• Journal of Advanced Marine Engineering and Technology
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• 제32권4호
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• pp.506-513
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• 2008

The engine containing a radical injector has been studied to improve the performances of efficiency and to reduce the exhaust emissions recently. The engine is far different from general compression ignition engines or spark ignition engines for the concept of combustion process. The inflow characteristic from main chamber into radical chamber during compression stroke is important because the radical chamber must have enough fresh air to generate appropriate radicals. The numerical simulation is performed in each specific shape and the engine speed by using KIVA code. The result shows that the fresh air inflow from main chamber into the radical chamber is the best at 45 degree of the hole angle.

• 동력기계공학회지
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• 제21권1호
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• pp.63-69
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• 2017

The combustion characteristics of gasoline and diesel were tested in a compression ignition engine. Both fuels were used with same common rail injection system. Combustion experiment showed that low load condition of 0.45 MPa IMEP (indicated mean effective pressure) was tested in metal and optical engines. The gasoline combustion showed higher hydrocarbon and carbon monoxide emissions but lower soot emission compared with diesel combustion. NOx emissions were very high at late injection timing but significantly decreased at early injection timing due to the lean combustion resulted from vigorous mixing process. Direct combustion visualization showed that the diesel combustion was dominated by diffusion combustion exhibiting soot incandescence and the gasoline combustion was mostly consisted of premixed combustion showing blue chemiluminescence.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.187-192
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• 2001

A homogeneous premixed charge compression ignition engine is experimentally investigated for the reduction of exhaust emissions in diesel engines. In this study, the premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber and then this pre-mixture is ignited by small amount of diesel fuel directly injected into the cylinder. In the premixed charge compression ignition engine, NOx and smoke concentration of the exhaust emissions were reduced simultaneously as compared with the conventional diesel engine. But HC and CO emissions were increased with the increase of premixed ratio. The combustion characteristics of premixed charged diesel engine such as the power output, the rate of heat release, and the other characteristics are discussed.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2011년도 전기공동학술대회 논문집
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• pp.17-18
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• 2011

• 한국자동차공학회논문집
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• 제20권2호
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• pp.110-115
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• 2012

This study describes the characteristics of combustion and exhaust emission in the special engine applying a fuel reactivity controlled compression ignition (RCCI) concept with two different energizing type (solenoid and piezoelectric) injectors for diesel injection. A diesel-gasoline mixed dual-fuel reactivity controlled compression ignition concept is demonstrated as a promising method to achieve high thermal efficiency and low emission in internal combustion engines for transportation vehicles. For investigating the combustion characteristics of RCCI, engine experiments were performed in a light-duty diesel engine over a range of injection timing and mixing rate of gasoline in mass. It was investigated that by increasing the nozzle hole diameter, increasing the combustion pressure and the net indicated mean effective pressure. $NO_x$ and soot can be reduced by advancing start of injection in 84 mixing rate of gasoline in mass. The resulting operation showed that light duty engine could achieve 48 percent net indicated efficiency and 191[g/kW-hr] net indicated specific fuel consumption with lower levels of nitrogen oxides and soot.

• 한국분무공학회지
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• 제21권3호
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• pp.144-154
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• 2016

This review will be concentrated on the spray characteristics of biobutanol and its blends fuels in internal combustion engines including compression ignition, spark ignition and gas turbine engines. Butanol can be produced by fermentation from sucrose-containing feedstocks, starchy materials and lignocellulosic biomass. Among four isomers of butanol, n-butanol and iso-butanol has been used in CI and SI engines. This is due to higher octane rating and lower water solubility of both butanol compared with other isomers. The researches on the spray characteristics of neat butanol can be classified into the application to CI and SI engines, particularly GDI engine. Two empirical correlations for the prediction of spray angle for butanol as a function of Reynolds number was newly suggested. However, the applicability for the suggested empirical correlation is not yet proved. The butanol blended fuels used for the investigation of spray characteristics includes butanol-biodiesel blend, butanol-gasoline blend, butano-jet A blend and butanol-other fuel blends. Three blends such as butanol/ethanol, butanol/heptane and butanol/heavy fuel oil blends are included in butanol-other fuel blends. Even though combustion and emission characteristics of butanol/diesel fuel blend in CI engines were broadly investigated, study on spray characteristics of butanol/diesel fuel blend could not be found in the literature. In addition, the more study on the spray characteristics of butanol /gasoline blend is required.

• 한국자동차공학회논문집
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• 제16권3호
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• pp.80-86
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• 2008

Recently, controlled auto ignition(CAI) in gasoline engines are drawing more attentions due to its extremely low level of NOx emissions and potentials in lowering the fuel consumption rate. The one of the key techniques for realizing CAI combustion in engines is the control of valve system. Since the valve linkage system with higher complexity, or even earn-less valve systems, such as electro-hydraulic and electro-magnetic system, are adopted in CAI engines, it is not easy to estimate the valve lift profile from earn profiles. Therefore new measurement techniques for valve lift in CAI engines have been tried and tested. In this paper, hole type valve lift sensor was developed and tested to check the applicability in CAI engines. The valve lifts could be obtained from the sensor signal, which depends on the distance from the sensor to magnet attached to valve. Various engine speeds, ranging from 2,000 to 6,000 rpm, and valve lifts, maximum up to 9.7 mm, were tested. It was found that the sensor output for valve lift had accuracy of 98% in comparison with the basic specifications of valve lift through improvements of sensor driving circuit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.966-969
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• 1998

Fast burning achieves higher efficiency, and reduces cycle variations which is able to improve vehicle driveability. Furthermore, the greater resistance to knock with fast burning can allow the fuel economy advantages associated with higher compression ratio to be realized. One way of increasing the combustion speed is to enhance the performance of ignition systems which were able to reduce the early period of combustion. It is well known that shortening the initial stage of combustion also reduces the cyclic variations. This literature survey deals with the papers which have studied the ignition process or various ignition systems. Those systems increasing the combustion speed, extending the lean misfire limit, reducing the exhaust gas and stabilizing the operating condition of the spark ignition engine by modifying the ignition process or increasing ignition energy.

• International Journal of Automotive Technology
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• 제8권2호
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• pp.137-147
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• 2007

Homogenous Charge Compression Ignition (HCCI) combustion systems can be broadly divided for the process applied to 4-stroke and 2-stroke engines. The former process is often referred to as simply HCCI combustion and the latter process as Active Thermo-Atmosphere Combustion (ATAC). The region of stable engine operation tends to differ greatly between the two processes. In this study, it was shown that the HCCI combustion process of a 4-stroke engine, characterized by the occurrence of autoignition under a high compression ratio, a lean mixture and wide open throttle operation, could be simulated by operating a 2-stroke engine at a higher compression ratio. On that basis, a comparison was made of the combustion characteristics of high-compression-ratio HCCI combustion and ATAC, characterized as autoignited combustion in the presence of a large quantity of residual gas at a low compression ratio and part throttle. The results showed that one major difference between these two combustion processes was their different degrees of susceptibility to the occurrence of cool flame reactions. Compared with high-compression-ratio HCCI combustion, the ignition timing of ATAC tended not to change in relation to different fuel octane numbers. Furthermore, when internal EGR was applied to high-compression-ratio HCCI combustion, it resulted in combustion characteristics resembling ATAC. Specifically, as the internal EGR rate was increased, the ignition timing showed less change in relation to changes in the octane number and the region of stable engine operation also approached that of ATAC.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.76-83
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• 2002

Mathematically and chemically simplified reaction scheme for n(heptane that simulates autoignitions of the end gases in spark ignition engines has been developed and studied computationally. The five(equation model is described, to predict the essential features of hydrocarbon oxidation. This scheme has been calibrated against autoignition delay times measured in rapid compression machines. The rate constants, activation temperatures, Ta, Arrhenius pre-exponential constants, A, and heats of reaction for stoichiometric nheptane/air has all been optimized. Comparisons between computed and experimental autoignition delay times have validated the present simplified reaction scheme. The influences of heat loss and concentration of chain carrier at the beginning of compression upon autoignition delay times have been computationally investigated.