Дисертації з теми "Specific fuel consumption"

Purpose of this project is a) the evaluation of the Thrust Specific Fuel Consumption (TSFC) of jet engines in cruise as a function of flight altitude, speed and thrust and b) the determination of the optimum cruise speed for maximum range of jet airplanes based on TSFC characteristics from a). Related to a) a literature review shows different models for the influence of altitude and speed on TSFC. A simple model describing the influence of thrust on TSFC seems not to exist in the literature. Here, openly available data was collected and evaluated. TSFC versus thrust is described by the so-called bucket curve with lowest TSFC at the bucket point at a certain thrust setting. A new simple equation was devised approximating the influence of thrust on TSFC. It was found that the influence of thrust as well as of altitude on TSFC is small and can be neglected in cruise conditions in many cases. However, TSFC is roughly a linear function of speed. This follows already from first principles. Related to b) it was found that the academically taught optimum flight speed (1.316 times minimum drag speed) for maximum range of jet airplanes is inaccurate, because the derivation is based on the unrealistic assumption of TSFC being constant with speed. Taking account of the influence of speed on TSFC and on drag, the optimum flight speed is only about 1.05 to 1.11 the minimum drag speed depending on aircraft weight. The amount of actual engine data was extremely limited in this project and the results will, therefore, only be as accurate as the input data. Results may only have a limited universal validity, because only four jet engine types were analyzed. One of the project's original value is the new simple polynomial function to estimate variations in TSFC from variations in thrust while maintaining constant speed and altitude.

The possibilities to simulate fuel consumption and optimize a vehicle's powertrain to fit to the customer's needs are great strengths in the competitive bus industry where fuel consumption is one of the main sales arguments. In this master's thesis, bus specific powertrain component models, used to simulate and predict fuel consumption, are validated using measured data collected from buses.

Additionally, a sensitivity analysis is made where it is investigated how errors in the powertrain parameters affect fuel consumption. After model improvements it is concluded that the library components can be used to predict fuel consumption well.

During the work, possible model uncertainties which affect fuel consumption are identified. Hence, this study may serve as foundation for further investigation of these uncertainties.

Made available in DSpace on 2014-06-11T19:24:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-05Bitstream added on 2014-06-13T18:52:25Z : No. of bitstreams: 1 masiero_fc_me_botfca.pdf: 638059 bytes, checksum: abfe7790012d582df70c55bce95376dd (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O trator agrícola é a principal fonte de potência utilizada na agricultura e a maioria dos novos modelos disponíveis no mercado apresenta tração dianteira auxiliar (TDA). A preferência pelos tratores com tração dianteira auxiliar é devido à sua maior capacidade de tração, principalmente em condições trativas adversas e, sobretudo pela relação benefício e custo ser positiva e maior que os outros modelos. Esse trabalho foi realizado com o objetivo de avaliar o rendimento dinâmico na barra de tração de tratores agrícolas com tração dianteira auxiliar (4x2 TDA) em diferentes condições de superfície trativa comparando-os com os valores teóricos e práticos da bibliografia (“Fator 0,86” de Wendel Bowers e norma D497.4 ASAE, 1999) e determinar o rendimento dinâmico na barra para a superfície de solo com cobertura vegetal, pois existe pouca bibliografia e é uma realidade no Brasil com o plantio direto na palha. Avaliaram-se onze tratores agrícolas em diversas condições de ensaio de campo e condições de superfície, variando-se o tipo construtivo e modelos de conjunto de pneus, pressões de inflação dos pneus, relações entre o peso e potência do motor e velocidade teórica de deslocamento. Os dados de rendimento máximo na barra de tração do trator obtidos nos ensaios foram arranjados em grupos, obtendo-se o rendimento dinâmico médio na barra de tração e desvio padrão para cada condição de superfície. Foram coletados os dados para o cálculo do rendimento na barra de tração do trator, velocidade de deslocamento, patinagem das rodas dianteiras e traseiras do trator, consumo de combustível, força de tração e potência disponível na barra de tração.a realização do experimento, utilizou-se a Unidade Móvel de Ensaio...
The agricultural tractor is the main power source used in the agriculture and the most of available new tractor models in the marketing present auxiliary front drive (4WD). The preference for the 4WD tractors is due to biggest traction capacity, mainly in adverse tractive conditions and, mainly for the relationship benefit and cost to be positive and larger than the other models. This research was accomplished with the objective to evaluate the dynamic drawbar performance of several agricultural tractors 4WD in different surface condition (concrete, firm soil and tilled soil) comparing them with the theoretical and practical values of the bibliography (Wendel Bowers 0.86 Factor and D497.4 ASAE standard, 1999) and to determine the dynamic drawbar performance for the soil surface with vegetable covering, that doesn't exist in the bibliography and it is a reality in Brazil with the minimum cultivate. Eleven agricultural tractors were evaluated all 4WD in several field test conditions and surface conditions, being varied the tire constructive type and models, tire inflation pressures, relationships between the weight and engine power and forward speed. The maximum tractor drawbar performance obtained in the tests was arranged in groups, being obtained the medium dynamic drawbar... (Complete abstract click electronic access below)

Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Thesis: S.M. in Naval Architecture and Marine Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages [71a]-[71b]).
The dynamic operational nature of naval power and propulsion requires Ship Design and Program Managers to design and select prime movers using a much more complex speed profile rather than typical of commercial vessels. The inherently reduces the overall efficiency of the plant as operated in comparison to its potential. The fuel consumption of prime movers is a multi-variable function of power demand and rotational speed. Mechanically coupled power and propulsion arrangements constrain this two degree of freedom relationship by removing the independence of the speed parameter. Fixed frequency power generation requires a constant prime mover speed that has a narrow power band for optimal fuel consumption. Likewise, geared propulsion arrangements restrict the prime mover's speed to a dependence on the combined propulsor thrust-hull resistance performance which generally follows a cubic function. Optimal fuel consumption, however, involves matching the load's efficiency performance to that of the prime mover. This requires the rotational speed of the prime mover to be an independent variable with the freedom to adjust to the lowest specific fuel consumption for the demanded power. Variable frequency drive (VFD) concepts offer relief of this constraint but at a cost in the form of increased power conversion and control support system footprints. The ever increasing and complex demands for electrical power increases the motivation and interest in innovative technologies that improving current design concepts. Incorporating doubly fed electric machines (DFEM) into the power and propulsion design architecture enables the efficiency results of a VFD system but with a smaller conversion and control support footprint. The Navy has invested resources into research and development of several electric power and propulsion technologies enabling deployment of VFD systems on a handful of ship classes. The wind power generation industry has matured many aspects of DFEM technology. Leveraging this experience into naval engineering applications could help facilitate additional platform types and sizes to benefit from the operational advantages of integrated electrical architectures. Applying DFEM concepts to naval engineering requires a horizontal transfer of the body of knowledge. Researchers in the field of DFEM technology need to gain a better understanding of the intricacies of integrating a marine vessel's engineering plant with the vessel's designed purpose. New methods of analysis tailored specifically to marine power and propulsion require development for the technology to be properly assessed. This study outlines the various issues challenging ship designers and explains the manner in which DFEM research can be continued in naval engineering. Finally a method of examining a prime mover's fuel consumption is developed to provide a three-dimensional "fuel map" surface relationship of power-to-speed-to-fuel consumption. This thesis will serve as a building block supporting further DFEM power and propulsion concept analysis.
by Michael R. Rowles, Jr.
Nav. E.
S.M. in Naval Architecture and Marine Engineering

Orientador: Kléber Pereira Lanças
Banca: Alberto Kazushi Nagaoka
Banca: Paulo Roberto Arbex Silva
Resumo: O trator agrícola é a principal fonte de potência utilizada na agricultura e a maioria dos novos modelos disponíveis no mercado apresenta tração dianteira auxiliar (TDA). A preferência pelos tratores com tração dianteira auxiliar é devido à sua maior capacidade de tração, principalmente em condições trativas adversas e, sobretudo pela relação benefício e custo ser positiva e maior que os outros modelos. Esse trabalho foi realizado com o objetivo de avaliar o rendimento dinâmico na barra de tração de tratores agrícolas com tração dianteira auxiliar (4x2 TDA) em diferentes condições de superfície trativa comparando-os com os valores teóricos e práticos da bibliografia ("Fator 0,86" de Wendel Bowers e norma D497.4 ASAE, 1999) e determinar o rendimento dinâmico na barra para a superfície de solo com cobertura vegetal, pois existe pouca bibliografia e é uma realidade no Brasil com o plantio direto na palha. Avaliaram-se onze tratores agrícolas em diversas condições de ensaio de campo e condições de superfície, variando-se o tipo construtivo e modelos de conjunto de pneus, pressões de inflação dos pneus, relações entre o peso e potência do motor e velocidade teórica de deslocamento. Os dados de rendimento máximo na barra de tração do trator obtidos nos ensaios foram arranjados em grupos, obtendo-se o rendimento dinâmico médio na barra de tração e desvio padrão para cada condição de superfície. Foram coletados os dados para o cálculo do rendimento na barra de tração do trator, velocidade de deslocamento, patinagem das rodas dianteiras e traseiras do trator, consumo de combustível, força de tração e potência disponível na barra de tração.a realização do experimento, utilizou-se a Unidade Móvel de Ensaio... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The agricultural tractor is the main power source used in the agriculture and the most of available new tractor models in the marketing present auxiliary front drive (4WD). The preference for the 4WD tractors is due to biggest traction capacity, mainly in adverse tractive conditions and, mainly for the relationship benefit and cost to be positive and larger than the other models. This research was accomplished with the objective to evaluate the dynamic drawbar performance of several agricultural tractors 4WD in different surface condition (concrete, firm soil and tilled soil) comparing them with the theoretical and practical values of the bibliography (Wendel Bowers "0.86 Factor" and D497.4 ASAE standard, 1999) and to determine the dynamic drawbar performance for the soil surface with vegetable covering, that doesn't exist in the bibliography and it is a reality in Brazil with the minimum cultivate. Eleven agricultural tractors were evaluated all 4WD in several field test conditions and surface conditions, being varied the tire constructive type and models, tire inflation pressures, relationships between the weight and engine power and forward speed. The maximum tractor drawbar performance obtained in the tests was arranged in groups, being obtained the medium dynamic drawbar... (Complete abstract click electronic access below)
Mestre

Zapfluft und Wellenleistung wird den Triebwerken entnommen, um die Energie für beispielsweise die Kraftstoffpumpen, das Inflight Entertainment oder die Flügelvorderkantenenteisung zu erzeugen. Diese Energiegenerierung, hat einen Anstieg des Kraftstoffverbrauches zur Folge. Es hat sich herausgestellt, dass die Stelle der Zapfluftentnahme einen starken Einfluss auf den Gradienten des Brennstoffverbrauches hat. Das Projekt beschäftigt sich mit zwei- und dreiwelligen Turbofantriebwerken und untersucht an ihnen, die Effekte der Leistungsnahmen. Als Simulationssoftware wurde GasTurb 8.0 eingesetzt und auf die integrierten Triebwerkskonfigurationen zurückgegriffen. Ziel der Arbeit ist die Ermittlung einer mathematischen Beziehung zur Berechnung des zusätzlichen Kraftstoffmassenstromes infolge einer Zapfluft- oder Wellenleistungsentnahme. So stellt sich die Frage, welche Triebwerksparameter dafür berücksichtigt werden müssen. Eine Wellenleistungsentnahme verursacht beispielsweise einen linearen Anstieg des spezifischen Kraftstoffverbrauches. Ist diese Zunahme, identisch mit der einer Zapfluftentnahme? Am Ende der Kapitel werden die Ergebnisse mit Literaturwerten verglichen und versucht Tendenzen zu erkennen bzw. bestehende zu erhärten.

In the development of modern rotorcraft vehicles, many unique challenges emerge due to the highly coupled nature of individual rotorcraft design disciplines therefore, the use of an integrated product and process development (IPPD) methodology is necessary to drive the design solution. Through the use of parallel design and analysis, this approach achieves the design synthesis of numerous product and process requirements that is essential in ultimately satisfying the customers demands. Over the past twenty years, Georgia Techs Center for Excellence in Rotorcraft Technology (CERT) has continuously focused on refining this IPPD approach within its rotorcraft design course by using the annual American Helicopter Society (AHS) Student Design Competition as the design requirement catalyst. Despite this extensive experience, however, the documentation of this preliminary rotorcraft design approach has become out of date or insufficient in addressing a modern IPPD methodology. In no design discipline is this need for updated documentation more prevalent than in propulsion system design, specifically in the area of gas turbine technology. From an academic perspective, the vast majority of current propulsion system design resources are focused on fixed-wing applications with very limited reference to the use of turboshaft engines. Additionally, most rotorcraft design resources are centered on aerodynamic considerations and largely overlook propulsion system integration. This research effort is aimed at bridging this information gap by developing a preliminary turboshaft engine design methodology that is applicable to a wide range of potential rotorcraft propulsion system design problems. The preliminary engine design process begins by defining the design space through analysis of the initial performance and mission requirements dictated in a given request for proposal (RFP). Engine cycle selection is then completed using tools such as GasTurb and the NASA Engine Performance Program (NEPP) to conduct thorough parametric and engine performance analysis. Basic engine component design considerations are highlighted to facilitate configuration trade studies and to generate more detailed engine performance and geometric data. Throughout this approach, a comprehensive engine design case study is incorporated based on a two-place, turbine training helicopter known as the Georgia Tech Generic Helicopter (GTGH). This example serves as a consistent propulsion system design reference highlighting the level of integration and detail required for each step of the preliminary turboshaft engine design methodology.

This thesis deals with the use of the tractor in agricultural transport. The first part describes the current status in construction of tractor engines, transmissions and chassis that are used in tractors suitable for transport. The theoretical section includes an overview of the legislative requirements that must be followed for the tractor kits in transport on the road. The main objective of this thesis was to evaluate a measuring of fuel consumption and efficiency of the tractor JCB Fastrac 185-65 with two flatbed trailers. For this purpose was created the methodics off terrain measurement, which were carried out for different operation modes of the engine. The results were tabular and graphical processing including determining the accuracy of the method by calculating the relative error of measurement. For comparison a theoretical calculation of the consumed fuel was made. The aim of the measurements was to demonstrate fuel-saving during operation engine in the economic field and get an overview about fuel consumption and efficiency kits.

The thesis deals with the current situation in the construction of tractors, particularly engines and accessories. The work includes a methodology for measuring tractor rigs in traffic as well as methodology for plough/plow kits measuring. The measured values were tabulated, graphically presented and analysed. The thesis provides an overview of the issue of the combustion engine load placed on the engine by working conditions in transport, during primary soil tillage with different modes of operation of the tractor set. The thesis aim is to find out the practical effect of the engine load on the monitored parameters and to indicate possibilities for achieving higher efficiency in tractor units with minimum fuel performance

Der weltweit steigende Mobilitätsbedarf führt in der Zukunft zur weiteren Zunahme des Primärenergiebedarfs. Die Rohstoffvorräte unserer Erde sind begrenzt. Rohstoffe, die heute verbraucht werden, stehen zukünftigen Generationen nicht mehr zur Verfügung. Die sparsame und effiziente Nutzung der Ressourcen stellt deshalb den Schlüssel zu einer nachhaltigen Entwicklung dar. Im Mittelpunkt steht dabei der Energieverbrauch. Vor allem die Industrieländer stehen vor der Herausforderung, ihren Verbrauch an begrenzten Energierohstoffen Schritt für Schritt zurückzufahren. Der Wirtschaftsbereich der Europäischen Union kann dabei eine positive Bilanz vorweisen. Eingeschlossen in diese Bilanz ist der Verkehrsbereich. Die modernen Fahrzeugflotten konnten durch die ständige Weiterentwicklung den Streckenkraftstoffverbrauch und die Abgasemissionen erheblich absenken. Eine Entwicklung, die noch nicht am Ende ist. Trotz dieser positiven Tendenz gerät die globale Bilanz durch eine dramatische Zunahme der Fahrzeugflotten, besonders in den Entwicklungsländern, kontinuierlich in eine Schieflage. Die Energieverbräuche steigen und die Ressourcen der Energieträger Öl, Gas und Kohle nehmen ab. Es ist bekannt, dass weltweit besonders in hochentwickelten Industrieländern dieser Entwicklung durch Alternativ-Konzepte entgegengesteuert wird. Im Verkehrsbereich sind dies unter anderem veränderte Fahrzeugkonzepte (z. B. Hybridfahrzeuge) sowie die mittel- und längerfristige Substitution der konventionellen, mineralölstämmigen Kraftstoffe durch Erdgaskraftstoffe (SynFuel, nach der Shell-Mittel-Destillat-Synthese, SMDS, hergestellt) oder Kraftstoffe (Sun Fuel) aus regenerativen Energieträgern wie Restholz, Energiepflanzen oder Biomüll. Diese Entwicklungen werden durch eine permanente Reduzierung der Abgasemissionen von verbrennungsmotorisch angetriebenen Fahrzeugen begleitet. Insbesondere sind dies einerseits die limitierten Schadstoffe, welche in den einzelnen Ländern gesetzlich verankert sind, und andererseits die CO2-Emission, die z. B. noch auf einer freiwilligen Selbstverpflichtung der Automobilindustrie (in Deutschland 140 g/km CO2 – Ausstoß) basieren. Kapitel 1: Einführung 2 Alle diese Entwicklungen gilt es im Voraus abzuschätzen bzw. mit fundierten Betrachtungen in den Entwicklungsprozess einzuordnen. Dies gilt besonders für solche Länder, z. B. Ägypten, die den Technikfortschritt aus ökonomischer und ökologischer Betrachtung in sehr kurzer Zeit einzuführen haben. Die Simulationswerkzeuge aller Art werden bekannterweise dazu genutzt, um Fehlentwicklungen zu vermeiden. Je nach Aufgabe und Zielstellung sind diese Werkzeuge fachgerecht anzupassen und zu verifizieren. Im Speziellen werden konventionelle und alternative Antriebskonzepte für Fahrzeuge der verschiedensten Einsatzbedingungen mit einem Simulationswerkzeug bewertet. 1.1 Aufgabenstellung und Zielstellung

Made available in DSpace on 2017-07-10T15:14:29Z (GMT). No. of bitstreams: 1 DissertacaoMarcioRRigotte.pdf: 1614115 bytes, checksum: 34d26d4df31cfcd99ebf450c783bee96 (MD5) Previous issue date: 2014-02-14
The rising demand for energy, coupled with its high cost and the search for sustainability propitiated in recent years an increase in demand for renewable biofuels, including biodiesel. Although Brazil, and specifically Paraná, present agricultural vocation, with diversity of raw materials for biodiesel production, it remains tied to demand compulsory. This work aimed to evaluate the energetic performance of an engine-generator set using diesel oil and biodiesel of different feedstocks. The experiment was conducted in the Experimental Nucleus for Agricultural Engineering (NEEA), State University of West Paraná (UNIOESTE), located in Cascavel - Paraná, using entirely randomized design. The treatments were diesel oil, and three different types of biodiesel (crambe, soybean and waste frying oil) being used pure biodiesel (B100) and the binary blends B10, B20 and B50. The resistive loads used were 1, 2, 3, 4 and 5 kW for each type of fuel, a total of five replications. Among other observations, we evaluated the heating value, specific fuel consumption (CE) and energy efficiency (EE). The best CE was diesel with 0,349 Kg KW h-1 in the load 5 KW, followed by BC20-2 with 0,524 Kg kW h-1 and BC50-3 with 0,433 Kg kW h-1. Biodiesel has the CE nearest of the diesel with increasing resistive load, indicating that its use in operation closest the rated capacity is more efficient. Among the types of biodiesel, the crambe oil showed lower CE, with some values without significant differences (Tukey 5%) of the diesel CE, as BC20-4 with 0,383 Kg kW h-1 and BC10-5 with 0,367 Kg KW h-1. The best EE were DI-5 25,6%, BC100-5 25,5%, BC50-5 25,0%, BS100-5 24,8% and BORF100-5 24,6%. Pure biodiesel (B100) tends to show best EE that the binary blends used. The BC100 showed EE of 9,9 17,8, 21,8, 24,3 and 25,5% respectively for resistive load of 1, 2, 3, 4 and 50 KW. In the range of biodiesel evaluated, crambe oil obtained EE closer to diesel, and the BC100 exceeded diesel EE to the loads 2, 3 and 4
A crescente demanda por energia, associada a seus elevados custos e a busca por sustentabilidade propiciaram nos últimos anos um aumento na procura por biocombustíveis renováveis, dentre eles o biodiesel. Apesar do Brasil, e especificamente o Paraná, apresentarem vocação agrícola, com diversidade de matérias-primas para obtenção de biodiesel, esta permanece atrelada a demanda compulsória. Este trabalho buscou avaliar o desempenho energético de um conjunto motor-gerador utilizando diesel de petróleo e biodiesel de diferentes matérias primas. O experimento foi conduzido no Núcleo Experimental em Engenharia Agrícola (NEEA), da Universidade Estadual do Oeste do Paraná (UNIOESTE), Cascavel Paraná, utilizando delineamento experimental inteiramente casualizado. Os tratamentos utilizados foram o diesel de petróleo, e três diferentes tipos de biodiesel (crambe, soja e óleo residual de fritura), sendo o biodiesel utilizado puro (B100) e nas misturas binárias B10, B20 e B50. As cargas resistivas utilizadas foram de 1, 2, 3, 4 e 5 KW para cada tipo de combustível, com total de cinco repetições. Entre outras observações, foi avaliado o poder calorífico, o consumo específico (CE) e a eficiência energética (EE). O melhor CE foi o diesel com 0,349 Kg KW h-1 na carga 5 KW, seguido por BC20-2 com 0,524 Kg KW h-1 e o BC50-3 com 0,433 Kg KW h-1. O biodiesel apresenta CE mais próximo do diesel com o aumento da carga resistiva, indicando que sua utilização em operações mais próxima da capacidade nominal é mais eficiente. Dentre os tipos de biodiesel, o de óleo de crambe apresentou menor CE, com alguns valores sem diferenças significativas (Tukey 5%) do CE do diesel, como o BC20-4 com 0,383 Kg KW h-1 e o BC10-5 com 0,367 Kg KW h-1. As melhores EE foram DI-5 25,6%, BC100-5 25,5%, BC50-5 25,0%, BS100-5 24,8% e BORF100-5 24,6%. O biodiesel puro (B100) tende a apresentar melhor EE que as misturas binárias utilizadas. O BC100 apresentou EE de 9,9 17,8 21,8 24,3 e 25,5% respectivamente para as cargas resistivas de 1, 2, 3, 4 e 5 KW. Na gama de biocombustíveis avaliados, o de óleo de crambe obteve EE mais próxima ao do diesel, sendo que BC100 superou EE do diesel nas cargas 2, 3 e 4.

Research of the Aerothermopressor Cooling System of Charge Air of a Marine Internal Combustion Engine Under Variable Climatic Conditions of Operation / D. Konovalov, E. Trushliakov, M. Radchenko, H. Kobalava, V. Maksymov // Grabchenko’s Intern. Conf. on Advanced Manufacturing Processes. – Odessa, 2020. – P. 520–529.
Abstract. Principle of charge air cooling of the internal combustion engine with an aerothermopressor is proposed. It is implemented on the transport ship regular line. Arising thermogasdynamic compression allows increasing the air pressure. The aerothermopressor application in the charge air cooling systems makes it possible to reduce the power consumed by compressors, Nc by 3–10 %, thereby the engine power is increased by 1–3 % and the specific fuel consumption is decreased by 2–4 %. It is established that in case of increasing the ambient air temperature tamb at the turbocharger input the effect from the aerothermopressor used for cooling of the charge air is increased: the turbocharger power reduction DNC is increased with a corresponding increase in engine power and a decrease in specific fuel consumption. The relative (related to air flow) water mass flow is determined, which has to be injected at completely evaporated in a thermal overpressure: 0.02–0.05 (2–5 %).

Dissertação de Mestrado em Energia para a Sustentabilidade apresentada à Faculdade de Ciências e Tecnologia
O objetivo desta tese de mestrado é melhorar a compreensão do funcionamento e operação dos Motores de Combustão Interna (MCI) pelo profissional do setor de energia. O resultado deste trabalho é um programa computacional capaz de simular a operação de um motor de combustão interna e prever a sua potência e consumo específico de combustível bem como a emissão de gases de efeito de estufa. O utilizador do programa apenas terá de introduzir especificações básicas sobre o MCI para obter resultados concretos e fiáveis em um curto intervalo de tempo. A tese começa por introduzir os MCI e explicar a sua relevância, tanto a nível global como a curto, médio e longo prazo. De seguida, o modo de operação dos MCI é sucintamente descrito e os seus parâmetros principais identificados. Um modelo matemático baseado nos princípios físicos e químicos que regem o funcionamento do MCI é então construído e resolvido através de um programa de computador. O detalhe e o rigor da metodologia envolvida tanto na modelação matemática como na construção e execução do programa de computador servem como validação dos mesmos. Por último um conjunto de resultados é apresentado, interpretado e discutido. . . . . . . . . .
The purpose of this master’s thesis is to improve the understanding of the function and operation of the Internal Combustion Engine (ICE) by the energy sector professional. The outcome of this work is a computer program capable of simulating ICE operation and predict its power output and specific fuel consumption as well as its Green House Gas emissions. The program user will only have to introduce basic ICE information to obtain concrete and reliable results in a narrow time span.The thesis starts by introducing ICE’s and explaining their relevance on a global scale as well as over short, medium and long term. Next ICE operation is succinctly described, and its main parameters identified. A mathematical model based on ICE physical and chemical working principles is constructed and solved through a computer program. The detail and thoroughness involved in the mathematical modelling, the programming and computation serve as model and computer program validation. Finally, a set of results from the program is presented, interpreted, and discussed. . . . .

Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra
O objetivo deste trabalho consiste em otimizar o consumo específico de combustível ao freio do motor de combustão interna M3165 que propulsiona o Eco Veículo XC20i com o intuito de o tornar mais competitivo na participação das edições de 2014 da SHELL Eco marathon (SEM). Como enquadramento são apresentadas as linhas gerais da estrutura e regulamento da SEM na categoria onde se insere o Eco Veículo, assim como um resumo do histórico do veículo, que o levou à forma e performance atuais, e explicados de forma detalhada os contornos e procedimentos da realização dos ensaios experimentais em ambiente laboratorial. Seguidamente são apresentados os resultados das simulações numéricas realizadas em computador e dos testes experimentais, realizados em banco de ensaio, em que foi quantificado o efeito da utilização de diferentes óleos lubrificantes no motor e de algumas variáveis de operação deste, nomeadamente a temperatura do cárter, temperatura da cabeça do cilindro, tempos de injeção, riqueza da mistura ar-combustível, condições climatéricas, entre outros. A análise destes resultados permite perceber de que forma a combinação destas variáveis influencia o desempenho do motor, somando-se à experiência obtida nas edições anteriores, assim como permite o conhecimento mais pormenorizado de alguns componentes que, direta ou indiretamente, intervêm no bsfc do motor. Este conhecimento resulta numa melhor preparação para a prova, pois com a identificação das condições ótimas de funcionamento em termos térmicos permite promover alterações de materiais ou isolamento a curto prazo, aperfeiçoar a programação da centralina (ECU) do motor, adaptando-a a diferentes circunstâncias, definir a melhor estratégia de prova e melhorar a capacidade de intervenção imediata durante a competição sempre com o objetivo de minimizar o consumo e obter uma boa classificação.
The objective of this work is to optimize the brake specific fuel consumption of an internal combustion engine, the M3165, which drives the Eco Veículo XC20i in order to make it more competitive in the participation of the 2014 editions of the SHELL Eco marathon (SEM). As an introduction we present the outline of the structure and regulation of SEM in the category where the Eco Veículo is inserted, and a summary of the history of the vehicle, which led to the present form and performance, and are explained in detail the contours and procedures of the experimental tests in the laboratory. Following, are presented the results of numerical simulations performed in a digital computer and of experimental tests conducted in an engine test bench, in which the effect of using different lubricants in the engine and some variables of it operation were quantified, namely the crankcase temperature, cylinder head temperature, injection duration, equivalence ratio of the air-fuel mixture, ambient conditions, among others. The analysis of these results allows understanding how the combination of these variables influences the engine performance, adding to the experience gained in previous editions as well as allows more detailed knowledge of some components that directly or indirectly influences the engine’s bsfc. This knowledge results in better preparedness for the competition, because the identification of the optimal operating thermal conditions, allows to promote changes in materials or thermal insulation in the short term, to improve the ECU programming, adapting it to different circumstances, to define the best race strategy and improves the capacity for immediate intervention during the competition, always aiming to minimize fuel consumption and get a good ranking.

Dissertação de mestrado integrado em Engenharia Mecânica
Os motores de combustão interna de ignição por compressão possuem geralmente maiores rendimentos que os motores de ignição comandada. No entanto, existem estratégias que permitem aumentar o rendimento dos motores de ignição comandada, podendo-se mesmo ultrapassar os rendimentos dos motores Diesel. Algumas destas estratégias passam pela variação da taxa de compressão e do tempo de aberturas de válvulas. O chamado Ciclo de Miller implementa ambas estas estratégias com o objetivo de conseguir a sobre-expansão dos gases de escape aproveitando melhor a sua entalpia. A redução da massa de ar a ser admitida ao motor em cada ciclo, característica do ciclo de Miller, pode ser conseguida por atraso no fecho das válvulas de admissão (LIVC – Late Intake Valve Closure) ou por adiantamento no fecho das válvulas de admissão (EIVC – Early Intake Valve Closure). Com a realização deste trabalho pretende-se alterar um motor BMW K75 adaptando-o de ciclo de Otto para ciclo de Miller de forma a garantir um melhoramento do rendimento e desenvolver um conceito de Range Extender, para carros elétricos, eficiente. A reduzida massa de ar admitida e a baixa velocidade de rotação do motor traduz-se numa queda de potência para 1/3 a 1/4 da potência original. Como nalgumas condições poderá ser necessário dispor de uma potência mais elevada, vai ser necessário um segundo ponto de funcionamento do motor a alta velocidade, optando-se assim por usar o sistema LIVC (o qual beneficia a eficiência volumétrica nestas condições), naturalmente sacrificando o rendimento. Foram estudadas e projetadas as alterações necessárias para a implementação do ciclo de Miller no motor BMW K75 através de um modelo teórico que permite calcular o rebaixamento do bloco necessário para a taxa de compressão retida desejada, assim como estimar a melhoria de rendimento esperado para os perfis de cames existentes (Dwell 50 e 60) e outros perfis que possam melhorar, ainda mais, a eficiência do motor. Foi selecionada, teoricamente, a configuração (rebaixamento do bloco e perfil do came de admissão) que maximizará o rendimento do motor. O presente trabalho testou detalhadamente o motor no seu estado original, depois de uma laboriosa preparação da instalação experimental. Futuramente deverá ser aperfeiçoada a configuração que proporcionará melhor rendimento pela comparação dos valores obtidos por ensaios experimentais do motor no ciclo de funcionamento original (ciclo de Otto) com os obtidos para o motor alterado (ciclo de Miller) para diferentes taxas de compressão e perfis de cames.
The internal combustion engines with compression ignition have higher efficiency than spark ignition engines. However, there are strategies that help to increase the efficiency of spark ignition engines, and even surpass the efficiency of diesel engines. Some of these strategies include the change in compression ratio and valve opening/closure time. The so-called Miller cycle implements both of these strategies in order to achieve the over-expansion of the exhaust gases, better using their enthalpy. Reducing the mass of air to be admitted to the engine in each cycle, characteristic of Miller cycle, can be achieved by delayed closure of the intake valves ( LIVC - Late Intake Valve Closure ) or anticipating the closing the intake valves ( EIVC -Early Intake Valve Closure). With this work we intend to change a BMW K75 engine adapting it from an Otto cycle to a Miller cycle to ensure an improvement in the thermal efficiency and develop a concept of efficiency-based Range Extender for electric vehicles. The reduced mass of air admitted and the low speed of the engine translates into a power drop to 1/3 to 1/ 4 of the original power. Under some conditions, as it may be necessary to have a higher power, a second point of engine operation at high speed will be necessary, so opting to use the system LIVC (which benefits the volumetric efficiency in these conditions), naturally sacrificing performance. The design of the necessary changes for the implementation of the Miller cycle engine were studied and prepared through a theoretical model that predicts the required lowering of the block for the desired trapped compression ratio. This model was also used for estimating the efficiency improvement obtained with each one of the newly manufactured camshaft profiles (Dwell 50 and 60) and other possible profiles that may improve even more the engine efficiency. The present study tested the original engine in detail, after a laborious preparation of the experimental setup. In the future, the configuration which will provide the best performance should be studied by comparing the values obtained by experimental trials of the original engine (Otto cycle) with those obtained with the modified engine (Miller cycle) for different compression ratios and cams profiles.