• 한국산업융합학회 논문집
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• 제17권4호
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• pp.234-244
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• 2014

Recently it has been focused that the automobile engine has developed in a strong upward tendency for the use of the high viscosity and poorer quality fuels in achieving the high performance, fuel economy, and emission reduction. Therefore it is not easy to solve the problems between low specific fuel consumption and exhaust emission control at motor cars. In this study, it is designed and used the engine test bed which is installed with turbocharger and intercooler. In addition to equipped using CRDI by controlling injection timing with mapping modulator, it has been tested and analyzed the engine performance, combustion characteristics, and exhaust emission as operating parameters, and they were engine speeds(rpm), injection timing(bTDC), and engine load(%). From the result of an experimental analysis, peak cylinder pressure and the rate of pressure rise were increased, and the location of it was closer toward top dead center according to the increasing of engine speed and load, and with advancing injection timing. The combustion characteristics are effected by fuel injection timing due to be enhanced the mass burned fraction. Using the engine dynamometer for analyzing the engine performance, the engine torque and power have been enhanced according to advancing the fuel injection timing. In analyzing of exhaust emission, there has been a trade-off between PM and NOx with increasing of engine speed and load, and with advanced injection timing. The experimental data are shown that the formation of NOx has increased and PM, vice versa.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.267-270
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• 2014

Since contaminants of syngas obtained from the biomass gasification are removed, the syngas is clean fuel. In this study a high-efficiency energy production system is developed. The system produces electricity using a waste pressure and feeds a low-pressure steam to Dyeing industrial complex. Also, iron oxide derived from dyeing sludge is utilized as a self-catalyst to reform a tar and reduce a tar emission from gasifier. This system increases the amount of syngas and finally achieves a highly efficient gasification.

• 대한기계학회논문집B
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• 제27권11호
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• pp.1630-1636
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• 2003

Automobile companies and research institutions in leading automobile-manufacturing nations have recently been very active with research regarding the HCCI engine for use in future vehicles. Because HCCI engines take advantage of high compression ratio and heat release rate, they exhibit high efficiency found in compression ignition engines. HCCI engines also utilize a lean air/fuel ratio resulting in low emissions of NO$_{x}$ and PM (particulate matter). The objective of this research is to determine the effects of EGR rate on the combustion processes of HCCI. for this purpose, a 4-cylinder, compression ignition engine was converted into a HCCI engine, and a heating device was installed to raise the temperature of the intake air and also to make it more consistent. In addition, a pressure sensor was inserted into each of the cylinders to investigate the differences in characteristics among the cylinders. The experimental study of the effects of EGR rate on various gas emissions, engine performance, etc. should prove to be a valuable source of information for the development of the HCCI engine.e.

• 한국자동차공학회논문집
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• 제18권6호
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• pp.91-97
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• 2010

This paper described the effects of DME blended fuel on the engine combustion and emission characteristics of four cylinder CRDI diesel engine. Biodiesel was added into the DME fuel in order to improve the low kinematic viscosity of DME fuel. In this work, the experiment was performed under th various injection timings and injection strategy at constant engine speed and engine load. To maintain the fuel pressure and temperature, pressure and temperature controllers were installed to the DME fuel system. The results show that ignition delay was shortened and combustion duration was extended when DME blended fuel is supplied. Despite of slightly higher NOx emission with DME blended fuel at equal conditions in comparison with those of diesel fuel, the engine showed lower HC and CO emission characteristics.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.651-663
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• 2017

$30^{\circ}-15^{\circ}$ 노즐의 실험결과와 FLUENT, 경계층 적분법, Bartz 예측식을 사용하여 수치계산한 대류열전달계수를 서로 비교하였다. 또한 NASA HIPPO 노즐을 대상으로 FLUENT와 경계층 적분법을 이용하여 연소가스특성에 따른 대류열전달계수를 계산하고 압력과의 상관관계를 비교하였다. NASA HIPPO 노즐을 대상으로 열반응 해석을 실시하여 연소가스특성에 따른 삭마두께와 숯 깊이를 비교하였다.

• 한국분무공학회지
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• 제12권1호
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• pp.1-10
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• 2007

The low frequency combustion instability phenomena generated by pressure drop oscillation such as propellant shake in feed line are studied. To generate the flowrate oscillation by the pressure pulsation up to 400Hz without flow discontinuities and cavitations, a hydrodynamic mechanical pulsator of rotating disk type was produced. Injection pressure conditions are 5, 7 and 9 bar and pressure fluctuation frequency conditions are 0, 4, 6 and 8 Hz. When the injection pressure was oscillated by a mechanical pulsator, the spray shape was pulsated regularly. During the pulsated state of the spray with a mechanical pulsator, the spray characteristics, such as spray angle and liquid film thickness in orifice exit, were measured and compared with those in steady state without a mechanical pulsator. Though the mean injection pressure was fixed in the steady and fluctuating state, there were some differences in all measured values, i.e. liquid film thickness and spray cone angle, between both states.

• 에너지공학
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• 제23권3호
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• pp.181-185
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• 2014

본 논문은 카놀라 바이오디젤 혼합연료를 승용디젤엔진에 적용하였을 때 나타나는 연소 및 배기배출물 특성에 관한 연구이다. 본 연구에서는 카놀라 바이오디젤을 20%, 40%를 ULSD 80%, 60%와 체적비로 혼합한 혼합연료를 사용하여 ULSD 결과 데이터와 비교하였다. 엔진 회전속도, 엔진부하, 연료분사압력 변화를 실험변수로 사용하였으며. 카놀라 바이오 디젤의 혼합비가 증가 할수록 NOx 배출량은 증가하였지만, Soot 배출량은 감소하는 결과를 나타내었다. 또한 Soot 배출량은 낮은 연료분사압력에서 높은 배출량을 보였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
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• pp.119-122
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• 2005

고온과 고속의 열악한 환경 속에서 발생하는 비행체의 삭마현상은 일반적으로 상변화를 수반하는 유체의 유동, 에너지 전달, 질량전달, 화학반응이 수반되기 때문에 해석과정이 복잡하다. 본 연구에서는 액체로켓엔진의 흑연노즐에 대하여 1차원적으로 삭마현상을 수치해석하고, 실험을 통하여 이를 비교 검토하였다. 낮은 연소압력과 산화제/연료비에서는 삭마가 거의 이루어지지 않았으며, 연소압력과 혼합비가 낮은 경우에는 해석결과의 신뢰도는 낮고 정상작동 구간에서의 해석결과와 실험결과가 차이가 많은 것으로 보아 화학적 삭마 외에 기계적 삭마도 상당하다.

• 한국수소및신에너지학회논문집
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• 제20권6호
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• pp.464-470
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• 2009

In order to analysis the possibility of high expansion and performance without backfire in a hydrogenfueled engine using external mixture injection, combustion characteristics and performance enhancement were analyzed in terms of retarding valve timing and increasing the boosting pressure. As the results, it was found that thermal efficiency increased by retarding intake valve timing with the same level of supplied energy is over 6.6% by the effect of high expansion including effect of combustion enhancement due to supercharging. It was also shown that the achievement of high power (equal to that of a gasoline engine), low brake specific fuel consumption and low emission (NOx of less than 16 ppm) without backfire in a hydrogen-fueled engine is possible around a boosting pressure of 1.5 bar, intake valve opening time of TDC and $\Phi$=0.35 in fuel-air equivalence ratio.

• 한국자동차공학회논문집
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• 제15권2호
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• pp.1-7
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• 2007

The effect of injector geometries including the injection angle and number of nozzle holes on homogeneous charge compression ignition (HCCI) engine combustion has been investigated in an automotive-size single-cylinder diesel engine. The HCCI engine has advantages of simultaneous reduction of PM and NOx emissions by achieving the spatially homogenous distribution of diesel fuel and air mixture, which results in no fuel-rich zones and low combustion temperature. To make homogeneous mixture in a direct-injection diesel engine, the fuel is injected at early timing. The early injection guarantees long ignition delay period resulting in long mixing period to form a homogeneous mixture. The wall-impingement of the diesel spray is a serious problem in this type of application. The impingement occurs due to the low in-cylinder density and temperature as the spray penetrates too deep into the combustion chamber. A hole-type injector (5 holes) with smaller angle ($100^{\circ}$) than the conventional one ($150^{\circ}$) was applied to resolve this problem. The multi-hole injector (14 holes) was also tested to maximize the atomization of diesel fuel. The macroscopic spray structure was visualized in a spray chamber, and the spray penetration was analyzed. Moreover, the effect of injector geometries on the power output and exhaust gases was tested in a single-cylinder diesel engine. Results showed that the small injection angle minimizes the wall-impingement of diesel fuel that results in high power output and low PM emission. The multi-hole injector could not decrease the spray penetration at low in-cylinder pressure and temperature, but still showed the advantages in atomization and premixing.