• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.37-40
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• 2013

Hydrogen-dimethy ether (DME) and hydrogen-diesel compression ignition engine combustion were investigated and compared each other in a single cylinder compression ignition engine. Hydrogen and DME were used as low carbon alternative fuels to reduce green house gases and pollutant. Hydrogen was injected at the intake manifold with an injection pressure of 0.5 MPa at fixed injection timing, $-210^{\circ}CA$ aTDC. DME and diesel were injected directly into the cylinder through the common-rail injection system at injection pressure of 30 MPa. DME and diesel inejction timing was varied to find the optimum CI combustion to reduce CO, HC and NOx emissions. When DME was injected early, CO and HC emissions were high while NOx emission was low. Fuel consumption, heat release rate, and exhaust emissions were measured to analyze each combustion characteristics of each ignition promoter. Fuel consumption was decreased when diesel was used as an ignition promoter. This is due to the lower volatility of diesel which created more stratified charge than DME.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.61-66
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• 2007

A CRDI diesel engine used to commercial vehicle was fueled with 20% biodiesel fuel(BDF 20) in excess of 150 hours. Engine dynamometer testing was completed at regularly scheduled intervals to monitor the engine performance and exhaust emissions. The engine performance and exhaust emissions were sampled at 1 hour interval for analysis, Also, BSEC with BDF 20 resulted in lower than with diesel fuel. Since the biodiesel fuel used in this study includes oxygen of about 11%, it could influence the combustion process strongly. So, BDF 20 resulted in lower emissions of carbon monoxide, carbon dioxide, and smoke emissions without special increase of oxides of nitrogen than diesel fuel. It was concluded that there was no unusual deterioration of the engine, or any unusual change in exhaust emissions from using the BDF 20.

• Journal of the Korean Society of Combustion
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• v.20 no.3
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• pp.13-20
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• 2015

The performance of a direct-injection diesel engine often depends on the strength of swirl or squish, the shape of combustion chamber, the number of nozzle holes, etc. This is natural because the combustion in the cylinder was affected by the mixture formation process. Since the available duration to make the mixture formation of air-fuel is very short, it is difficult to make complete mixture. Therefore, an early stage of combustion is violent, which leads to the weakness of noise and vibration. In this paper, the combustion process of a common-rail diesel engine was studied by employing two kinds of pistons. One has several cavities on the piston crown to intensify the squish during the compression stroke in order to improve the atomization of fuel, we call this multi cavity piston in this paper. The other is a toroidal single cavity piston, generally used in high speed diesel engines. To take photographs of flame and flaming duration, a four-stroke diesel engine was remodeled into a two-stroke visible single cylinder engine and a high speed video camera was used.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.533-540
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• 2014

The remanufacturing industry for automotive parts is a major issue which affects the environment protection and CO2 reduction throughout the world. Beside this, remanufacturing technologies of worn-out diesel engines have been developing to make as close to new as possible. In this study, the characteristics of the engine-power output and exhaust emissions of remanufactured diesel engine by hydrogen enrichment are evaluated by measuring the engine and vehicle test. Moreover, with worn-out diesel engine and first generation common-rail engine, we compared by testing their characteristics, resulting in the restoration of engine-power output more than 93%, as well as marvelously reduces the THC and NOx emission. At a guess, high pressure injection of diesel increases fuel atomization characteristics with excellence combustion efficiency, resulting in reduction of THC emission. Also, rapid cooling of EGR decreases combustion temperature, resulting in reduction of NOx emission. Consequently, these remanufacturing for diesel engine enables worn-out diesel engine to have restoration to the original state. Simultaneously achieved 2 goals called that CO2 emission reduction and protection of environment by remanufacturing engine.

• 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).

• Journal of Power System Engineering
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• v.18 no.5
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• pp.156-163
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• 2014

Diesel engine is most suitable one for biodiesel fuel because the compression-ignition diesel engine has desirable fuel consumption due to higher thermal efficiency and in addition, the improvement of the fuel consumption also leads to a reduction of $CO_2$ emission and then it does not need to have spark-ignition system, which means that there is less charge on the technic and complexity. In this study, the spray behavior characteristics of the vegetable palm oil were analyzed by using a common-rail injection system of commercial diesel engine and the results were compared with those obtained for the diesel fuel. The injection pressures and blend ratios of palm oil and diesel(BD3, BD5, BD20, BD30, BD50, and BD100) were the main parameters. The experiments were conducted for different injection pressures: 500bar, 1000bar, 1500bar, and 1600bar by setting injection duration to $500{\mu}s$. Consequently, it was found that there is no significant difference in the macro characteristics of the spray behavior(spray penetration and spray angle) in response to change in the blend ratio of palm oil and diesel at a fixed injection pressure. In particular, all experiments showed the spray angle about $12^{\circ}{\sim}13^{\circ}$.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.4
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• pp.55-64
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• 2014

This work was investigated on pilot injection strategy of blended fuels(Diesel-DME) for combustion and emissions in a single cylinder direct injection compression ignition engine. Diesel and DME were blended by the method of weight ratio. Weight ratios for diesel and DME were 95:05 and 90:10 respectively. dSOI between main and pilot injection timing was varied. A total amount of injected fuels(single injection) was adjusted to obtain the fixed BMEP as 4.2 bar in order to compare with the fuel conditions. Also, the amount of pilot injection fuel was varied by 5%, 10% and 20% of total injection fuel. The engine was equipped with common rail and injection pressure is 700 bar at 1200 rpm. As a result, when mixing ratio increase, indicated thermal efficiency was increased in comparison with DD 100 and CO, THC and smoke were lower than DD 100. The influence of reducing NOx by pilot injection was more effective than DD 100. When pilot injection quantity increase, abrupt increase of NOx was occured at pilot injection quantity of 20%.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.1
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• pp.53-58
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• 2013

In order to judge that non-esterified soybean oil could be used on diesel engine with electronic control of fuel injection system, The test of combustion performance using only gas oil, gas oil blended with esterified bio-diesel oil 5% and non-esterified soybean oil 5% were carried out. It is noticed that most performances of gas oil blended with esterified bio-diesel oil 5% and non-esterified 5% have similar characteristics but non-esterified bio-diesel oil 5% emitted smaller NOx, resulting from fuel NO.

• International Journal of Automotive Technology
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• v.5 no.4
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• pp.239-245
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• 2004

It has been recognized that alternative fuels such as Liquid Petroleum Gas (LPG) show less polluting combustion characteristics than diesel fuel. Furthermore, engine performance is expected to be nearly equal to that of the diesel engine if direct-injection stratified-charge combustion of the LPG can be adopted in the spark-ignition engine. However, spray characteristics of LPG are quite different from those of diesel fuel. understanding the spray characteristics of LPG and evaporating processes are very important for developing efficient and low emission LPG engines optimized in fuel injection control and combustion processes. In this study, the LPG spray characteristics and evaporating processes were investigated using the Schlieren and Mie scattering optical system and single-hole injectors in a constant volume chamber. The results show that the mixture moves along the impingement wall that reproduced the piston bowl and reaches in ignition spark plug. LPG spray receives more influence of ambient pressure and temperature significantly than that of n-dodecane spray.

• Journal of ILASS-Korea
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• v.17 no.3
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• pp.158-163
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• 2012

This paper presents spray characteristics of piezo-driven type common-rail injector and comparisons to those of solenoid-driven type. Experiments were conducted to measure spray penetraion and SMD distributions using a spray visualization system and PDPA (phase Doppler particle analyzer) system. Injection conditions including injection pressure and energizing durations were varied in order to analyzing effects of injection conditions on spray characteristics. Furthermore, ambient pressures were increased for keeping ambient gas density close to in-cylinder pressure of diesel engine. Results showed that injection delay of piezo-driven type injector was much shorter than those of solenoid driven type and exhibited enhanced atomization performances.