• Tribology and Lubricants
• /
• v.31 no.6
• /
• pp.245-250
• /
• 2015

This study investigates the lubrication characteristics of fuel injection pumps with reference to different fuel oils. Medium-speed diesel engines use fuel oils with various viscosities, such as heavy fuel oil (HFO, which is a high-viscosity fuel oil) and light diesel oil (LDO, which is a low-viscosity fuel oil). When fuel oil with a low viscosity is used, both fuel oil and lubricating oil lubricate the system. Thus, the lubrication of the fuel injection pump is in a multi-viscosity condition when the fuel oil in use changes. We suggest three cases of multi-viscosity models, and divide the fuel injection pump into three lubrication sections: a, the new oil section; b, the mixed oil section; and c, the used oil section. This study compares the lubrication characteristics with variation of the multi-viscosity model, clearance. The volume of Section b does not affect the lubrication characteristics. The lubrication characteristics of the fuel injection pump are poor when high-viscosity fuel oil transfers to low-viscosity fuel oil. This occurs because the viscosity in the new oil section (i.e., Section a) dominates the lubrication characteristics of the fuel injection pump. However, the lubricant oil supply in the used oil section (i.e., Section c) can improve the lubrication characteristics in this condition. Moreover, the clearances of the stem and head significantly influence the lubrication characteristics when the fuel oil changes.

• Journal of ILASS-Korea
• /
• v.19 no.4
• /
• pp.221-226
• /
• 2014

This paper described the effect of split injections on the stability of combustion and emission characteristics in a direct injection gasoline engine at various operating conditions. In order to investigate the influence of direct injection gasoline engine, the fuel injection timing was varied direct fuel injection at various fuel pressure. The experimental apparatus consisted of GDI engine with 4 cylinder, EC dynamometer, injection control system, and exhaust emissions analyzer. The emission and combustion characteristics were analyzed for the fuel injection timing and fuel injection pressure strategies. It is revealed that CO and HC emissions are dramatically decreased at advanced injection timing. Also, engine performance is increased at increase fuel injection pressure.

• Journal of the Korean Society of Combustion
• /
• v.15 no.1
• /
• pp.1-11
• /
• 2010

In this study, the coupled simulation of fuel injection model and three-dimensional KIVA-3V code was tried to develop an algorism for predicting the effects of varying fuel injection parameter on the characteristics of fuel injection and emissions. The numerical simulations were performed using STAR-CD code in order to calculate the intake air flow, and the combustion characteristics is examined by KIVA-3V code linked with the conditional moment closure(CMC) model to predict mean turbulent reaction rate. Parametric investigation with respect to twelve relevant injection parameters shows that appropriate modification of control chamber orifice diameter, needle valve spring constant and nozzle chamber orifice diameter can significantly reduce NOx and soot emissions. Consequently, it is needed to optimize the fuel injection system to reduce the specific emissions such as NOx and soot.

• Journal of ILASS-Korea
• /
• v.4 no.2
• /
• pp.33-39
• /
• 1999

This paper presents the spray atomization characteristics of the high-pressure gasoline injector for the direct-injection gasoline engine. The gasoline sprays of the injector were minted into a pressurized spray chamber with a optical access at various ambient pressures. The atomization characteristics of fuel spray such as mean diameter, mean velocity of droplet were measured by the phase Doppler particle analyzer system. In order to investigate the effect of fuel injection pressure on the quantitative characteristics of spray, the global visualization and experiment of particle measurement in the fuel spray were investigated at 3, 5 and 7 MPa of injection pressure under different ambient pressure in the spray chamber. Based on the results of this work, the fuel injection pressure of fuel injector in gasoline direct-injection engine have influence upon distribution of the mean velocity and droplet size of fuel spray. Also, the influence of injection pressure on the velocity distribution at various measuring location were investigated.

• Journal of ILASS-Korea
• /
• v.15 no.1
• /
• pp.8-16
• /
• 2010

This paper present the diesel spray characteristics at different injection system parameters in a HSDI diesel engine. The spray characteristics was calculated by the coupled simulation of fuel injection system model and three-dimensional KIVA-3V code with TAB spray model. The relevant injection parameters are accumulator volume, control chamber initial volume, control orifice diameter, needle valve diameter and nozzle chamber initial volume, etc. Parametric investigation with respect to twelve relevant injection parameters showed that there was a significant advantage in varying control chamber initial volume, control chamber orifice diameter, and nozzle chamber orifice diameter with respect to effect the SMD and fuel injection speed. Consequently, in order to design the fuel injection system for spray characteristics, it seems reasonable to suppose to be optimized the fuel injection system.

• Journal of ILASS-Korea
• /
• v.22 no.1
• /
• pp.1-7
• /
• 2017

Recently, Performance and fuel efficiency of gasoline engines have been improved by adopting direct injection (DI) system instead of port fuel injection (PFI) system. However, injecting gasoline fuel directly into the cylinder significantly reduces the time available for mixing and evaporation. Consequently, particulate matters(PM) emissions increase. Moreover, as the emission regulations are getting more stringent, not only the mass but also the total number of PM should be reduced to satisfy the Euro VI regulations. Increasing the fuel injection pressure is one of the methods to meet this challenge. In this study, the effects of increased fuel injection pressures on combustion and emission characteristics were experimentally examined at several part load conditions in a 1.6 liter commercial gasoline direct injection engine. The main combustion durations decreased about $2{\sim}3^{\circ}$ in crank angle base by increasing the fuel injection pressure due to enhanced air-fuel mixing characteristics. The exhaust emissions and number concentration distributions of PM with particle sizes were also compared. Due to enhanced combustion characteristics, THC emissions decreased, whereas NOx emissions increased. Also, the number concentrations of PM, larger than 10 nm, also significantly decreased.

• Journal of ILASS-Korea
• /
• v.17 no.4
• /
• pp.178-184
• /
• 2012

The aim of this study was to compare the spray characteristics of a typical fuel (100% diesel, DME) and diesel-DME blended fuel in a constant volume combustion chamber (CVCC). The typical fuel (100% diesel, DME) and diesel-DME blended fuel spray characteristics were investigated at various ambient pressures (pressurized nitrogen) and fuel injection pressures using a common rail fuel injection system when the fuel mixture ratio was varied. The fuel injection quantity and spray characteristics were measured including spray shape, penetration length, and spray angle. Common types of injectors were used.

• Environmental Engineering Research
• /
• v.14 no.2
• /
• pp.95-101
• /
• 2009

Natural gas is a promising alternative fuel of internal combustion engines. In this paper, the combustion and emission characteristics were investigated on a natural gas engine at two different fuel injection timings during the intake stroke. The results show that fuel injection timing affects combustion processes. The optimum spark timing (MBT) achieving the maximum indicated mean effective pressure (IMEP) is related to fuel injection timing and air fuel ratio. At MBT spark timing, late fuel injection timing delays ignition timing and prolongs combustion duration in most cases. But fuel injection timing has little effect on IMEP at fixed lambdas. The coefficient of variation (COV) of IMEP is dependent on air fuel ratio, throttle positions and fuel injection timings at MBT spark timing. The COV of IMEP increases with lambda in most cases. Late fuel injection timings can reduce the COV of IMEP at part loads. Moreover, engine-out CO and total hydrocarbon (THC) emissions can be reduced at late fuel injection timing.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.7
• /
• pp.1013-1018
• /
• 2008

For a sequential port fuel injection natural gas engine, its combustion and emission characteristics at low loads are crucial to meet light duty vehicle emission regulations. Fuel injection timing is an important parameter related to the mixture formation in the cylinder. Its effect on the combustion and emission characteristics of a natural gas engine were investigated at 0.2 MPa brake mean effective pressure (BMEP)/2000 rpm and 0.26 MPa BMEP/1500 rpm. The results show that early fuel injection timing is beneficial to the reduction of the coefficient of variation (COV) of indicated mean effective pressure (IMEP) under lean burn conditions and to extending the lean burn limits at the given loads. When relative air/fuel ratio is over 1.3, fuel injection timing has a relatively large effect on engine.out emissions. The levels of NOx emissions are more sensitive to the fuel injection timing at 0.26 MPa BMEP/1500 rpm. An early fuel injection timing under lean burn conditions can be used to control engine out NOx emissions.

• Journal of ILASS-Korea
• /
• v.13 no.1
• /
• pp.1-8
• /
• 2008

It was investigated how fuel injection timing - early injection and later injection - in conjunction with throttle open rate effect the fuel-air mixing characteristics, Engine power, combustion stability and emission characteristics on a DI CNG spark Engine and control system that had been modified and designed according to the author's original idea. It was verified that the combustion characteristics were changed according to fuel injection timings and Engine conditions determined by different throttle open rates and rpm. It was found that the combustion characteristics greatly improved at the complete open throttle rate with an early injection timing and at the part throttle rate with a late injection timing. Combustion duration was governed by flame propagation duration in a late injection timing and by an early flame development duration in an early injection timing. As the result, we discovered that combustion duration is shortened, lean limit is improved, air-fuel mixing conditions controlled, and emissions reduced through control of fuel injection timing according to change of the throttle open rate.