On-board hydrogen and syngas production is considered as a transition solution from fossil fuel to hydrogen powered vehicles until problems associated with hydrogen infrastructure, distribution and storage are resolved. A hydrogen- or syngas-rich stream, which substitutes part of the main hydrocarbon fuel, can be produced by supplying diesel fuel in a fuel-reforming reactor, integrated within the exhaust pipe of a diesel engine. The primary aim of this project was to investigate the effects of intake air enrichment with product gas on the performance, combustion and emissions of a diesel engine. The novelty of this study was the utilisation of the dilution effect of the reformate, combined with replacement of part of the hydrocarbon fuel in the engine cylinder by either hydrogen or syngas. The experiments were performed using a fully instrumented, prototype 2.0 litre Ford HSDI diesel engine. The engine was tested in four different operating conditions, representative for light- and medium-duty diesel engines. The product gas was simulated by bottled gases, the composition of which resembled that of typical diesel reformer product gas. In each operating condition, the percentage of the bottled gases and the start of diesel injection were varied in order to find the optimum operating points. The results showed that when the intake air was enriched with hydrogen, smoke and CO emissions decreased at the expense of NOx. Supply of nitrogen-rich combustion air into the engine resulted in a reduction in NOx emissions; nevertheless, this technique had a detrimental effect on smoke and CO emissions. Under low-speed low-load operation, enrichment of the intake air with a mixture of hydrogen and nitrogen led to simultaneous reductions in NOx, smoke and CO emissions. Introduction of a mixture of syngas and nitrogen into the engine resulted in simultaneous reductions in NOx and smoke emissions over a wide range of the engine operating window. Admission of bottled gases into the engine had a negative impact on brake thermal efficiency. Although there are many papers in the literature dealing with the effects of intake air enrichment with separate hydrogen, syngas and nitrogen, no studies were found examining how a mixture composed of hydrogen and nitrogen or syngas and nitrogen would affect a diesel engine. Apart from making a significant contribution to existing knowledge, it is 3 believed that this research work will benefit the development of an engine-reformer system since the product gas is mainly composed of either a mixture of hydrogen and nitrogen or a mixture of syngas and nitrogen.

This thesis is about modelling of the combustion and emissions of dual fuel HCCI engines for design of “engine combustion system”. For modelling the combustion first the laminar flamelet model and a hybrid Lagrangian / Eulerian method are developed and implemented to provide a framework for incorporating detailed chemical kinetics. This model can be applied to an engine for the validation of the chemical kinetic mechanism. The chemical kinetics, reaction rates and their equations lead to a certain formula for which the coefficients can be obtained from different sources, such as NASA polynomials [1]. This is followed by study of the simulation results and significant findings. Finally, for investigation of the knock phenomenon some characteristics such as compression ratio, fuel equivalence ratio, spark timing and their effects on the performance of an engine are examined and discussed. The OH radical concentration (which is the main factor for production of knock) is evaluated with regard to adjustment of the above mentioned characteristic parameters. In the second part of this work the specification of the sample engine is given and the results obtained from simulation are compared with experimental results for this sample engine, in order to validate the method applied in AVL Fire software. This method is used to investigate and optimize the effects of parameters such as inlet temperature, fuels ratio, diesel fuel injection timing, engine RPM and EGR on combustion in a dual fuel HCCI engine. For modelling the dual fuel HCCI engine AVL FIRE software is applied to simulate the combustion and study the optimization of a combustion chamber design. The findings for the dual fuel HCCI engine show that the mixture of methane and diesel fuel has a great influence on an engine's power and emissions. Inlet air temperature has also a significant role in the start of combustion so that inlet temperature is a factor in auto-ignition. With an increase of methane fuel, the burning process will be more rapid and oxidation becomes more complete. As a result, the amounts of CO and HC emissions decrease remarkably. With an increase of premixed ratio beyond a certain amount, NOX emissions decrease. With pressure increases markedly and at high RPM, knock phenomenon is observed in HCCI combustion.

[pt] Neste estudo, os esforços são concentrados em se buscar a redução das emissões em motores Diesel-gás. Assim, são apresentados resultados experimentais, obtidos em dinamômetro de bancada, das emissões e desempenho de um motor do ciclo Diesel (turbo alimentado e com intercooler), para operar, reversivelmente, como motor Diesel-gás ou Diesel original. Inicialmente, foram executados ensaios nas duas versões, Diesel e Diesel-gás; logo, os resultados respectivos foram comparados em termos de emissões e desempenho do motor. A seguir, na operação Diesel-gás, foi avaliado o método da restrição parcial do ar de admissão, a fim de produzir uma mistura efetivamente mais rica para a mesma quantidade do gás natural. Os resultados obtidos mostraram uma notável redução nas emissões de monóxido de carbono e hidrocarbonetos não queimados, para toda a faixa de operação avaliada. Por outro lado, as emissões de material particulado continuaram sendo ínfimas em altas taxas de substituição e os níveis de óxidos de nitrogênio apresentaram certo incremento em altas cargas do motor. Quanto ao rendimento térmico, verificam-se acréscimos quando é alcançado certo valor de taxa de substituição. Contudo, os resultados de emissões e rendimento térmico apresentam melhores resultados em baixas cargas do motor (abaixo de 50% da plena carga). Assim, além de reduzirem-se os níveis de certas emissões em altas cargas, verificou-se uma contribuição adicional do presente trabalho no que diz respeito à redução, de forma parcial, de um dos principais problemas envolvendo a combustão em motores Diesel-gás: a queima incompleta de misturas pobres em cargas baixas. / [en] The focus of this study is the reduction of emissions in Gas-Diesel engines. The experimental results of emissions and performance of a Diesel cycle engine (with turbo and intercooler), obtained by a dynamometer, are presented for operation as Gas-Diesel and as original Diesel engine. First, two kinds of operation were tested: Diesel and Gas-Diesel; then, the respective results of emissions and performance of the motor were compared. After, in Gas-Diesel operation, was evaluated the method of the partial restriction of the admission air, to produce a richer mixture with the same quantity of natural gas used before. The obtained results show a notable reduction of the emissions of carbon monoxide and unburned hydrocarbons for the whole range of evaluated operation. On the other hand, the particulate emissions had kept minims at high rates of substitution and the nitrogen oxides levels presented a bit of increase at high engine load. The thermal performance increases when is achieved a determinate substitution rate value. However, the emissions and thermal performance results have a better behavior at low engine loads (below 50% of the full load). Thus, beyond the levels of some emissions are reduced at high loads, in addition, a reduction was found, of partial form, from one of the main problems involving combustion in Gas-Diesel engines: the incomplete burning of poor mixtures in low loads.

A new quasi-dimensional, multi-zone model has been developed to describe the combustion processes occurring inside a dual fuel engine. A dual fuel engine is a compression ignition engine in which a homogeneous lean premixed charge of gaseous fuel and air is ignited by a pilot fuel spray. The atomisation and preparation of the pilot leads to the formation of multiple ignition centres from which turbulent flame fronts develop. The energy release in a dual fuel engine is therefore a combination of that from the combustion of the pilot fuel spray and lean premixed charge. Hence, the dual fuel combustion process is complex, combining elements of both conventional spark and compression ignition engines. The dual fuel engine is beneficial as it can achieve significant reductions in emissions of carbon dioxide (CO2), as well as reducing emissions of oxides of nitrogen (NOx) and particulate matter (PM).

Submitted by Maicon Juliano Schmidt (maicons) on 2015-05-07T16:35:35Z No. of bitstreams: 1 Josimar Souza Rosa.pdf: 2316699 bytes, checksum: 10b8be8bf5285234719e629c53ebeb82 (MD5) / Made available in DSpace on 2015-05-07T16:35:35Z (GMT). No. of bitstreams: 1 Josimar Souza Rosa.pdf: 2316699 bytes, checksum: 10b8be8bf5285234719e629c53ebeb82 (MD5) Previous issue date: 2014-03-21 / Nenhuma / Este trabalho buscou analisar o funcionamento de um motor de combustão interna (ciclo Diesel) operando com misturas parciais de óleo diesel com gás natural veicular, e óleo de soja com gás natural veicular. Os ensaios foram realizados em um motor Agrale modelo M90, monocilíndrico, acoplado a um alternador, tendo como carga um banco de resistências. A análise realizada contemplou o desempenho em termos de consumo de combustível, potência e emissões gasosas de óxidos de nitrogênio, dióxidos de enxofre, monóxido de carbono, entre outros gases, bem como a análise da opacidade da fumaça. Os resultados mostraram que é viável a utilização de gás natural em motores ciclo Diesel sem remoção do sistema de injeção de diesel original, representando uma considerável redução nas emissões específicas dos óxidos de nitrogênio, sem perda de potência, porém resultando em combustão incompleta em altos percentuais de substituição de combustível líquido por gasoso. De maneira geral o melhor resultado em relação à eficiência foi possível com percentual de substituição de 43,7% de diesel por gás natural, no qual o conjunto motor gerador apresentou rendimento aproximado de 33,17%. A opacidade da fumaça emitida pelo motor foi reduzida significativamente quando funcionou em modo bi-combustível tanto com diesel e gás natural como óleo de soja e gás natural. / This study aims to analyze the operation of an internal combustion engine (diesel cycle) with partial mixtures of diesel oil and natural gas, and oil vegetable soybean and natural gas. The tests were carry in an engine Agrale model M90, monocilynder, coupled to alternator, and which charged a bank of resistors load. The analyses include performance fuel consumption, power and gas emissions of nitrogen oxides, sulfur dioxides, carbon monoxide, and other gases, as well the analysis of the smoke opacity. Results showed that it is feasible to use natural gas in diesel cycle engines without removing the original diesel injection system, generating a considerable reduction in specific emissions of nitrogen oxides, without loss of Power, but resulting in incomplete combustion at high percentages replacement of liquid fuel for natural gas. Generally, the Best result for efficiency was possible with replacement percentage of 43,7% of diesel per natural gas, when the generation setting showed efficiency equal at 33,17%. The smoke opacity was reduced significantly when operated in dual fuel both diesel and natural gas as soybean oil and natural gas.

The aim of this study is to experimentally measure performance characteristics of a compression ignition (CI) internal combustion engine using superheated ethanol vapor. The engine is a 1.3L inline 4 cylinder direct injection (DI) turbocharged compression ignition (CI) engine. While the engine will be fed with superheated ethanol as homogeneous fuel-air mixture through intake manifold, the amount of diesel fuel that the engine requires to run at idle will also be supplied in order to initiate combustion. Ethanol will be superheated using a new patented double heat exchanger has been manufactured by Prof. Dr. Demir Bayka, Dr. Anil Karel and Deniz &Ccedil / akar. The results will indicate if the suggested concept can be applicable.

The continuous update of challenging emission legislations has renewed the interest for the use of alternative fuels. The low carbon content, the knocking resistance, and the abundance reserves, have classified natural gas as one of the most promising alternative fuels. The major constituent of natural gas is methane. Historically, the slow burning velocity of methane has been a major concern for its utilisation in energy efficient combustion applications. As emphasized in a limited body of experimental literature, a binary blend of methane and gasoline has the potential to accelerate the combustion process in an SI engine, resulting in a faster combustion even to that of gasoline. The mechanism of such effects remains unclear. This is partially owned to the inadequate prior scientific understanding of the fundamental combustion parameters, laminar burning velocity (Su0) and Markstein length (Lb), of a gasoline-natural gas Dual Fuel (DF) blend. The value of Lb characterises the sensitivity of the flame to stretch. The flame stretch is induced by aerodynamic straining and/or flame curvature. The current research study has therefore being concerned on understanding the combustion mechanism of premixed gasoline - natural gas DF blends both on a fundamental as well as practical SI engine level. The understanding on the contribution of Su0 and Lb to the velocity of a stretched laminar propagating flame has been extended through numerical analysis. A conceptual analysis of the laminar as compared to the SI engine combustion allowed further insights on the effect of turbulence to the mass burning rate of the base fuels. On a fundamental level, the research contribution is made through the quantification of the response of Su0 and Lb with the ratio of methane to PRF95 (95%volliq iso-octane and 5%volliq n-heptane) in a DF blend. Methane has been used as a surrogate for natural gas and PRF95 as a surrogate for gasoline. Constant volume laminar combustion experiments have been conducted in a cylindrical vessel at equivalence ratios of 0.8, 1, 1.2, initial pressures of 2.5, 5, 10 Bar, and a constant temperature of 373 K. Methane was added to PRF95 in three different energy ratios 25%, 50% and 75%. Spherically expanding flames visualised through schlieren photography were used to derive the values of Lb and Su0. It has been concluded that for pressures relevant to SI engine operation ( > 5bar) and stoichiometric to lean Air Fuel Ratios (AFRs), there is a positive synergy for blending methane to PRF95 due to the convergence of Lb of the blended fuel towards that of pure gas and Su0 towards that of pure liquid. In an SI engine environment, the research contribution is made through the characterisation and scientific understanding of the mechanism of DF combustion, and the importance of flame-stretch interactions at various engine operating conditions. Optical diagnostics have been integrated with in-cylinder pressure analysis to investigate the mechanism of flame velocity and stability with the addition of natural gas to gasoline in a DF blend, under a sweep of engine load (Manifold Absolute Pressure = 0.44, 0.51. 0.61 Bar), speed (1250, 2000, 2750 RPM) and equivalence ratio (0.8, 0.83, 1, 1.25). Consisted with the constant volume experiments, natural gas was added to gasoline in energy ratios of 25%, 50% and 75%. It has been concluded that within the flamelet combustion regime the effect of Lb is dominating the lean burn combustion process both from a flame stability and velocity prospective. The effect of Su0 on the combustion process gradually increases as the AFR shifts from stoichiometric to fuel rich values. For stoichiometric to fuel lean mixtures, the effect of turbulence on the increase of the mass burning rate is on average 13% higher for natural gas as compared to gasoline. The higher turbulence sensitivity of natural gas is attributed to its lower Lb value.

Diesel-ignited gasoline and diesel-ignited methane dual fuel combustion experiments were performed in a single-cylinder research engine (SCRE), outfitted with a common-rail diesel injection system and a stand-alone engine controller. Gasoline was injected in the intake port using a portuel injector, whereas methane was fumigated into the intake manifold. The engine was operated at a constant speed of 1500 rev/min, a constant load of 5.2 bar IMEP, and a constant gasoline/methane energy substitution of 80%. Parameters such as diesel injection timing (SOI), diesel injection pressure, and boost pressure were varied to quantify their impact on engine performance and engineout ISNOx, ISHC, ISCO, and smoke emissions. The change in combustion process from heterogeneous combustion to HCCI like combustion was also observed.

Diesel-ignited methane dual fuel combustion experiments were performed in a single cylinder research engine (SCRE). Methane was fumigated into the intake manifold and injection of diesel was used to initiate combustion. The engine was operated at a constant speed of 1500 rev/min, and diesel rail pressure was maintained at 500 bar. Diesel injection timing (SOI) was varied to quantify its impact on engine performance and engine-out ISNOx, ISHC, ISCO, and smoke emissions. The SOI sweeps were performed at different net indicated mean effective pressures (IMEPs) of 4.1, 6.5, 9.5, and 12.1 bar. Intake manifold pressure was maintained at 1.5 bar for the 4.1 and 6.5 bar IMEP SOI sweeps and 1.8 bar for the 9.5 and 12.1 bar IMEP SOI sweeps. Advancing SOI to 310º and earlier resulted in reduced ISNOx. However, high methane percent energy substitution (PES) resulted in high ISHC emissions especially at low IMEP.

Gold-based catalysts can be replaced with platinum group catalysts in catalytic automotive exhaust aftertreatment if their thermal stability and durability issues can be resolved. Hence, one of the potential markets for gold catalysis is the automotive after treatment market, our interest is to synthesize a gold-based catalyst which has practical applications in automotive industry specifically for diesel-methane dual fuel low-temperature combustion strategy where the exhaust temperature is varying from ~ 200 to400° C. Our research focused on synthesizing a bimetallic gold-copper catalyst which is not only highly active for CO oxidation reaction but also sinter-resistant at temperatures normally observed at LTC engine exhaust. The Au-Cu@SiO2 catalyst exhibited excellent efficacy for CO oxidation with >95% conversion to CO2 achieved at 300 °C. While the presence of Cu enhanced CO conversion at low to intermediate temperatures (50-300 °C), silica encapsulation of the Au-Cu nanocomposites facilitated for remarkable stability of the catalyst. Moreover, the catalyst exhibited remarkable stability at high reaction temperatures which could be attributed to the SiO2 encapsulation of nanoparticles. The activity and stability of Au-Cu@SiO2 catalyst are suitable for its application in automotive after treatment devices, especially in low-temperature combustion engine exhaust.