Myung Yoon Kim

Characteristics of Particulate Emissions of Compression Ignition Engine Fueled With Biodiesel Derived From Soybean

An experimental investigation was performed on the effect of engine speed and EGR (exhaust gas recirculation) on the particle size distribution and exhaust gas emissions in a compression ignition engine fueled with biodiesel derived from soybean. The results obtained by biodiesel fuel were compared to those obtained by petroleum diesel fuel with sulfur contents of 16.3 ppm. The scanning mobility particle sizer (SMPS) was used for size distribution analysis and it measured mobility equivalent particle diameter in the range of 10.4 to 392.4 nm. In addition to the size distribution of the particles, exhaust emissions such as oxides of nitrogen (NOx ), hydrocarbon (HC), and carbon monoxide (CO) emissions and combustion characteristics under different engine operating parameters were investigated. The engine operating parameters in terms of engine speed, EGR, injection pressure, and intake pressure were varied to investigate the individual impact of the operating parameters. As the engine speed was increased for the both fuels, the larger size particles which dominantly contributes particle mass was increased, however total numbers of particle were reduced. Comparing to petroleum diesel fuel, the combustion of biodiesel fuel in the engine reduced particle concentration of relatively larger size where most of the particle mass is found. Moreover, dramatically lower hydrocarbon and carbon monoxide emissions were found at the biodiesel fueled engine. However, the NOx emission of biodiesel fueled diesel engine shows slightly higher concentration compared to diesel fuel at the same injection timing.Copyright

COMBUSTION AND EMISSION CHARACTERISTICS OF A PARTIAL HOMOGENEOUS CHARGE COMPRESSION IGNITION ENGINE WHEN USING TWO-STAGE INJECTION

The focus of this study was an investigation for the realization of a partial homogeneous charge compression ignition (HCCI) combustion as a control mechanism for HCCI combustion. Premixed fuel was supplied using an in-cylinder early direct injection, and the second injection was made near the TDC to control the ignition and combustion rates of the premixed fuel. In order to obtain the optimal injection timing for the premixed fuel, combustion, and emission characteristics with respect to DI fuel injection timing was investigated in various operational ranges, from conventional diesel combustion to HCCI combustion. The results showed that two-stage injection was very effective in reducing NOx emissions from a DI diesel engine. Additionally, at an optimized injection timing, the ignition of premixed fuel can be controlled by the main injection without premature autoignition. Based on the experimental results, the effect of the premixed ratio and timings of the first and main injections on the combustion characteristics and exhaust emissions in a direct injection diesel engine were discussed.

COMBUSTION AND EMISSION CHARACTERISTICS OF PARTIAL HOMOGENEOUS CHARGE COMPRESSION IGNITION ENGINE

ABSTRACT To investigate the effect of premixed fuel on the combustion and exhaust emission characteristics in a partial homogeneous charge compression ignition (HCCI) engine, an experimental study was performed. The premixed fuels are supplied by the additional fuel injection system in the intake manifold of a direct-injection diesel engine and the injection nozzle for directly injected fuel is equipped in the center of the combustion chamber. The results show that, in the case of gasoline as a premixed fuel, single-stage ignition is found, but premixing the diesel fuel is accompanied by a cool flame prior to the combustion of the directly injected diesel fuel. NOx emissions in the partial HCCI engine with premixed gasoline fuel decrease linearly with increase in premixed ratio. But, for diesel premixed fuel, NOx emission increases at high intake temperature and high premixed ratio conditions.

Reduction of Nitric Oxides and Soot by Premixed Fuel in Partial HCCI Engine

In order to obtain the reduction effect of NO x and soot emission in a partial homogeneous charge compression ignition engine, premixed fuel was supplied with direct injection diesel fuel. Several additional systems such as a premixed fuel injection system, exhaust gas recirculation (EGR) system, supercharger, and air heating system were equipped in the intake manifold of conventional diesel engine. Premixed fuel with air was compressed and ignited by the directly injected diesel fuel in the combustion chamber at the end of compression stroke. The effect of premixed fuel on combustion and emission characteristics of HCCI diesel engine was investigated experimentally under various conditions of intake air temperature, pressure, and EGR rate. The results showed that in case of the use of gasoline as a premixed fuel, single stage ignition is found, but premixing the diesel fuel accompanies the cool flame prior to the combustion of the directly injected diesel fuel. For the gasoline premixed fuel, both NO x and soot can be reduced by the increase of premixed ratio simultaneously. However, for the diesel premixed fuel, the increase of premixed ratio does not have a significant effect in reducing the soot emission.

Experimental Investigation of HCCI Combustion With Reduced Compression Ratio and Narrow Include Angle Injector in a Small DI Diesel Engine

An experimental investigation was performed on a small direct injection (DI) diesel engine equipped with a common-rail injection system to reduce exhaust emissions through HCCI (homogenous charge compression ignition) combustion. Recently, strict environmental standard requirements call for both lower fuel consumption and reduced emissions that could not be achieved by conventional diesel combustion. In this work experimental investigations to achieve simultaneous reduction of NOx and soot by combustion of more diluted fuel/air mixture before the start of ignition were carried out. To realize this fundamental concept, the experimental conditions including injection timing and EGR rate are varied with the different engine configurations. For reducing the deposition of early injected fuel, spray angle of injector is reduced to 60° and piston head shape also modified to fit with the new injector and to reduce the compression ratio to 15:1 for expanding the ignition delay to form diluted mixture before the ignition. Experimental results show that reduced spray angle with modified piston head allow very low NOx and soot emission level while maintaining the high IMEP of diesel combustion.Copyright