low conforming assemblies, the mean valve head temperature recorded during tests on copper-infiltrated insert seats was higher than that recorded during tests on noninfiltrated seats of higher conformance. The effect of the insert-cylinder head assembly method, i.e. shrink-fitted versus press-fitted inserts, has proved negligible: results have shown insignificant valve head temperature variations, for both tin-coated and uncoated inserts. On the other hand, coating the seat inserts with a layer of tin (20-22μm) reduced the mean valve head temperature by approximately 15°C as measured during tests on uncoated seats. The analysis of the valve/seat and seat/head interfaces has indicated that the surface asperities of the softer metal in contact would undergo plastic deformation. Suitable thermal contact conductance (TCC) models, available in the public domain, were used to evaluate the conductance for the valve/seat and seat/cylinder head interfaces. Finally, a FE thermal model of the test rig has been developed with a view to assess the quality of the calculated TCC values for the valve/seat and seat/head interfaces. The results of the thermal analysis have shown that predicted temperatures at chosen control points agree with those measured during tests on thermometric seats with an acceptable level of accuracy, proving the effectiveness of the used TCC models.

A modelagem de motores a combustão interna deve grande parte de sua importância ao uso de unidades de controle eletrônicas que buscam gerenciar as funções do motor. De forma a fornecer melhor suporte para o projetista de controle, a modelagem oferece informações que servem de planta, sobre a qual estratégias de controle serão desenvolvidas. Nesta dissertação, procurou-se estudar e modelar cinco fenômenos: a admissão de ar e de combustível, a produção de energia efetiva através da combustão, a evolução térmica do motor e o comportamento dos gases no sistema de exaustão. Investigou-se também, em todos estes fenômenos, a influência do uso de composição variada gasolina/etanol. Na admissão de ar, buscou-se estudar como a abertura da válvula borboleta e a velocidade do motor influenciam no fluxo de ar admitido, ponderando esta grandeza através de um fator de correção denominado eficiência volumétrica. Na admissão de combustível, no caso modelada para motores com injeção indireta na porta, procurou-se explanar quantitativamente sobre os diversos aspectos que influenciam a evaporação do combustível. Na geração de energia útil, priorizou-se a análise de como as características do motor e da combustão afetam a produção de torque. Na evolução térmica do motor, examinaram-se os principais fluxos energéticos do motor e os aspectos que os influenciam. Ademais, foram executadas as validações dos modelos levantados para o motor EA 111 VHT 1.6l. Os resultados, com seus respectivos erros, podem ser encontrados neste trabalho. / The internal combustion engine modeling owes big part of its importance to the use of electronic control units that aim to manage the engine functions. To provide better support to the control designer, the modeling offers information that can compose the plant, on which control strategies will be developed. In this master thesis, it was sought to study and to model five phenomena: the air intake and the fuel admission, the effective energy production from the combustion, the engine thermic evolution and the gas behavior in the exhaust system. It was also considered how the influence of the gasoline/ethanol varied composition affects all these phenomena. In the air intake, it was studied how the butterfly valve opening and the engine speed influence the intake air flow, pondering this variable through a correction factor named volumetric efficiency. In the fuel admission, in the case of this study modelled for port-fuel injection engines, it was attempted to explain quantitatively the many aspects that influence the fuel evaporation. In the mechanical energy generation, it was prioritized the analysis about how the engine and combustion characteristics affect the torque production. In the engine thermic evolution, it was examined the major energy flows and the aspects that influence them. Also, the validations of the models raised for the EA 111 VHT 1.6l engine were executed. The results, with its respective errors, can be found in this work.

O trabalho consiste em análises experimental, teórica e computacional do escoamento dos gases de exaustão através de um conversor catalítico platina-paládio, instalado num motor de combustão interna movido a etanol. Foram realizados ensaios dinanométricos no motor para análise das medidas experimentais no sistema de exaustão e para aquisição de valores das propriedades termodinâmicas, de transporte e de concentrações químicas, os quais serviram de dados iniciais para a simulação computacional desenvolvida com a utilização dos softwares CFX e MFIX. Os programas resolvem um conjunto de equações conservativas que permitem a análise da variação da pressão, temperatura, velocidade e composição química dos gases de escape ao longo do suporte monolítico. Além de avaliar a formação e os níveis das emissões provenientes da combustão da mistura ar-combustível. A eficiência catalítica no primeiro suporte do conversor foi de 11% THC, 100% NOx e 20% CO. Foi verificada uma diferença de 1,23% entre a velocidade média experimental e a simulada. Modelos matemáticos foram aplicados no estudo da perda de carga no conversor catalítico e na relação difusão-reação do consumo e formação das espécies químicas. / The thesis describes computational, experimental, and theoretical analysis of the exhaust gases flow through a Pt/Pd catalytic converter installed on internal combustion engine burning ethanol. The obtained values related to energy properties and mass transport in experimental tests is the base of initial values for development of the computational simulation by using CFX and MFIX software. The programs solves a group of conservative equations that allow to analysis of variation such as pressure, temperature, and also, velocity of exhausting gases along the monolithic support, moreover to evaluate the formation of gases and its emission levels on the incoming air-fuel mixture combustion and its respective chemical reactions of oxidation. The catalytic efficiency through the first monolith of the converter were about of 11% THC, 100% NOx e 20% CO. It was verified also a small difference of 1,2 % between the experimental and the simulated average velocity. In addition mathematical models were applied on the study of the load loss in catalytic converter, diffusion-reaction of the consumption and also formation of chemical species.

Power generation from biomass based renewable energy technologies is a promising option in retrofitting our dependence in conventional power generation processes. The development of any society is not possible without sustainable energy and access to energy creates that environment that allows the world to thrive. Electricity access especially in developing regions of the world is of particular interest. This work provides results on electricity efficiency, the economic feasibility and environmental impact of biomass based power technologies in small scale setting using Aspen Plus software. The power generation processes analysed on standalone basis include - micro gas turbine, gas turbine, steam turbine, Stirling engine and internal combustion engine. Some of the processes are optimized in the design to suit the specific climate and available wood waste stream in Nigeria is considered in this work. Simulation results indicate that gas engines power technologies gave a better electric performance of more than 30% with its integration with biomass gasification technology in production of fuel gas. The stirling engine power technology shows a good prospect despite its yet to be commercial status. The modification of the engine (removal regenerator) gives a better electric efficiency. Also result shows that internal combustion engine process emits more of nitric oxides compared to other technologies which create doubts over its environmental compatibility. Economic studies show that for small scale power generation, internal combustion engines and stirling engines are economic feasible. Also, steam turbine and gas turbine illustrate why they are mostly applied in medium/large scale biomass power generation specially recommended to regions where more biomass resource are produced. The micro gas turbine power technology can also be applied in small scale despite its high total investment capital. Furthermore, the study shows that about from 1.8 million tonnes per year of saw dust (wood waste) produced from lumber industries in Nigeria, about 1.3 TWh of electricity can be generated from 1000 MW power plant. Power generation via the utilization of biomass prove to be a possible path to Nigeria’s economic, social and environmental sustainability but the extent to which this can achieved is strongly dependent institutional framework, investment, incentives and information policies. / Program: Masterutbildning i energi- och materialåtervinning

[pt] Com o aumento das restrições às emissões veiculares e uma busca contínua pela melhora no desempenho dos motores a combustão interna, a necessidade de realizar testes em bancos de prova de motor se torna cada vez maior. Porém, devido ao alto investimento inicial e custo de manutenção desses sistemas, a execução de ensaios confiáveis torna-se restrita a determinadas empresas e instituições acadêmicas. Neste cenário, o presente trabalho visa projetar, construir e integrar equipamentos e instrumentos, em sua grande maioria nacionais, através do desenvolvimento de um sistema de controle que seja capaz de operar o conjunto desenvolvido. O projeto pretende contribuir com a redução de custos dos bancos de prova e, ao mesmo tempo, possibilitar a realização de testes confiáveis. Serão descritas as etapas do projeto e construção de uma bancada para ensaios de motores de até 175 cv, 587 Nm e 4.620 rpm. Testes foram conduzidos a fim de verificar o comportamento do banco de provas em diferentes situações de operação. Os resultados obtidos mostram que o sistema é capaz de realizar os mais diversos ensaios que um banco de provas está sujeito com precisão e robustez. / [en] With increasing restriction on emission and a continuous search for improvement and development of new engines, a need for internal combustion engines test bed is becoming greater. However due to high initial investments and maintenance costs of these systems, the execution of reliable tests becomes restricted to certain companies and academic institutions. In this scenario, this present work aims at the integration of equipment and instruments, mostly national, by the development of a control system. This project aims to contribute with test benches cost reduction and at the same time, allow for reliable testing. Will be described the project steps of a test bench for engines up to 175 hp, 587 Nm and 4.620 rpm and will be shown the results obtained.

Since the late 19th century, the average temperature on Earth has risen by approximately 1.1 °C because of the increased carbon dioxide (CO2) and other man-made emissions to the atmosphere. The transportation sector is responsible for approximately 33% of the global CO2 emissions and 14% of the overall greenhouse gas emissions. Therefore, increasingly stringent regulations in the European Union require CO2 emissions to be lower than 95 gCO₂/km by 2020. In this regard, improvements in internal combustion engines (ICEs)must be achieved in terms of fuel consumption and CO2 emissions. Given that only up to 35% of fuel energy is converted into mechanical power, the wasted energy can be reused through waste heat recovery (WHR) technologies. Consequently, organic Rankine cycle (ORC) has received significant attention as a WHR technology because of its ability to recover wasted heat in low- to medium-heat sources. The Expansion machine is the key component in ORC systems, and its performance has a direct and significant impact on overall cycle efficiency. However, the thermal efficiencies of ORC systems are typically low due to low working temperatures. Moreover, supersonic conditions at the high pressure ratios are usually encountered in the expander due to the thermal properties of the working fluids selected which are different to water. Therefore, this thesis aims to design an efficient radial-inflow turbine to avoid further efficiency reductions in the overall system. To fulfil this aim, a novel design and optimisation methodology was developed. A design of experiments technique was incorporated in the methodology toexplorethe effects of input parameters on turbine performance and overall size. Importantly, performance prediction modelling by means of 1D mean-line modelling was employed in the proposed methodology to examine the performance of ORC turbines at constant geometries. The proposed methodology was validated by three methods: computational fluid dynamics analysis, experimental work available in the literature, and experimental work in the current project. Owing to the lack of actual experimental works in ORC-ICE applications, a test rig was built around a heavy-duty diesel engine at Brunel University London and tested at partial load conditions due to the requirement for a realistic off-high representation of the performance of the system rather than its best (design) point, while taking into account the limitation of the engine dynamometer employed. Results of the design methodology developed for this projectpresented an efficient single-stage high-pressure ratio radial-inflow turbine with a total to static efficiency of 74.4% and an output power of 13.6 kW.Experimental results showed that the ORC system had a thermal efficiency of 4.3%, and the brake-specific fuel consumption of the engine was reduced by 3%. The novel meanlineoff designcode (MOC) was validated with the experimental works from three turbines. In comparison with the experimental results conducted at Brunel University London, the predicted and measured results were in good agreement with a maximum deviation of 2.8%.

A modelagem de motores a combustão interna deve grande parte de sua importância ao uso de unidades de controle eletrônicas que buscam gerenciar as funções do motor. De forma a fornecer melhor suporte para o projetista de controle, a modelagem oferece informações que servem de planta, sobre a qual estratégias de controle serão desenvolvidas. Nesta dissertação, procurou-se estudar e modelar cinco fenômenos: a admissão de ar e de combustível, a produção de energia efetiva através da combustão, a evolução térmica do motor e o comportamento dos gases no sistema de exaustão. Investigou-se também, em todos estes fenômenos, a influência do uso de composição variada gasolina/etanol. Na admissão de ar, buscou-se estudar como a abertura da válvula borboleta e a velocidade do motor influenciam no fluxo de ar admitido, ponderando esta grandeza através de um fator de correção denominado eficiência volumétrica. Na admissão de combustível, no caso modelada para motores com injeção indireta na porta, procurou-se explanar quantitativamente sobre os diversos aspectos que influenciam a evaporação do combustível. Na geração de energia útil, priorizou-se a análise de como as características do motor e da combustão afetam a produção de torque. Na evolução térmica do motor, examinaram-se os principais fluxos energéticos do motor e os aspectos que os influenciam. Ademais, foram executadas as validações dos modelos levantados para o motor EA 111 VHT 1.6l. Os resultados, com seus respectivos erros, podem ser encontrados neste trabalho. / The internal combustion engine modeling owes big part of its importance to the use of electronic control units that aim to manage the engine functions. To provide better support to the control designer, the modeling offers information that can compose the plant, on which control strategies will be developed. In this master thesis, it was sought to study and to model five phenomena: the air intake and the fuel admission, the effective energy production from the combustion, the engine thermic evolution and the gas behavior in the exhaust system. It was also considered how the influence of the gasoline/ethanol varied composition affects all these phenomena. In the air intake, it was studied how the butterfly valve opening and the engine speed influence the intake air flow, pondering this variable through a correction factor named volumetric efficiency. In the fuel admission, in the case of this study modelled for port-fuel injection engines, it was attempted to explain quantitatively the many aspects that influence the fuel evaporation. In the mechanical energy generation, it was prioritized the analysis about how the engine and combustion characteristics affect the torque production. In the engine thermic evolution, it was examined the major energy flows and the aspects that influence them. Also, the validations of the models raised for the EA 111 VHT 1.6l engine were executed. The results, with its respective errors, can be found in this work.