• Journal of ILASS-Korea
• /
• v.10 no.1
• /
• pp.24-34
• /
• 2005

Injection technology is one of the important technologies in a diesel engine. Many studies have done on the injection system. In this study, the fuel chamber geometry, the orifice ratio and the needle lift of the injection valve for a marine diesel engine are varied, and simulated. The result shows that the nozzle hole size has influence on the rail pressure and injection duration sensitively. The decrease of the static pressure at the nozzle hole entrance and the increase of the dynamic pressure on the outlet surface are occurred with the increase of the nozzle hole diameter. The highest dynamic pressure of the outlet was occurred at the needle lift of 0.4mm and the nozzle hole diameter of 0.328mm in this test nozzle.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.448-452
• /
• 2008

2-stroke marine diesel engine has generally one exhaust valve and three fuel injection nozzle which are key component for engine's performance and combustion. Fuel injection and exhaust valve driving system are driven by rotating of camshaft. Rotation of crank shaft drives the cam shaft through gear train that is composed of $3{\sim}4$ gear wheels. Gear column supporting the gear wheel has to bear against the dynamics forces by engine running as well as gearing forces. In this paper, structural analysis for engine structure and fatigue strength assessment of welded joint is shown. Repeatedly full cyclic simulation during one cycle is performed to investigate the structural behavior of engine. Fatigue analysis is carried out based on IIW using submodeling technique to obtain more detailed stress distribution.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.14 no.3
• /
• pp.35-43
• /
• 2006

A four-stroke four-cylinder turbocharged diesel engine can be fitted with various types exhaust system. In this paper, the impacts of exhaust system design on scavenging performance and wave action characteristic during valve overlap are investigated by using one-dimensional gas dynamic code. This work shows that a huge reflected exhaust pressure waves which reaches the exhaust port during valve overlap period is crucial design factor which determines quality and quantity of the fresh charge. Hence pressure wave that reaches the exhaust port of the cylinder during the valve overlap sequence should be weakened for good scavenging performance. This paper describes advantages and disadvantages of the various exhaust systems applied to a turbocharged and intercooled 4-cylinder diesel engine system in terms of scavenging efficiency and engine performance. To verify the computational results, experimental comparison has also performed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.5
• /
• pp.124-129
• /
• 2010

The direct injection (DI) diesel engine has become a prime candidate for future transportation needs because of its high thermal efficiency. However, nitrogen oxides (NOx) increase in the local high temperature regions and particulate matter (PM) increases in the diffusion flame region within diesel combustion. Therefore, the demand for developing hybrid system consist of exhaust gas recirculation (EGR) and aftertreatment system as well as diesel particulate filter (DPF) or lean NOx trap (LNT) should be applied. The variation of EGR rate due to the malfunction of EGR valve can affect not only the combustion stability of engine but also the performance of aftertreatment system. In this research, 2.0 liter 4-cylinder turbocharged diesel engine was used to investigate the combustion and emission characteristics for various operating conditions with EGR. While the fuel consumption was increased with increase of EGR rate, NOx emission was improved by maximum 90% at low speed, low load operating condition. To achieve combustion stability and reliability of aftertrearment system with minimum penalty in fuel consumption and emissions, the fault diagnosis of EGR malfunction must be employed.

• Journal of ILASS-Korea
• /
• v.10 no.3
• /
• pp.45-53
• /
• 2005

The purpose of this study is to analyze that intake port swirl and fuel injection system have an effect on the engine performance in a turbocharged D.I. diesel engine of the displacement 9.4L. As result of steady flow test, when the valve eccentricity ratio moved to cylinder wall, the flow coefficient and swirl intensity is increased. And as the swirl is increased, the mean flow coefficient is decreased, whereas the Gulf factor is increased. Through this engine test, it can be expected to meet performance and emissions by the following applied parameters; the swirl ratio is 2.43, injection timing is BTDC 13oCA and compression is 15.5.

• Journal of Mechanical Science and Technology
• /
• v.16 no.7
• /
• pp.986-998
• /
• 2002

Flow and spray characteristics are critical factors that affect the performance and exhaust emissions of a direct injection diesel engine. It is well known that the swirl control system is one of the useful ways to improve the fuel consumption and emission reduction rate in a diesel engine. However, until now there have only been a few studies on the effect of flow on spray. Because of this, the relationship between the flow pattern in the cylinder and its influence on the behavior of the spray is in need of investigation. First, in-cylinder flow distributions for 4-valve cylinder head of DI (Direct Injection) Diesel engine were investigated under steady-state conditions for different SCV (Swirl Control Valve) opening angles using a steady flow rig and 2-D LDV (Laser Doppler Velocimetry). It was found that swirl flow was more dominant than that of tumble in the experimented engine. In addition, the in-cylinder flow was quantified in terms of swirl/tumble ratio and mean flow coefficient. As the SCV opening angle was increased, high swirl ratios more than 3.0 were obtained in the case of SCV -70° and 90°. Second, spray characteristics of the intermittent injection were investigated by a PDA (Phase Doppler Anemometer) system. A Time Dividing Method (TDM) was used to analyze the microscopic spray characteristics. It was found that the atomization characteristics such as velocity and SMD (Sauter Mean Diameter) of the spray were affected by the in-cylinder swirl ratio. As a result, it was concluded that the swirl ratio improves atomization characteristics uniformly.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.4
• /
• pp.37-43
• /
• 2003

The exhaust gas recirculation (EGR) is needed for one of various strategies to reduce NOx emission. But to get the proper EGR rate, the intake and exhaust system become complicated, also application of EGR system is difficult because of the penalty in fuel consumption and the increase in particulate matter. This study is focused on the development of EGR valve using the electrical method. The effects of EGR on the characteristics of NOx, CO, CO2 emissions and particulate mater have been investigated using small-displacement size 0.8-liters engine of diesel passenger car operating at several loads and speeds. After the analysis and comparison between conventional E-EGR valve and developed E-EGR valve performance by test bench, the estimation of vehicle application was executed through the EGR map and CVS-75 test result measured on the chassis dynamometer.

• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.5
• /
• pp.86-96
• /
• 2000

This study is to consider that the helical intake port flow and fuel injection system have effects on the characteristics of engine performance and emissions in a turbocharged DI diesel engine of the displacement 9.4L. The swirl ratio for ports was modified by hand-working and measured by impulse torque swirl meter, For the effects on performance and emission, the brake torque, BSFC were measured by engine dynamometer and NOx, smoke were by gas analyzer and smoke meter. As a result of steady flow test, when the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased, And as the swirl is increased, the mean flow coefficient is decreasing, whereas the gulf factor is increasing. Also, through engine test its can be expected to meet performance and emission by the following applied parameter; the swirl ratio is 2.43, injection timing is BTDC $13^{\circ}$CA and compression is 15.5.

• Journal of Energy Engineering
• /
• v.17 no.4
• /
• pp.198-203
• /
• 2008

The objective of the research was to study the effects of Miller cycle in a modified using diesel engine. The engine was dedicated to natural gas usage by modifying pistons, fuel system and ignition systems. The engine was installed on a dynamometer and attached with various sensors and controllers. Intake valve timing, engine speed, load, injection timing and ignition timing are main parameters. The results of engine performances and emissions are present in form of graphs. Miller Cycle without supercharging can increase brake thermal efficiency and reduce brake specific fuel consumption. The injection timing must be synchronous with valve timing, speed and load to control the performances, emissions and knock margin. Throughout these tested speeds, original camshaft is recommended to obtain high volumetric efficiency. Retard ignition timing can reduce $NO_x$ emissions while maintaining high efficiency.

• Journal of Biosystems Engineering
• /
• v.33 no.6
• /
• pp.379-383
• /
• 2008

A CRDI diesel engine used to commercial vehicle was fueled with diesel fuel and 20% biodiesel blended fuel (BDF 20%) and tested at the Seoul-10 mode for 150 hours. Engine dynamometer testing was completed at regularly scheduled intervals to monitor the engine performance and exhaust emissions. To check the engine parts (valve, injector), the engine was inspected after 150 hours running test. It was concluded that there was no unusual deterioration of the engine, or the changes in engine power (below 1.9%), smoke (below 4.1%), NOx (below 3.7%) and durability characteristics in spite of operation of 150 hours run with BDF 20%. The difference of kinetic viscosity for engine oil (before and after durability testing) was below 0.19% at $100^{\circ}C$.