• 대한기계학회논문집B
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• 제35권9호
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• pp.933-938
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• 2011

본 연구는 비예혼합화염보다 화염길이가 짧고 당량비 조절을 통해 NOx 및 CO 배출량을 제어할 수 있는 예혼합방식의 버너를 설치하고, 버너와 열교환기 사이의 거리가 각각 30, 40, 50mm인 3종의 열교환기에 대해 당량비를 변화시킬 때 NOx 및 CO의 배출특성을 비교하고 열교환기의 열전달특성을 검토한 것이다. 실험결과 버너와 열교환기의 거리변화와 관계없이 당량비가 증가할수록 화염온도가 높아져 NOx 및 CO 배출량도 증가한다. 또한 CO 배출량은 버너와 열교환기 사이의 거리가 가까울수록 높게 나타난다. 본 실험범위에서 A type 열교환기(버너와 열교환기 사이 거리 30 cm)를 당량비 0.75(CO 94.5ppm, NOx 11.2ppm, 효율 84.1%)에서 운전하는 것이 최적조건으로 나타났다.

• 한국산학기술학회논문지
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• 제15권8호
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• pp.4729-4735
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• 2014

적극적인 환경보호를 위해 그동안 상대적으로 소홀하였던 오프로드 엔진에 대한 배기가스 배출 규제가 강화되고 있다. 본 연구에서는 NOx와 PM 배출물 특성을 고려하여 오프로드 디젤 엔진의 강건 설계를 수행하였다. 이를 위하여 실험계획법에 따라 배출물 NOx와 PM의 측정 실험을 수행하고 다구찌 기법으로 망소 SN 비를 산출하고 분산 분석을 수행하였다. NOx와 PM 배출량에 영향을 미치는 제어 인잘로 인젝터 홀 수, 연료 분사 시기, EGR 율을 선택하였으며 각 제어 인자에 대하여 2 또는 3 수준을 고려하여 직교 배열표를 작성하였고, 이에 근거하여 실험을 수행하였다. 망소 SN 비를 산출하고 델타 통계량을 계산하였다. 저부하 운전 조건에서는 분사 시기가 NOx 배출량에 가장 큰 영향을 미치며, EGR 율이 PM 배출량에 가장 큰 영향을 미치는 결과를 얻었다. 제어 인자들에 대한 신뢰수준은 90% 이상이었다.

• 대한기계학회논문집B
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• 제28권7호
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• pp.818-825
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• 2004

In this paper, the study of effects of flow parameters on flame structure and NOx emission concentration was performed in co-axial. laminar partially premixed methane/air flames. Such (low parameters as equivalence ratio(${\Phi}$), fuel split percentage($\sigma$), and mixing distance(x/D$\_$i/) were defined as a premixing degree and varied within ${\Phi}$=1.36∼9.52, $\sigma$=50∼100, and x/D$\_$i/=5∼20. The image of OH$\^$*/ and NOx concentration were obtained with an ICCD camera and a NOx analyzer. The flame structure observations show a categorization of partially premixed flames into three distinct flame regimes corresponding to ${\Phi}$<1.7(premixed flame structure), 1.7<${\Phi}$<3.3(hybrid structure), and ${\Phi}$>3.3(diffusion flame structure existing a luminous sooting region) at $\sigma$=75%, and x/D$\_$i/=10. As o decreases from 100% to 50%, and x/D$\_$i/ decreases, nonpremixed flame structure appear at low equivalence ratio relatively. In addition, the measured emissions for NOx rise steeply from ${\Phi}$=1.7, to ${\Phi}$=3.3, then constants ${\Phi}$>4.76. NOx emissions decrease with increase the level of premixing level. In conclusion, the main effect on flame structure and NOx production was at first equivalence ratio(${\Phi}$), and next fuel split percentage($\sigma$), and finally mixing distance(x/D$\_$i/).

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.7-8
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• 2012

The effects of interaction between partially premixed and premixed swirl flames on CO and NOx emissions were experimentally investigated using a hybrid/dual swirl jet combustor for a micro-gas turbine. Under the condition of constant angle ($45^{\circ}$) for outer swirl vane, the angle and direction of inner swirl vane installed for a partially premixed flame were varied as main parameters with a constant fuel flow rate for each nozzle. It was found that for all conditions, CO and NOx emissions were measured below 4 ppm and 15 ppm at 15% $O_2$, respectively, in a wide range of equivalence ratio (0.6~0.9). For co-swirl flows, CO emission increased dramatically as the angle of inner swirl vane increased from $15^{\circ}$ to $45^{\circ}$ near lean-flammability limit (i.e. equivalence ratio of 0.5). On the other hand, the case of swirl $angle=45^{\circ}$ provided the lowest NOx emission at higher equivalence ratios than 0.6. For counter-swirl flows, the case of swirl $angle=45^{\circ}$ extended the lean-flammability limit but higher NOx emissions were found compared to those of co-swirl flows. These results could be inferred by interaction between (inner) partially premixed and (outer) premixed swirl flames. However, these estimations were not clear yet because there was insufficient data on turbulent flow structure and fuel-air mixing in the present experimental approach.

• 한국연소학회지
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• 제14권4호
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• pp.17-24
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• 2009

Reburning is one of the most useful technologies for reducing nitric oxide in economically and technically. The reburning process was demonstrated as an effective NOx reduction method through injection of a secondary hydrocarbon fuel. An experimental study has been conducted to evaluate the effect of biomass reburning on NOx and CO formation in a light oil flamed combustion furnace. Reburning tests on NOx reduction of air-carried rice husk powder as the reburn fuel and light oil as the main fuel were performed in flames stabilized by a co-flow swirl and fuel staged burner, which was mounted at the front of the furnace. The results included flue gas emissions and temperature distribution in the furnace for several kinds of experimental conditions. It was observed clearly that NOx concentrations in the exhaust have considerably decreased due to effect of biomass reburning. The maximum NOx reduction rate was 42% when the reburn fuel fraction was 0.18. The CO emissions were kept under 42 ppmv in all experimental tests. And this paper makes clear that in order to decrease NOx concentration in the exhaust when the biomass reburning system is adapted, the control of some factors such as reburn fuel fraction and reburn zone fraction is very important.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.78-83
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• 2011

Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its high thermal efficiency and lower harmful emissions, including $CO_2$. Although the high octane value of natural gas increases engine output and efficiency due to the high compression ratio, this fuel is prone to such difficulties as a narrow limit of inflammability and a slow combustion speed in the lean burn operation domain, leading to unstable combustion and higher emissions of harmful exhaust gases. Hydrogen blended with natural gas can extend the lean burn limit while maintaining stable, efficient combustion and achieving lower NOx, hydrocarbon and green house gas emissions. In this study, the effect of hydrogen addition on an engine performance and NOx emission characteristics was investigated in a heavy duty natural gas engine. The results showed that thermal efficiency was increased and NOx emissions were reduced due to the expansion of lean operation range under stable operation. NOx emission can be significantly reduced with the retard of spark advance timing.

• 한국산학기술학회논문지
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• 제15권6호
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• pp.4002-4006
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• 2014

자동차 배출가스는 자동차에 의해 발생되는 일산화탄소, 탄화수소, 납 외에 사람의 건강 또는 생활 환경에 피해를 일으킬 염려가 있는 물질을 말한다. 배출가스를 감소시키기 위해서 다양한 기술을 개발하는 것도 중요하지만 현재 사용되어 지고 있는 요소를 분석하여 최적의 상태를 찾는 것도 중요한 사항이라 여겨진다. 본 연구는 냉각수에 함유되는 부동액이 배출가스에 영향을 미칠 수 있음에 착안하여 현재 국내에서 시판되고 있는 5개 회사제품의 부동액을 권고 수준의 양을 냉각수에 함유시켜 HC, NOx, $CO_2$ 배출량을 측정하고 배출가스에 미치는 영향을 파악하고자 하였다. 또한, 5개회사 부동액 제품에 대하여 냉각팬 구동시간과 NOx 배출량과의 상관관계를 살펴보고자 하였다. 엔진오일의 온도는 자동차 검사 규격에 맞도록 $90{\sim}93^{\circ}C$에 맞추었고, 수동기어를 사용하는 소형승용차의 검사 규격 속도 $40{\pm}2Km/h$에서 수행하였다. 실험결과 D사 부동액이 팬 작동시간이 가장 짧고, $CO_2$, NOx 배출량이 가장 적게 나타났다.

• Journal of Advanced Marine Engineering and Technology
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• 제28권3호
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• pp.516-521
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• 2004

In this paper, the effects of ethanol blended gasoline on emissions and their catalytic conversion efficiencies characteristics were investigated in gasoline engine with an electronic fuel injection. The results showed that the increase of ethanol concentration in the blended fuels brought the reduction of THC and $CO_2$ emissions from the gasoline engine. THC emissions were drastically reduced up to thirty percent. And brake specific fuel consumption was increased. but brake specific energy consumption was similar level. However. unburned ethanol and acetaldehyde emissions increased. The conversion efficiency of Pt/Rh based three-way catalysts and the effect of ethanol on CO and NOx emissions were investigated by the change of engine speed. load and air/fuel ratio. Furthermore, the ethanol blended fuel results in the reduction effect of THC. CO and NOx emissions at idle speed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.390-395
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• 2003

The effect of recirculated exhaust gas on exhaust emissions under four kinds of nozzle tip with the different fuel consumption rate are experimentally investigated by using an once-through boiler with FGR system. The purpose of this study is to develop the FGR control system for reducing NOx in a boiler. Intake and exhaust oxygen concentrations, and equivalence ratio are applied to discuss the effect of FGR rate on exhaust emissions at various fuel consumption rates. It is found that NOx emissions are decreased, while soot emissions are increased owing to the drop of intake and exhaust oxygen concentrations, and the rise of equivalence ratio as FGR rates are elevated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2186-2191
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• 2003

This study is to investigate the effects of water induction through the air intake system on the characteristics of combustion and exhaust emissions in diesel engine. The effects of water induction through the air intake port were considered in IDI diesel engine in this study. The formation of NOx was significantly suppressed by decreasing the gas peak temperature during the initial combustion process because the water play a role as a heat sink during evaporating in the combustion chamber, but the smoke was slightly increased with increased water amount. Also, NOx significantly decreased with increase in water amount. A simultaneous reduction in smoke and NOx emissions can be obtained when water is injected into the combustion chamber by retarding the fuel injection timing more than without water injection.