• Journal of the Korean Society of Combustion
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• v.16 no.1
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• pp.52-57
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• 2011

The present study describes the characteristics of combustion and exhaust emissions in compression ignition engines using diesel-gasoline dual fuel. For investigating combustion characteristics, diesel fuel was injected directly in a single-cylinder compression ignition engine with a common-rail injection system and gasoline fuel was injected into a premixed chamber installed in an intake port. In order to investigate exhaust emission characteristics, exhaust gas was measured by emission analyzer and smoke meter. The experimental results showed that cases of diesel-gasoline dual fuel combustion exhibited extended ignition delay and reduced peak combustion pressure compared to those of directly injected diesel fuel cases. Furthermore, premixed gasoline-air mixture reduced NOx emissions due to low peak of rate of heat release(ROHR).

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.4
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• pp.26-31
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• 2006

An experimental investigation of an early injection strategy was conducted on a small single cylinder common-rail DI diesel engine to reduce the oxides of nitrogen($NO_x$) emission. The main objectives of this study were to investigate the emissions, performance and combustion characteristics in a diesel engine with early and two-stage injections. The two- stage injection was conducted to reduce the wall-wetting of early injected fuels on the cylinder wall or to promote the ignition of premixed charge. The engine test was performed at conditions of 1500rpm, injection timing ranging from TDC to BTDC $80^{\circ}$. The experimental results show that $NO_x$ emissions were decreased in both cases of early injection and two stage injection compared to the conventional diesel combustion by the near TDC injection. However, soot and products of incomplete products (i.e. HC and CO) are slightly increased. Also, the second injection near TDC promoted the ignition of premixed fuel, therefore, IMEP was increased.

• Environmental Engineering Research
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• v.22 no.3
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• pp.294-301
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• 2017

This paper is based on experiments conducted on a stationary, four stroke, naturally aspirated air cooled, single cylinder compression ignition engine coupled with an electrical swinging field dynamometer. Instead of 100% diesel, 20% Jatropha oil methyl ester with 80% diesel blend was injected directly in engine beside 25% pre-mixed charge of diesel in mixing chamber and with 20% exhaust gas recirculation. The performance and emission characteristics are compared with conventional 100% diesel injection in main chamber. The blend with diesel premixed charge with and without exhaust gas recirculation yields in reduction of oxides of nitrogen and particulate matter. Adverse effects are reduction of brake thermal efficiency, increase of unburnt hydrocarbons (UBHC), carbon monoxide (CO) and specific energy consumption. UBHC and CO emissions are higher with Diesel Premixed Combustion Ignition (DPMCI) mode compared to compression ignition direct injection (CIDI) mode. Percentage increases in UBHC and CO emissions are 27% and 23.86%, respectively compared to CIDI mode. Oxides of nitrogen ($NO_x$) and soot emissions are lower and the percentage decrease with DPMCI mode are 32% and 33.73%, respectively compared to CIDI mode.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.81-89
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• 2009

In this experimental study, the effects of clean alternative fuels compatible with diesel combustion on nano-sized particle emission characteristics were investigated in a 0.5L auto-ignited single-cylinder engine with a compression ratio of 15. Because the number concentration of nano-sized particles emitted by automotive engine, that are suspected of being hazardous to human health and environment, might increase with engine fuel considerably and recently attracted attention. So a ultra-low sulfur diesel(ULSD), BD100(100% bio-diesel) and Di-Methyl Ether(DME) fuels used for this study. And, as a particle measuring instrument, a fast-response particle spectrometer (DMS 500) with heated sample line was used for continuous measurement of the particle size and number distribution in the size range of 5 to 1000nm (aerodynamic diameter). As this research results, we found that this measurements involving the large proportion of particles under size order of 300nm and number concentration of $4{\times}10^9$ allowed a single or bi-modal distribution to be found at different engine load conditions. Also the influence of oxygen content in fuel and the catalyst could be a dominant factor in controlling the nano-sized particle emissions in auto-ignited engine.

• International Journal of Advanced Culture Technology
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• v.4 no.1
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• pp.10-18
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• 2016

In the present study, a single cylinder four stroke dual fuel diesel engine was tested to investigate the performance and emission characteristics of various test fuels. The engine was tested in dual fuel mode using diesel and Karanja biodiesel blends as pilot fuel along with Natural gas as primary fuel with a constant gas flow rate under different loading conditions. From the experimentation it was found that smoke opacity and oxides of nitrogen (NOx) are at low level for all the prepared test fuels in dual fuel mode but the emissions of carbon monoxide (CO), carbon dioxide ($CO_2$) and hydrocarbon (HC) were found higher. In comparison to diesel fuel, by increasing the blend percentage different emission parameters are found to be reduced. At different loading conditions all the test fuels show poor performance in dual fuel mode of operation when compared with single mode of operation with diesel and biodiesel. With increase in gas flow rates, except (NOx) and smoke emissions, the other emission parameters like CO, HC and $CO_2$ values increased for all test fuels. Again, all blended fuels showed lower performance compared to diesel. The maximum pilot fuel savings for diesel was found decreasing with the increase in karanja biodiesel. From the present work it may be concluded that Karanja biodiesel with Natural gas in dual mode can be can used as promising alternative for diesel with some required engine modifications and further research must be carried out to minimize the emissions of CO, HC and $CO_2$.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.1-8
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• 2011

In recent years, there has been an interest in early-injection diesel engines as it has the potential of achieving a more homogeneous and leaner mixture close to TDC compared to standard diesel engine. The more homogeneous mixture may result in reduced NOx and soot emissions and higher efficiency in homogeneous charge compression ignition engines. While earlier studies have shown that a reduction in NOx emissions from HCCI engine is possible, there are some significant problems including the control of ignition timing and combustion rate. In order to investigate the effect of EGR and hydrogen enriched gas on combustion characteristics and emissions, an experiments with single cylinder CRDi engine were carried out concerning the formation of various premixed charge, which can achieved by early injection, EGR and hydrogen enriched gas. EGR was not effective to further reduce NOx and PM emissions. It was found that NOx emissions were decreased with an introduction of hydrogen enriched gas and an adequate diesel fuel amount.

• Journal of the Korean Society of Combustion
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• v.20 no.4
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• pp.26-33
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• 2015

American NREL (National Renewable Energy Laboratory) reported that BD20 could reduce PM, CO, SOx and cancerogenic matters by 13.6%, 9.3%, 17.6% and 13% respectively, compared to diesel fuel. BD20 has been being tested on garbage trucks and official vehicles at Seoul City, which is positive on air environment, but negative on combustion by higher viscosity in winter season. This study investigated the combustion characteristics by employing multi cavity piston for improving the deterioration of combustibility caused by the higher viscosity of the biodiesel fuel such as BD20 with the combustion flames taken by a high speed camera and the cylinder pressure diagram. A 4-cycle single cylinder diesel engine was remodeled to a visible 2-cycle engine for taking the flame photographs, which has a common-rail injection system. The test was done at laboratory temperature of about $4{\sim}5^{\circ}C$.

• Journal of Power System Engineering
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• v.7 no.1
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• pp.14-19
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• 2003

A diesel engine has been widely used for ship and industry power because it has many merits of high thermal efficiency, reliability and durability. However its exhaust gas is harmful to human and air environment. Reducing the hurtful exhaust gas emissions, the study of the gas flow in the inlet and exhaust manifold is in progress in the world. In this paper we modeled the gas flow as one dimensional isentropic flow to predict the gas flow in the exhaust manifold. The method of characteristics was used for the model calculation, and the calculated results were compared with the experimental ones.

• Journal of the Korean Society of Combustion
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• v.17 no.2
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• pp.24-31
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• 2012

Diesel engines exhaust much more NOx(Nitrogen Oxides) and PM(Particulate Matter) than gasoline engines, and it is not easy to reduce both NOx and PM simultaneously because of the trade-off relation between two components. This study investigated flame characteristics of the partial premixed compression ignition known as new combustion method which can reduce NOx and PM simultaneously. The investigation was performed through the analysis of the flame images taken by a high speed camera from the visible engine which is the modified single cylinder diesel engine. The results obtained through this investigation are summarized as follows; (1) The area of the luminous yellow flame was reduced due to the decrease of flame temperature and even distribution of temperature. (2) The darkish yellow flame zone caused by the shortage of the remaining oxygen after the middle stage of combustion was considerably reduced. (3) Since the ignition delay was shortened, the violent combustion did not occur and the combustion duration became shortened.

• Journal of the Korean Society of Combustion
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• v.22 no.1
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• pp.1-7
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• 2017

This paper presents an experimental study on the effect of double injection strategies on combustion characteristics in a single-cylinder diesel engine. These studies are applied to the double injection strategies, such as $2^{nd}$ injection timing variations with fixed injection interval (8 degree) and variations of injection pressures with fixed injection timing and intervals. The injection quantity was 7 + 7 mg for double injections, and 14 mg for single injection. When the injection pressure was increased, the ignition delay was shortened, and the ISFC (indicated specific fuel consumption) was increased due to the fast termination of combustion by the shortened energizing duration. In addition, the retardation of injection timings toward TDC (top dead center) caused the reduction of ignition delay and the decrease of ISFC with the decrease of FMEP (friction mean effective pressure).