Wyniki wyszukiwania - BazTech

1

Combustion stability of dual fuel engine powered by diesel-ethanol fuels

Nowak Łukasz, Tutak Wojciech

Combustion Engines

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2019

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R. 58, nr 3

155--161

EN

The paper presents result of combustion stability assessment of dual fuel engine. The authors analyzed results of co-combustion of diesel fuel with alcohol in terms of combustion stability. The comparative analysis of both the operational parameters of the engine and the IMEP, as the parameters determining the stability of the combustion process, were carried out. It was analyzed, among others values of the COVIMEP coefficient, the spread of the maximum pressure value, the angle of the position of maximum pressure and the probability density distribution of the IMEP. The experimental investigation was conducted on 1-cylinder air cooled compression ignition engine. The test engine operated with constant rpm equal to 1500 rpm and constant angle of start of diesel fuel injection. The engine was operated with ethanol up to 50% of its energy fraction. The influence of ethanol on ignition delay time spread and end of combustion process was evaluated. It turns out that the share of ethanol does not adversely affect the stability of ignition.

2

Thermodynamic analysis of combustion events in the natural gas fuelled SI engine with VVT

Szwaja M., Mazuro P., Szwaja S.

Journal of KONES

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2018

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Vol. 25, No. 4

421--427

EN

The main aim of the research was to investigate influence of overlap of the natural gas fuelled spark ignited engine on the following parameters: Indicated Mean Effective Pressure (IMEP), heat rate release including combustion phases (ignition lag, main combustion phase). The content of the study includes results from processing in-cylinder pressure measurements, heat release rate analysis, combustion phases, and finally the conclusions. The tests were carried out on the test bed including the single cylinder research engine with a displacement volume of 550 cm3. The engine was equipped with independent cam phasors for both intake and exhaust valves, but for this investigation, the exhaust valve timing was fixed (the exhaust cam centre line was fixed at -95 crank angle (CA) deg before Top Dead Centre) and intake valve timing was changed (the intake cam centre line was varied from 90 to 150 CA deg after Top Dead Centre). The overlap was changed in the range from 85 to 25 CA deg. 8 tests series were performed, each singular series consisted of 300 consecutive engine combustion cycles. As observed, by varying the valve overlap it contributes to significant change in the peak combustion pressure, peak of heat release rate, and combustion phases. Summing up, variable valve timing affects compression and expansion strokes by changing polytropic indexes due to various amounts of exhaust residuals trapped in the cylinder. It affects not only engine volumetric efficiency but also the heat release rate and IMEP, so it does engine performance. Thus, variable valve timing can be considered as valuable tool that can be applied to the natural gas fuelled internal combustion engine.

3

Cmbustion of mixture of diesel fuel with gasoline in a compression ignition engine

Tutak W., Jamrozik A.

Journal of KONES

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2018

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Vol. 25, No. 2

391--398

EN

Paper presents results of experimental investigation of combustion process of diesel-gasoline blend in compression ignition direct injection engine. The researches were conducted for constant load of engine at constant rotational speed. Operating parameters of engine powered with diesel-gasoline blend were at the same level as for engine powered by pure diesel fuel. The preliminary study was conducted using CFD modelling. Based on encouraging modelling results preliminary experimental research was carried out. It turned out that it is possible to co-burning diesel with the gasoline as a blend. A mixture of 20, 40 and 60% of gasoline with diesel was used. It was concluded that an increase in gasoline fraction in blend causes delay of start of the combustion process. The homogeneity of the fuel-air mixture was improved due to longer ignition delay, which is accompanied by higher values of pressure rise rate. With 20 and 40% of gasoline fraction causes higher peak pressure compared to reference fuel-burning ware obtained. Up to 40% of gasoline fraction, the BSFC was kept at the same level as for reference fuel. It was observed that with the increase in gasoline fraction up to 40% NOx emission increased as well. Based on the carried out tests it can be stated that it is possible to co-burn gasoline with diesel in a compression ignition engine while maintaining the invariable engine operating parameters and exhaust emissions.