• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.43-49
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• 2016

In this paper, purpose of study is emissions characteristics according to effects of heating value variations of CNG fuel in a dual-fuel engine fueled by diesel and natural gas. For heating value variation of CNG fuel, nitrogen gas was mixed with pure CNG fuel. So the higher heating value was changed from $10,400kcal/Nm^3$ to $9,400kcal/Nm^3$. Under one condition of CNG substitution rate was fixed at 80%, diesel fuel was injected at a fixed injection timing of 16 CAD BTDC and fuel pressure was also fixed at 110 MPa. The condition of tested engine was 1800 rpm and 500Nm. Emissions were sampled in exhaust pipe was located at downstream turbocharger. As a result, emissions characteristics were checked in heating value variations of CNG fuel with mixed nitrogen gas THC, $CH_4$ and CO emissions decreased and NOx and $CO_2$ increased.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.834-840
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• 2018

In this study, the characteristics of air pollutant emissions from ships' engines have been investigated by conducting E2 and E3 cycle mode tests. A engine 360Ps (Doosan L126TIH engine) and 400kW dynamometer Horiba-Schenck were utilized for engine tests. The FTIR analyzer and SPC were used to measure exhaust gas (NOx, SOx etc.) and PM (particulate matter), respectively. The results showed that the emissions of THC and CO produced from engine were increased with the increase of sulfur content in fuel oils at E2 and E3 cycle modes. The kinetic viscosity of the fuel increased as the sulfur content of the fuel increased, thereby the specific fuel oil consumption (SFC) of the engine improved. This result is considered to be due to improved combustion conditions due to increased average diameters of sprayed particles and due to increased kinetic viscosity under constant fuel injection pressure in this study. In the case of NOx emission, this study showed no significant change in amount of sulfur content.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.132-140
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• 2009

Recently, the interest in the development of high efficiency Diesel engine technology using alternative fuel has been on the rise and related studies are being performed. Therefore, the DME(Dimethyl Ether), an oxygen containing fuel as an alternative fuel for light oil that can be used for diesel engines since it generates very little smoke. But it is unavoidable that the modification of a fuel supply system in an engine to application of the DME fuel because of DME fuel properties. So, in this study, a DME high pressure pump for a common-rail fuel supply system has been composed and the test results of the pump have been presented. As the results of the tests, it is confirmed that DME pump inlet pressure, pump speed and common-rail pressure effects on the volumetric efficiencies of the pump. Finally, it is defined that the optimum plunger volume of a DME pump has to be extended to the minimum 150% compared to a Diesel pump plunger volume considering DME fuel properties and volumetric efficiencies characteristics at same specifications of the high pressure pump.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.128-134
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• 2007

Combustion performance and characteristics of high-pressure subscale liquid rocket combustors were studied experimentally. Four different models of combustor were considered in this paper. The high-pressure subscale combustor is composed of the mixing head, the water cooling cylinder and the nozzle. One model of the combustors employed regenerative cooling combustor in that the kerosene used for the chamber cooling is burned. This combustor was damaged due to a high frequency combustion instability occurred during a firing test. The results of the firing tests, comparison of performance, and characteristics of static and dynamic pressures of the combustors are described.

• Journal of Power System Engineering
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• v.15 no.5
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• pp.10-15
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• 2011

This paper describes the engine performance and combustion characteristics of a CRDI diesel engine, operated by electronically controlled diesel fuel injector with variable injection timing. This experiment focused on fuel injection timing and pressure about combustion characteristics of CRDI diesel engine. EGR was excepted because it would be furtherly analyzed with additional experiments. The experiment was conducted under the circumstance of engine torque for 4, 8, 12 and 16 kgf-m and fuel injection timing for $15^{\circ}$, $10^{\circ}$ and $5^{\circ}$ BTDC, at the engine speed of 1100, 1400, 1700 and 2000 rpm. Fuel injection was controlled to retard or advance initiation of the injection event by electronically controlled fuel injection unit injector on the personal computer. When fuel was injected into the cylinders of a CRDI diesel engine it would go through ignition delay before starting of combustion. Therefore, fuel injection timing of CRDI diesel engine had a significant effect upon performance and combustion characteristics. Depending on the injection timing the fuel consumption rate following the rotational speed and torque was 3~78 g/psh (1.7~30.6%). The range of fuel injection timing that resulted in low fuel consumption overall was BTDC 15-10 degrees.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.5
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• pp.455-461
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• 2015

A high-pressure fuel pump is a key component in a gasoline direct injection (GDI) engine; thus, understanding its flow characteristics is essential for improving the engine power and fuel efficiency. In this study, AMESim, which is a hydraulic analysis program, was used to analyze the performance of the high-pressure fuel pump. However, since AMESim uses a one-dimensional model for the system analysis, it does not accurately analyze the complicated flow characteristics. Thus, Fluent, computational fluid dynamics (CFD) software, was used to calculate the flow rates and net forces at the intake and discharge ports of the high-pressure fuel pump where turbulent flow occurs. The CFD analysis results for various pressure conditions and valve lifts were used as look-up tables for the AMEsim model. The CFD analysis results complemented the AMEsim results, and thus, improved the accuracy of the performance analysis results for the high-pressure fuel pump.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.128-133
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• 2006

Influence of changing combustor pressure on flame stabilization and nitrogen oxide (NOx) emission in the swirl-stabilized flame with secondary fuel injection was investigated. The combustor pressure was controlled by suction at combustor exit. Pressure index ($P{\ast}=P_{abs}/P_{atm}$), where $P_{abs}$ and $P_{atm}$ indicated the absolute pressure and atmosphere pressure, was controlled in the range of $0.7{\sim}1.3$ for each equivalence ratio conditions. The flammable limits of swirl flames were largely influenced by changing combustor pressure and they showed different tendency compared with laminar flames. Emission index showed maximum value near atmospheric condition and decreased with decreasing pressure index for overall equivalence ratio conditions. R.m.s of pressure fluctuations also showed similar tendency with nitric oxide emission. By injecting secondary fuel into flame zone, the flammable limits were extended significantly. Emission index of nitric oxide and r.m.s. of pressure fluctuations were also controlled by injecting secondary fuel. The swirl flames were somewhat lifted by secondary fuel with high momentum, hence low nitric oxide emission. This NOx reduction technology is applicable to industrial furnaces and air conditioning system by adopting secondary fuel injection.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.150-159
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• 2014

This study provides a brief introduction to application of the computational fluid dynamics to domestic development of combustion devices for liquid-propellant rocket engines. Multi-dimensional flow analysis can provide information on the flow uniformity and pressure loss inside the propellent manifold, from which the design selection can be performed during the conceptual design phase. Multi-disciplinary performance analysis of the thurst chamber can also provide key information on performance-related design issues such as fuel film cooling and thermal barrier coating conditions. Further efforts should be made to develop numerical models to resolve the mixing and combustion characteristics of LOX/kerosene near the injection face plate.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.4
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• pp.70-83
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• 1997

We made a selection of engine operating conditions in the natural aspiration type diesel engine as load and speed. The effects on the power, smoke emission and cylinder pressure characteristics of these variations in operating conditions were observed experimentally. Also, the smoke emission was predicted by using the Arrhenius equation and empirical equation of the smoke emission was made. At the same time, the correlations, between the combustion and smoke emission characteristic were examined. From the above results, it is clear that to prevent power dropping and to decrease exhaust fume whin the conditions are changed, one should improve the intake system. To do this, the best way is to lower the air-fuel mixing ratio. We found that the parameters of the indicated mean effective pressure, maximum pressure and its location and combustion duration, etc. change the motion in accordance with the conditions described above. Also, we found that the variation of the pressure cycle comes from an amplified variation of the early part of process. From the analysis of comparing combustion and exhaust fume, the exhaust fume is produced at the latter time of combustion and decreased when the combustion ratio is higher. Also, we developed a special formula which can predict the exhaust fume value according to the engine load and speed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.584-587
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• 2011

An internal flow aerodynamic test was performed for a Mach 5 scramjet engine. The test was done without fuel injection, as a preliminary test for the combustion test. Test engine is an engineering model with intake cross-section of $70mm{\times}200mm$ and total length of 1.7m. Test facility is a blowdown-type, high enthalpy, hypersonic facility. 19 pressures were measured through the holes on the model surface along the engine internal flow passage. It was found that the facility start is possible, and also supersonic flow is maintained inside the engine.