Academic literature on the topic 'Otto-cycle engine'
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Journal articles on the topic "Otto-cycle engine"
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Sasaki, Senichi. "Dual-Fuel Engine, Otto Cycle and Diesel Cycle." Journal of The Japan Institute of Marine Engineering 44, no. 6 (2009): 978. http://dx.doi.org/10.5988/jime.44.978.
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Diskin, David, and Leonid Tartakovsky. "Efficiency at Maximum Power of the Low-Dissipation Hybrid Electrochemical–Otto Cycle." Energies 13, no. 15 (August 1, 2020): 3961. http://dx.doi.org/10.3390/en13153961.
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A novel analytical method was developed for analysis of efficiency at maximum power of a hybrid cycle combining electrochemical and Otto engines. The analysis is based on the low-dissipation model, which relates energy dissipation with energy transfer rate. Efficiency at maximum power of a hybrid engine operating between two reservoirs of chemical potentials is evaluated. The engine is composed of an electrochemical device that transforms chemical potential to electrical work of an Otto engine that uses the heat generated in the electrochemical device and its exhaust effluent for mechanical work production. The results show that efficiency at maximum power of the hybrid cycle is identical to the efficiency at maximum power of an electrochemical engine alone; however, the power is the product of the electrochemical engine power and the compression ratio of the Otto engine. Partial mass transition by the electrochemical device from the high to the low chemical potential is also examined. In the latter case, heat is generated both in the electrochemical device and the Otto engine, and the efficiency at maximum power is a function of the compression ratio. An analysis performed using the developed method shows, for the first time, that, in terms of a maximal power, at some conditions, Otto cycle can provide better performance that the hybrid cycle. On the other hand, an efficiency comparison at maximum power with the separate Otto-cycle and chemical engine results in some advantages of the hybrid cycle.
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Oh, Jungmo, Kichol Noh, and Changhee Lee. "A Theoretical Study on the Thermodynamic Cycle of Concept Engine with Miller Cycle." Processes 9, no. 6 (June 16, 2021): 1051. http://dx.doi.org/10.3390/pr9061051.
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The Atkinson cycle, where expansion ratio is higher than the compression ratio, is one of the methods used to improve thermal efficiency of engines. Miller improved the Atkinson cycle by controlling the intake- or exhaust-valve closing timing, a technique which is called the Miller cycle. The Otto–Miller cycle can improve thermal efficiency and reduce NOx emission by reducing compression work; however, it must compensate for the compression pressure and maintain the intake air mass through an effective compression ratio or turbocharge. Hence, we performed thermodynamic cycle analysis with changes in the intake-valve closing timing for the Otto–Miller cycle and evaluated the engine performance and Miller timing through the resulting problems and solutions. When only the compression ratio was compensated, the theoretical thermal efficiency of the Otto–Miller cycle improved by approximately 18.8% compared to that of the Otto cycle. In terms of thermal efficiency, it is more advantageous to compensate only the compression ratio; however, when considering the output of the engine, it is advantageous to also compensate the boost pressure to maintain the intake air mass flow rate.
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Pandit, Tanmoy, Pritam Chattopadhyay, and Goutam Paul. "Non-commutative space engine: A boost to thermodynamic processes." Modern Physics Letters A 36, no. 24 (August 10, 2021): 2150174. http://dx.doi.org/10.1142/s0217732321501741.
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We introduce quantum heat engines that perform quantum Otto cycle and the quantum Stirling cycle by using a coupled pair of harmonic oscillator as its working substance. In the quantum regime, different working medium is considered for the analysis of the engine models to boost the efficiency of the cycles. In this work, we present Otto and Stirling cycle in the quantum realm where the phase space is non-commutative in nature. By using the notion of quantum thermodynamics, we develop the thermodynamic variables in non-commutative phase space. We encounter a catalytic effect (boost) on the efficiency of the engine in non-commutative space (i.e. we encounter that the Stirling cycle reaches near to the efficiency of the ideal cycle) when compared with the commutative space. Moreover, we obtained a notion that the working medium is much more effective for the analysis of the Stirling cycle than that of the Otto cycle.
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Schiffgens, H. J., H. Endres, H. Wackertapp, and E. Schrey. "Concepts for the Adaptation of SI Gas Engines to Changing Methane Number." Journal of Engineering for Gas Turbines and Power 116, no. 4 (October 1, 1994): 733–39. http://dx.doi.org/10.1115/1.2906880.
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In a joint project of FEV Motorentechnik and Ruhrgas AG, the design of stoichiometric and lean-burn Otto engines was optimized by selective modifications to the design and operating parameters to accommodate changing methane numbers (LPG addition to CNG). Of particular importance was knock-free engine operation at a low NOx output to meet the requirements of the German Clean Air Code while concurrently achieving both high efficiencies and mean effective pressures. Based upon the results obtained, concepts for the control of Otto-cycle gas engines to accept changing methane numbers were developed. The newly developed gas engine control device allows these concepts to meet the requirement of the German Clean Air Code with economically viable conditions while preventing engine knock. Furthermore, the test results show that dedicated Otto-cycle gas engines can meet the most stringent emission limits for commercial vehicles while maintaining high efficiencies.
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Arabaci, Emre. "Performance analysis of a novel six-stroke otto cycle engine." Thermal Science, no. 00 (2020): 144. http://dx.doi.org/10.2298/tsci190926144a.
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In this study, a simulation model with finite time thermodynamics was presented for an Otto cycle six-stroke engine. In this six-stroke engine, two free strokes occur after the exhaust stroke. These free strokes cause the engine to have higher thermal efficiency. Due to high thermal efficiency, these six-stroke engines can be used in hybrid electric vehicles. In this study, the effect of residual gas fraction and stroke ratio on the effective power and effective thermal efficiency were investigated. In addition, heat balance was obtained for the engine and the use of fuel energy in the engine was examined with the help of performance fractions. In the simulation model, the results are quite realistic as the working fluid was assumed to consist of fuel-air-residual gases mixture.
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Naaktgeboren, Christian. "An air-standard finite-time heat addition Otto engine model." International Journal of Mechanical Engineering Education 45, no. 2 (February 8, 2017): 103–19. http://dx.doi.org/10.1177/0306419016689447.
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A classical thermodynamic model for spark-ignited internal combustion engine simulation in which the heat addition process that takes a finite amount of time to complete is presented along with an illustrative parameter sensibility case study. The model accounts for all air-standard Otto cycle parameters, as well as crank-connecting rod mechanism, ignition timing, engine operating speed, and cumulative heat release history parameters. The model is particularly suitable for engineering undergraduate education, as it preserves most of the air-standard assumptions, while being able to reproduce real engine traits, such as the decay of maximum pressure, power, and thermal efficiency at higher engine operating speeds. In terms of complexity, the resulting finite-time heat addition Otto cycle sits between the classical air-standard Otto cycle and the more involved air–fuel Otto cycle, that are usually introduced on more advanced mechanical engineering courses, and allows students to perform engine parameter sensibility studies using only classical, single phase, pure substance, undergraduate engineering thermodynamics.
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Chicurel, R. "A modified Otto cycle engine for fuel economy." Applied Energy 38, no. 2 (January 1991): 105–16. http://dx.doi.org/10.1016/0306-2619(91)90069-a.
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Willi, M. L., and B. G. Richards. "Design and Development of a Direct Injected, Glow Plug Ignition-Assisted, Natural Gas Engine." Journal of Engineering for Gas Turbines and Power 117, no. 4 (October 1, 1995): 799–803. http://dx.doi.org/10.1115/1.2815467.
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Conventional (Otto cycle) natural gas engines are limited in power and thermal efficiency relative to a diesel engine due to detonation and the need to run a nearly stoichiometric air/fuel ratio. Technology is under development to burn natural gas in a direct-injected diesel cycle that is not prone to detonation or air/fuel ratio control limitations. Direct-injected gas (DIG) technology will allow natural gas engines to match the power and thermal efficiency of the equivalent diesel-fueled engine. Laboratory development now under way is targeted for field experimental evaluation of a DIG 3516 engine in a 1500 kW road switcher locomotive. This paper will describe DIG 3516 engine component design and single and multicylinder performance development.
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Sharke, Paul. "Otto or Not, Here it Comes." Mechanical Engineering 122, no. 06 (June 1, 2000): 62–66. http://dx.doi.org/10.1115/1.2000-jun-4.
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This article highlights the new ignition schemes for Otto cycle engines that seem to be bound for extinction. Ever since Nicolaus Otto demonstrated the first working four-stroke engine in 1876, engineers have been struggling to come up with ways to sidestep a fundamental limitation of an otherwise stellar design. The reciprocating engine is capable of generating high pressure with reliable sealing, but the volume swept out by the piston has had to remain fixed. Small engines use less internal reciprocating mass than large ones, so the energy to overcome friction decreases as size drops. Small engines are lighter than big ones, too. By recirculating exhaust gases back into the combustion chamber, however, Mitsubishi uses the exhaust to reduce NOx. Because the air-to-fuel ratio is so high, the exhaust gases, which normally hinder combustion, can be as much as 70 percent of the cylinder volume. At the same time, Mitsubishi uses a lean NOx catalytic converter.
Dissertations / Theses on the topic "Otto-cycle engine"
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Barbosa, Cleiton Rubens Formiga. "Desempenho de um motor ciclo Otto com injeção direta de gás natural." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-05042005-104859/.
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Um motor ciclo Otto funcionando com injeção direta de gás natural, durante o curso de admissão, foi submetido a ensaios de plena carga em um dinamômetro corrente de Foucaut. Os resultados obtidos revelam um aumento de eficiência volumétrica do motor com injeção direta de GNC em relação à injeção indireta de GNC realizada no coletor de admissão, a montante da borboleta do acelerador. Na adaptação para operação com injeção direta de gás natural, as características técnicas do motor não foram alteradas. Um conjunto de injeção direta de gás natural, com gerenciamento eletrônico, foi inserido no cabeçote do motor de testes. Mantendo-se a pressão da linha de alimentação de gás natural constante, através de uma válvula redutora, a quantidade de combustível injetada no cilindro foi ajustada variando-se o tempo de abertura da válvula elétrica injetora de combustível. Dados de desempenho do motor são comparados, destacando-se os fatores que contribuem para este aumento relativo de eficiência volumétrica. Discute-se ainda, modificações a serem implementadas no motor visando maximizar sua potência com injeção direta de gás naturalOtto cycle engine direct injection natural gas, during the inlet stroke, submitted to runs with full power in a Foucaut dynamometer. The results obtained show a increase in the volumetric efficiency of the engine with natural gas direct injection when compared which natural gas injection apllied in the inlet manifold, upstream of the throttle butterfly. ln the conversion to natural gas direct injection, the technical characteristics of the were not changed. A kit for natural gas direct injection, with eletronic managment, was located on the cylinder head of the test engine. Maintaining the pressure constant in the natural gas fuel line, using a reduction valve. The mass of fuel injected into the cylinder was regulated, varying the opening time of the solenoid valve fuel injector. Engine performance data is compared, emphasizing the factors that contribute to this increase in relative volumetric efficiency. Modifications to be made to maximize the power of the engine with natural gas direct injection
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Fernandez, Breno Ortega. "Considerações sobre outros empregos do sensor de detonação para o controle eletrônico de motores ciclo Otto utilizando análise espectral." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-07112006-112508/.
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Este trabalho apresenta um estudo para a qualificação do sensor de detonação como elemento de realimentação para o sistema de controle eletrônico de motores de combustão interna. A metodologia proposta consiste no uso do sensor de detonação, previamente instalado pelo fabricante do motor com a finalidade de eliminar o indesejável efeito da combustão espontânea, para amostrar as vibrações mecânicas produzidas pelo motor em funcionamento. Tal vibração, resultado de massas em movimento e da oscilação natural do sistema excitado pela combustão, produz uma figura espectral na faixa de freqüências do som audível. O método proposto contempla ainda as variações espectrais das vibrações de um mesmo motor operando com diferentes misturas combustíveis.This dissertation analyses the suitability of using the knock sensor as a feedback element for the electronic control of internal combustion engines. The proposed approach consists of using the knock sensor, originally installed by the engine maker in order to eliminate the spontaneous combustion effect, to sample the mechanical vibration produced by the engine. This vibration, which results from the moving parts and the natural oscillation of the system in combustion, produces an output in the range of audible sound. This research contemplates using the spectral variation of that sound to estimate information about an engine operating with different fuel blends.
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Barragan, Neto Valter. "Simulação computacional em camisas de motor construídas em liga de alumínio silício." Universidade Presbiteriana Mackenzie, 2011. http://tede.mackenzie.br/jspui/handle/tede/1321.
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Previous issue date: 2011-09-27General Motors do Brasil
Automotive cylinder liners are mechanical components with the function of internal coating of the cylinder automotive engines. The liners have been made of cast iron, which meets the necessary requirements. The replacement of parts made of steel/ cast iron in aluminum alloys has been made with advantages not only in reducing weight as well as fuel consumption and emission of pollutants. This work has an objective to study the possibility to apply the cylinder liners built in aluminum and silicon alloy on engines with computer aided engineering help. The finite element method consists to generate a mathematical model with computational assistance, of geometry, representing several elements that have in common the node connection, forming the finite element, defined as a mesh. For each node the partial differential equations are solved by numerical methods. This study was aided by finite element software Hyperworks, where the mesh was generated and was exported to Abaqus where were performed the processing of input data. The starting point for the simulation of aluminum liners used in internal combustion engines was to define the format of the mesh for the engine block with less refinement, was chosen a mesh with tetrahedron elements of 4 nodes of with size ranging between 1 mm and 12 mm of edge element. The liners was designed with hexahedron elements of six nodes, which by definition are more consistent and have more accurate answers to the elements tetrahedrons and with a larger refinement, about 1 mm, both elements are first order elements with no nodes on edge s midpoint . In function of the process of manufacturing the liners to be cast by centrifugation, layers of elements were created to meet the variation in the amount of the silicon liner, which in turn affects the physical properties of the liner along the thickness of the wall. With this model it was possible to show the viability of applying these liners in engine blocks of cast iron. The analysis has shown that a prototype could be build in order to test the cylinder liners application and also test the wear of the cylinder liner.
Camisas de cilindro automotivo são componentes mecânicos com a função de revestir internamente os cilindros dos motores automotivos. As camisas de cilindros têm sido feitas de ferro fundido, que atende os requisitos necessários de desgaste e rigidez. A substituição de partes feitas em aço e ferro fundido por ligas de alumínio em veículos têm vantagens não só na diminuição de peso como também no consumo de combustível e emissão de poluentes. Este trabalho teve por objetivo estudar a viabilidade da aplicação de camisas constituídas em liga de alumínio e silício em motores com o auxilio de engenharia assistida por computador. O método de modelagem em elementos finitos consiste em gerar um modelo matemático auxiliado por computador, da geometria, constituída por vários elementos que têm em comum nós de ligação formando os elementos finitos, assim definidos por malha. Para cada um dos nós são resolvidas as equações diferenciais parciais por métodos numéricos. O estudo em elementos finitos foi auxiliado pelos softwares Hyperworks, onde foi gerada a malha e exportada para o Abaqus onde foi realizado o processamento dos dados de entrada. O ponto de partida para a simulação das camisas de alumínio aplicadas em motores de combustão interna foi definir a formato da malha para o bloco com um menor refinamento, foi então escolhida uma malha com elementos tetraédricos de quatro nós de tamanho variando entre 1 mm e 12 mm de aresta de elemento. A camisa foi elaborada com elementos hexaédricos de seis nós, que por definição são mais fiéis e possuem respostas mais precisas que os elementos tetraédricos, e com um refinamento maior, cerca de 1 mm, ambos de primeira ordem sem nós intermediários nas arestas. Em função do processo de fabricação da camisa ser a fundição por centrifugação, camadas de elementos foram criadas a fim de satisfazer a variação da quantidade de silício da camisa, que por sua vez afeta as propriedades físicas da camisa ao longo da espessura da parede. Com este modelo foi possível mostrar a viabilidade da aplicação dessas camisas em motores com blocos de ferro fundido. As análises mostraram que um protótipo poderá ser construído para testar a aplicação destas camisas e testá-las quanto ao desgaste.
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Costa, Fabiano Tadeu Mathias. "Estimação da relação ar-combustível utilizando o sinal de pressão no cilindro em um motor ciclo Otto a etanol." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-12022016-115907/.
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A crescente demanda de diminuição das emissões e redução do consumo dos motores de combustão interna exige a melhoria dos métodos para diagnose, em tempo real, e para melhor controle do processo de combustão. Portanto, é desejável determinar a relação ar-combustível sobre uma extensa faixa de condições de operação para obter um melhor controle do motor. Este trabalho apresenta a aplicação do Método dos Momentos para obtenção de um modelo de estimação da relação ar-combustível, através do sinal de pressão no cilindro, em um motor ciclo Otto a etanol. O modelo obtido permitirá o desenvolvimento de novos sistemas de controle utilizando como estratégia a pressão no cilindro.The increasing demands for low emission and low fuel consumption in internal combustion engines require improved methods for diagnosis, in real-time and best possible control of the combustion process. Therefore, determining air-fuel ratio over a wide range of engine operating conditions is desirable for better engine control. This work presents the Moment Method application for obtaining air-fuel ratio estimation model, by cylinder pressure sign, in Otto cycle engine powered by ethanol. The obtained model will allow the development of new control systems, for engine powered alcohol, using as strategy the cylinder pressure.
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Barros, Bruno Vinícius de menezes'. "Efeito da contrapressão e do resfriamento da turbina no desempenho de um motor diesel ottolizado para gás natural." Universidade Federal da Paraíba, 2015. http://tede.biblioteca.ufpb.br:8080/handle/tede/8976.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
The cost of the kWh at the peak hour in Brazil may be up to nine times higher than the one at normal hours. This fact has served as motivation for industries, shopping malls, hotels, and so on, to utilize electrical generators. These generator sets generally comprise Diesel engines. The problem is that the exhaust gases from these engines are very harmful to health. On the other hand, Natural Gas, thanks to its high calorific power and its low emissions, is considered a clean-burning alternative fuel. Therefore, the Diesel engines converted to Otto cycle may considerably reduce the environmental pollution. Such a conversion, however, may have in turbocharged engines backpressure effects that increase the temperature of the turbine, reducing the energy efficiency of the engine. The present study analyzes the result and consequences of the replacement of the original manifold by another with smoother curves, as well as the cooling effect on the engine performance of the turbine of a Perkins turbocharged model 1104C-44TAG2, converted to the Otto cycle. First, tests were made running the engine with its original manifold without any cooling, and then, having the turbine cooled with room air. After the replacement of the manifold, new teste were performed. Initially, without cooling the turbine or the manifold. Then, after the replacement of the manifold, other tests ventilating the turbine and the manifold were made. In each test, one has registered: the maximum operation power; temperature of the exhaust gases and the engine consumption in terms of the backpressure due to the manifold. All the tests were performed with the aid of a hydraulic dynamometer. It was noted that the use of the new manifold allowed the reduction on the backpressure. Concerning the maximum power registration there was no difference in terms of the original or the new manifold, because what had limited the power was the temperature on the turbine, which was set at 660 oC. Therefore, whenever the temperature reached this limit, the engine was deliberated stopped. This fact also explains why the ventilation has allowed higher engine powers. The new manifold resulted in fuel reductions.
O valor do kWh, no horário de pico, no Brasil, pode ser até nove vezes maior do que aquele cobrado, fora do dito período, estimulando a indústria, shopping centers, hotéis, etc. a fazerem uso de grupos geradores. Tais grupos são, em geral, compostos por motores a diesel e gerador elétrico. O lado negativo destes motores advém da larga poluição ambiental que produzem. Por sua vez, o Gás Natural, graças ao seu elevado poder calorífico e pela baixa contaminação, quando queimado, é considerado um combustível nobre, alternativo ao diesel. Assim, o uso de motores Diesel turbinados, convertidos para o ciclo Otto, pode reduzir significativamente a poluição ambiental. Nessa conversão, um dos aspectos observados é a influência da contrapressão causada pelo sistema de exaustão dos gases de escape, que contribui para o aumento da temperatura da turbina do motor convertido. O presente trabalho analisa os efeitos da substituição do coletor de escape original por outro, de curvas mais suaves, como também o resfriamento da turbina, no desempenho de um motor Perkins turboalimentado, modelo 1104C-44TAG2, ottolizado para gás natural. Os testes foram realizados com os dois coletores de escape, em operações com e sem refrigeração (por ventilação) da turbina e do coletor. A cada teste, eram avaliados: a potência máxima de operação, a temperatura dos gases de escape e o consumo do motor, em função da contrapressão do sistema de exaustão. Tais testes foram realizados, com o auxílio de um dinamômetro hidráulico, e os resultados mostraram que, de fato, houve uma redução da contrapressão, com a substituição do coletor. No entanto, o motor Perkins ottolizado respondeu, de forma semelhante, para os dois coletores, no que diz respeito à potência máxima alcançada, variando somente devido aos efeitos provocados com e sem resfriamento da turbina e do coletor. Deve-se observar, todavia, que a limitação no valor da potência deveu-se às temperaturas alcançadas pela turbina, de aproximadamente 660 °C. Assim, com resfriamento da turbina, o motor atingiu potências mais elevadas. Verificou-se, ainda, que a modificação do coletor contribuiu para a redução do consumo do motor.
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Ferraz, Fagner Barbosa. "Análise de desempenho de um motor diesel turboalimentado ottolizado para gás natural." Universidade Federal da Paraíba, 2014. http://tede.biblioteca.ufpb.br:8080/handle/tede/5384.
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Previous issue date: 2014-06-30Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
A large number of national companies has been using diesel gensets as an alternative to the electricity supplied by the local utility. Therefore, generators are used as an emergency power system or during peak hours. Peak hour in Brazil is between 5 to 10 p. m. As we know diesel engines contribute to the large increase in environmental pollution, since the diesel exhaust may contain fine particles associated with negative health effect, toxic air contaminants, as NOx and SOx. On the other hand, Natural gas is considered as a suitable choice rather than the use of diesel, because it possesses high calorific power, clean burning, and proper octane level for Otto cycle engine. The present work deals with the performance analysis of a Perkins engine turbocharged, diesel, model 1104C-44TA, converted into an Otto cycle engine to run on natural gas, also identifying the limiting factors of power in these types of engines. Giving the importance of the compression rate on the Diesel to Otto cycle conversion, the evaluation of the Perkins processed engine happened under the influence of three different rates: 7.6:1; 8.7:1 and 12.3:1. For each compressed rate, and stoichiometric mixture, the task was to choose the spark advance to guarantee best performances to the engine. All tests were performed with a hydraulic dynamometer. The results showed that, the best combination of those parameters are not sufficient to ensure the highest performance of a diesel converted engine. There was a consubstantial rise in temperature of the exhaust gases and on the turbine walls, due to the increase in the exhaust gases volume, compared to that of the burnt gases withdrawn from the original engine, impairing the efficiency and lifespan of the engine components. It was found, by energetic analysis, the compression ratio of 8.7:1, was the most efficient, among the other two, assuring the engine its best performance. As expected, at the compression rate of 7.6:1 the exhaust gases presented the highest temperatures. At compression ratio of 12.3:1 the gas emissions of the converted engine delivered highest NOx level and the lowest level of unburned hydrocarbons at the exhaust. Keywords: Diesel Turbocharged Engine. Diesel to Otto Cycle Conversion Process. Natural Gas. Performance. Energy Balance
Um grande número de empresas nacionais faz uso de grupos geradores a diesel como opção à eletricidade fornecida pela concessionária local. O emprego de grupos geradores é comum durante as horas de pico, que no Brasil, ocorrem entre as 17 e 22 h. Tais aparatos, juntamente com os motores veiculares a diesel têm contribuído para o grande aumento da poluição ambiental, uma vez que a queima deste combustível se faz com grande emissão de particulados, de NOx e de SOx. O gás natural é considerado uma alternativa ao uso do diesel por possuir um alto poder calorífico, queima limpa, e adequada octanagem para o ciclo Otto. O presente trabalho trata da análise de desempenho de um motor Perkins turboalimentado, a diesel, modelo 1104C-44TA, convertido para funcionar apenas com gás natural, identificando ainda, os fatores limitadores de potência nestes tipos de motores. Considerando a importância da taxa de compressão no processo de ottolização, o motor convertido foi avaliado sob a influência de três diferentes taxas: 7,6:1; 8,7:1 e 12,3:1. Para tanto, foram selecionados avanços de ignição que ao interagir com a mistura próxima da estequiométrica garantisse ao funcionamento do motor as melhores condições de desempenho, para cada taxa de compressão escolhida. Os ensaios foram feitos com o auxílio de um dinamômetro hidráulico e os resultados obtidos evidenciaram que, na prática, tais parâmetros não são suficientes para se assegurar os melhores desempenhos em um motor diesel ottolizado. Foi observado um aumento consubstancial na temperatura dos gases de exaustão e na turbina, em virtude da ampliação do volume dos gases de escapamento com relação àquele observado no motor original, com prejuízos para a eficiência e a própria vida útil do motor. Verificou-se, através das análises energéticas, que a taxa de compressão de 8,7:1 permitiu ao motor seu melhor desempenho, com relação à outras experimentadas. Como esperado, o motor operando na taxa de 7,6:1 produziu as mais elevadas temperaturas dos gases de exaustão. Com respeito às emissões gasosas, o motor convertido com taxa de compressão de 12,3:1 emitiu o maior nível de NOx e o menor nível de hidrocarbonetos não queimados
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Muraro, Wilson. "Avaliação do funcionamento de motor ice com gas de baixo poder calorifico proveniente da gaseificação de casca de arroz." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264119.
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Orientador: Caio Glauco SanchezDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica.
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Resumo: Hoje no mundo há uma grande rejeição de matériais, resíduos e outros compostos orgânicos que podem ser aproveitados como fontes de energia. Exemplos podem ser observados em todo o mundo e principalmente em regiões onde a pobreza impera e que a energia elétrica pode ser de grande ajuda ou mesmo como um salva vidas. O emprego de pequenas centrais de geração de potencia integradas a um gaseificador comum motor de combustão interna (Integrated Gasefication Combustion EngineI GCE) do ciclo OTTO e adaptado para operar com gás de baixo poder calorífico, constitui uma alternativa interessante e economicamente viável,que possibilita a produção independente de energia elétrica e térmica (Marcelo,2004). Para o aproveitamento de resíduos de BIOMASSA,como a casca de arroz, utilizou-se um processo de gaseificação,que é uma técnica que possibilita o uso energético da biomassa através da obtenção de um gás de baixo poder calorífico (4a6 MJ/Nm33). Utilizou-se um gaseificador de leito fluidizado do Laboratório de combustão da FEM,onde foi instalado um motor de 5965 litros de cilindrada total e 6 cilindros, com taxa de compressão 12:1, do ciclo OTTO, que originalmente é utilizado em veículos movidos a gás natural comprimido. Obteve se os seguintes valores nos ensaios: Potência (kW)=40.7@ 1800 rpm, Avanço(Graus do virabrequim )=30;Temperatura de Escapamento (°C) =596; Lambda =1,12; Pressão Máxima de Combustão (PA) =4000000. Como funcionamento do motor, verificou se a necessidade de algumas alterações em seus componentes, como também mudanças nas regulagens de avanço. É necessário um sistema para aumentar a pressão do gás proveniente do gaseificador e um sistema de partida inicial. Dessa maneira teríamos um motor para operar como grupo gerador e fazer parte de uma planta piloto para geração de energia elétrica por gaseificação de biomassa
Abstract: Nowadays there is a great waste of organic matters, residues and other substances that could be used in a power plant. Examples can mainly be observed in the whole world and in regions where the poverty reigns and where the electric energy could be of great aid.The use of small power generation plants integrated to a gasification with an internal combustion engine (Integrated Gasification Combustion Engine-GCE) of cycle OTTO and adapted to operate with low power heat rate gas, consists an interesting and economical viable alternative, that makes possible the independent production of electric and thermal energy. For the exploitation of residues of BIOMASS, as the rice husk, we used a gasification process that is a form to increase the energy use of the biomass. The gasification can generate thermal energy and electric energy. It was used gasifier of fluidized bed from UNICAMP, where it was installed an engine with of 5,965 liters and 6 cylinders, with compression rate 12:1(cycle OTTO),which was originally used in vehicles powered by compressed natural gas, to running with the gas of low power heat rate (46 MJ/Nm3) produced by gasifier. Typical experimental result. Power (kW)=40,7@1800rpm; Advance (Degrees)=30; Exhaust gas temperature(°C)=596; Lambda=1,12; Maximum Combustion Pressure (PA)=4000000. During the running of the engine, the necessity of some alterations in some components was verified as well changes in the advance regulations. A system to increase the pressure of the gas proceeding from the gasifier and a system of start are necessary. In this way we would have an engine to operate as generating group and to be part of a pilot plant for generation of eletric energy for gasification of biomass in agricultural and interior cities
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica
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Herring, Jennifer M. "Cranktrain modeling and analysis of connection rod vibrational effects on the overall performance of Otto cycle engines." Thesis, Wichita State University, 2014. http://hdl.handle.net/10057/10961.
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Since connecting rods are a major component in the smooth and efficient running of an engine, how they affect the overall performance is important. The durability of connecting rods in repeated and cyclic operations is significant to the health and performance of an engine. The purpose of this research is to determine what effects the vibrations of connecting rods have on the overall performance of Otto cycle engines. Some studies have been conducted on the static vibration of connecting rods as well as connecting rods in dynamic systems, but those studies only considered the connecting rod design.
Modeling, dynamic analysis, and vibrational analysis are conducted using two different software programs, MSC Adams/View and FEV Virtual Engine. Two different engine configurations are modeled: inline and vee; the results from the two programs are then compared. The data is also checked against vibrational analysis from literature sources as well as having the general performance of the pistons cross-checked against real engine data. The MSC Adams/ View models are composed of simplified cranktrains and forces; while those of FEV Virtual Engine are modeled after actual dimensions and workings. It is determined that the vibrations of connecting rods, under typical operating conditions and material/geometrical properties, do not greatly affect the overall performance of an engine.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
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VILLELA, ANTONIO CARLOS SCARDINI. "COMBUSTION, EFFICIENCY AND PERFORMANCE COMPUTATIONAL MODELING FOR OTTO CYCLE ENGINES AND VEHICLES FOCUSED ON FUEL COMPOSITION AND PROPERTIES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=32577@1.
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Os modelos computacionais comerciais atualmente disponíveis, em geral, não são satisfatoriamente sensíveis a variações na composição e nas propriedades dos combustíveis, não sendo capazes de predizer os seus efeitos no desempenho dos motores e veículos com precisão. Dessa forma, o desenvolvimento de combustíveis é fortemente dependente de experimentos em motores e veículos, demandando significativos custos e prazos de execução. A motivação do presente desenvolvimento reside em fornecer contribuições inéditas para a modelagem computacional de motores e veículos. O foco do trabalho está nos efeitos da composição e das propriedades dos combustíveis sobre os parâmetros de combustão, eficiência e desempenho, buscando a otimização do processo de desenvolvimento de combustíveis. Foi estabelecida metodologia para a modelagem computacional das curvas de pressão no interior do cilindro de um motor do ciclo Otto. Os valores de torque, pressão máxima e ângulo de pressão máxima, obtidos a partir das curvas de pressão simuladas apresentaram, em geral, variações percentuais de até 3 por cento, 5 por cento e 2 graus, respectivamente, em relação aos experimentos. Foi desenvolvida metodologia para a modelagem computacional da autonomia urbana em veículos leves do ciclo Otto, com resultados simulados situados dentro da faixa de incerteza do experimento, de 1,5 por cento. Foram estabelecidas metodologias para modelagem computacional dos tempos de retomada de velocidade e de parâmetros de desempenho de veículos em condições de velocidade constante. A maioria dos resultados simulados se enquadrou na faixa de 3 por cento de diferença em relação aos experimentos.In general, engine s and vehicle s simulation softwares currently available in the market, are not satisfactorily sensitive to composition and fuel properties variations, being unable to accurately predict effects on overall performance. Thus, fuel development process is strongly dependent on engines and vehicles experiments, requiring high costs and long times. This work aims to provide inedited contributions to engines and vehicles computational modeling, focusing on fuel composition and properties on its combustion parameters, efficiency and performance, as well as, to optimize fuel development process. It was established a methodology for an Otto cycle engine in cylinder pressure curves simulation. Torque, maximum pressure and maximum pressure crank angle obtained from the simulated pressure curves presented, in general, percentage changes up to 3 percent, 5percent and 2 degrees, respectively, compared to experiments. It was developed a methodology for Otto cycle light-duty vehicles urban autonomy, with simulated results within the experimental uncertainty range, of 1.5 percent. Methods for speed recovery times and vehicle performance parameters at constant speed simulations were developed. Most simulated results were within the range of 3 percent difference compared to experiments.
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Santos, Pedro Joaquim Pereira dos. "Desenvolvimento de um Range Extender baseado num motor BMW K75 : transformação de ciclo Otto para ciclo Miller." Master's thesis, 2013. http://hdl.handle.net/1822/28224.
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Dissertação de mestrado integrado em Engenharia MecânicaOs 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.
Book chapters on the topic "Otto-cycle engine"
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"Why Gasoline-Fueled Otto-Cycle Engines Would Not Do." In Prime Movers of Globalization. The MIT Press, 2010. http://dx.doi.org/10.7551/mitpress/8572.003.0002.
Full textConference papers on the topic "Otto-cycle engine"
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Cullen, Barry, and Jim McGovern. "Proposed Otto Cycle/Stirling Cycle Hybrid Engine Based Power Generation System." In ASME 2008 Power Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/power2008-60039.
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The generation of electrical and thermal power is a matter of critical importance to the modern world. Considerable quantities of both power types are required in all sectors of society; industrial, domestic and leisure, with the future prosperity of both developed and developing societies being dependant on generation of both a sufficient quantity and quality of power. Central to this discussion on the international front is the topic of fossil fuel usage. Despite considerable advances in renewable energy conversion technologies, the human race remains dependant on fossil fuels as a primary energy source. With increasing demand for these finite resources giving rise to strained international relations and economic uncertainty, emphasis has fallen on optimization of usage patterns. The area of power plant efficiency is essential to this optimization. This paper proposes a method for increasing the efficiency of an Otto cycle engine based plant as is typically used in CHP and other Distributed Generation scenarios. The method proposed is to utilise a Stirling cycle engine as a heat recovery device on the exhaust stream of the Otto engine. Thermal energy that may otherwise be lost would thereby be recovered and used to generate additional electrical power. In this manner energy is effectively diverted from the exhaust flow of the engine and converted to mechanical work by way of the Stirling cycle engine. It is postulated that this combined cycle will yield higher plant efficiency than the Otto engine alone. This paper introduces work completed to date and an experimental plan for the project. The project was initiated at undergraduate level as a feasibility study for application of the hybrid engine in automotive circumstances. The study suggested that the combination of the engines in the proposed manner was indeed feasible, with significant power gains possible. However, it proved unlikely that automotive application was the best use of the system unless certain constraints were addressed. Therefore, it was decided to pursue the concept in terms of a stationary generation system. The advantages of the stationary system over the automotive system are addressed briefly, with the constraints of the automotive scenario analysed and their relevance to the stationary generation situation examined. The central areas under investigation are detailed, including thermodynamic theory pertaining to the Otto cycle and Stirling cycle engines, and the combined cycles. Possible limiting factors to the design are discussed also.
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Feng, Renhua, Yangtao Li, Jing Yang, Jianqin FU, Daming Zhang, and Guangze Zheng. "Investigations of Atkinson Cycle Converted from Conventional Otto Cycle Gasoline Engine." In SAE 2016 World Congress and Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2016. http://dx.doi.org/10.4271/2016-01-0680.
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Britto, Roberto F., Eugênio P. D. Coelho, Sammi Frederico, Marcelo Machado, Daniel Martinek, Celso Rabello, and Thaisa Tomita. "Development of Heavy Duty Otto Cycle Engine Powered by Ethanol." In 22nd SAE Brasil International Congress and Display. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2013. http://dx.doi.org/10.4271/2013-36-0324.
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Ribeiro, Bernardo, Jorge Martins, and Nikit Kothari. "Otto and VCR Miller Engine Performance during the European Driving Cycle." In SAE 2006 World Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2006. http://dx.doi.org/10.4271/2006-01-0440.
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Shkolnik, Nikolay, and Alexander C. Shkolnik. "High Efficiency Hybrid Cycle Engine." In ASME 2006 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/icef2005-1221.
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A “High Efficiency Hybrid Cycle” (HEHC) thermodynamic cycle is explored. This four-stroke cycle borrows elements from Otto, Diesel, Atkinson, and Rankine cycles. Air is compressed into an isolated combustion chamber, allowing for true isochoric combustion, and extended duration for combustion to proceed until completion. Combustion products expand into a chamber with greater volume than intake. We provide details of a compact HEHC design implementation using rotary pistons and isolated rotating combustion chambers. Two Pistons simultaneously rotate and reciprocate and are held in position by two roller bearings. One Piston performs intake and compression, while the other performs exhaust and expansion. We predict a reduction of energy losses, moving part counts, weight and size over conventional engines.
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Boggs, D. L., H. S. Hilbert, and M. M. Schechter. "The Otto-Atkinson Cycle Engine-Fuel Economy and Emissions Results and Hardware Design." In International Congress & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1995. http://dx.doi.org/10.4271/950089.
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Saunders, R. J., and E. A. Abdul-Wahab. "Variable Valve Closure Timing for Load Control and the Otto Atkinson Cycle Engine." In SAE International Congress and Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1989. http://dx.doi.org/10.4271/890677.
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Emerick, Guilherme A., Daniel Z. Carmago, Jordan D. Cussuol, Matheus A. Limas, Alan P. S. Siqueira, Lucas H. P. Deoclecio, and Filipe A. F. Monhol. "Factorial Analysis of Otto Cycle Engine Operating Parameters on the Exhaust Gases Temperature." In 2019 SAE Brasil Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2020. http://dx.doi.org/10.4271/2019-36-0205.
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Benedet Hoffmann, Samuel, and Carlos Roberto Altafini. "ANALYSIS OF VEHICLE POWERED BY SUPERCHARGED VERSUS ASPIRATED OTTO CYCLE INTERNAL COMBUSTION ENGINE." In 18th Brazilian Congress of Thermal Sciences and Engineering. ABCM, 2020. http://dx.doi.org/10.26678/abcm.encit2020.cit20-0030.
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Robinson, Matthew C., and Nigel N. Clark. "Fundamental Explorations of Spring-Varied, Free Piston Linear Engine Devices." In ASME 2014 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icef2014-5432.
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The conventional crank-based internal combustion engine faces many challenges to remain a viable option for electric power generation. Limitations in mechanical, thermal, and combustion efficiencies must be overcome by innovations in existing technologies and progress towards new ones. The free piston linear engine (FPLE) is a device with the potential to meet these challenges. Friction losses are reduced by avoiding rotational motion and linkages. Instead, electrical power is generated by the oscillation of the translator through a stator. Meanwhile, naturally variable compression ratio provides a unique platform to employ advanced combustion regimes. Possibly high variations in stroke length also result in unknown dead center piston positions and greater difficulties in compression control as compared to conventional engines. Without control, adverse occurrences such as misfire, stall, over-fueling, and rapid load changes pose greater complications for stable system operation. Based on previous research, it is believed that incorporating springs will advance former designs by both increasing system frequency and providing a restoring force to improve cycle-to-cycle stability. Despite growing interest in the FPLE, current literature does not address the use of springs within a dual, opposed piston design. This investigation is an extension of recent efforts in the fundamental analysis of such a device. Previous work by the authors combined the dynamics of a damped, spring mass system with in-cylinder thermodynamic expressions to produce a closed-form non-dimensional model. Simulations of this model were used to describe ideal Otto cycle as the equilibrium operating point. The present work demonstrates more realistic modelling of the device in three distinct areas. In the previous model, the work term was a constant coefficient over the length of the stroke, instantaneous heat addition (representing combustion) was only seen at top dead center positions, and the use of the Otto cycle included no mechanism for heat transfer except at dead center positions. Instead, a position based sinusoid is employed for the work coefficient causing changes to the velocity and acceleration profiles. Instantaneous heat addition prior to top dead center is allowed causing the compression ratio to decrease towards stable, Otto operation. And, a simple heat transfer scheme is used to permit cylinder gas heat exchange throughout the stroke resulting in deviation from Otto operation. Regardless, simulations show that natural system stability arises under the right conditions. Highest efficiencies are achieved at a high compression ratio with minimal heat transfer and near-TDC combustion.