• 에너지공학
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• 제21권4호
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• pp.385-392
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• 2012

본 연구는 현재 콘덴싱 보일러에 많이 사용하는 다공성 소재중에서 메탈화이버(metal fiber, MF) 및 세라믹(ceramic, CM)으로 제작한 평판형 버너에 대해 연소 및 열특성을 비교 검토하고 그 결과를 향후 개발할 EGR(Exhaust gas recirculation) 콘덴싱 보일러에 적용할 버너 선정의 기초자료로 활용하는 것을 목적으로 한다. CO 배출량은 CM이 MF보다 높았고 NOx 배출량은 MF가 CM보다 높게 나타났다. 버너열량 변화시에는 버너열량이 클수록 효율이 높게 나타났으며 버너 소재별 열효율은 버너열량 변화와 관계없이 MF가 CM보다 높게 나타났다. 본 실험범위에서 KS B 기준과 EN 677기준을 근거로 비례제어, 열효율, CO 및 NOx 배출량을 고려할 때 버너 소재는 MF가 적절하며 당량비는 0.8일때가 최적 운전조건으로 판단된다.

• 한국분무공학회지
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• 제25권4호
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• pp.178-187
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• 2020

The current emission regulations, US Tier-4 and EU Stage-V, are only able to satisfy the regulations when all currently mass-produced emission reduction technologies such as EGR, DOC, DPF, and SCR are applied. Therefore, in this study, for the application of the Urea-SCR system to non-road diesel engines, the database was established by measuring the NO, NO2 concentration and calculating the NO2/NOx ratio based on the catalyst temperature and exhaust mass flow rate. Also, based on the measured NO2/NOx ratio data, a mathematical model was proposed to predict the NO2/NOx ratio at SCR catalyst, and the suitability of the model was verified through steady-state and transient mode. As a result of comparing the NO2/NOx ratio measured at the DOC outlet under the steady-state condition to two model values separately, the R2 was 0.9811 for the 3D map model and 0.9303 for the mathematical model. And in the case of the NO2/NOx ratio measured at the DPF outlet, the R2 was 0.9797 for the 3D map model and 0.935 for the mathematical model. It was confirmed that the R2 with the model value of the 3D Map of the mathematical model in the transient mode is 0.957, which shows high reliability.

• 한국자동차공학회논문집
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• 제6권2호
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• pp.32-42
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• 1998

Lean burn gasoline engine is recognized as a promising way to meet better fuel economy. Lean burn engine is classified into port injection and direct injection(DI), DI is more active technique for improving fuel economy with ultra-lean operation, Nowadays, port injected lean burn engine has been produced by many Japan maker. Also, DI engine is also possible for production owing to improvement in control technique of spray, flow air fuel ratio. DI engine uses either homogeneous stoichiometric mixture or stratified mixture by controlling injection timing to be early or late respectively. HM(homogeneous mixture) is worse than SM(stratified mixture) in view of ultra-lean operation in partical load and Nox reducion by using EGR control. But, HM has advanteges in cold starting and emission reduction during transient operation, This paper describes experimental variables and bench test results of HM GDI engine.

• Journal of Advanced Marine Engineering and Technology
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• 제25권6호
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• pp.1244-1249
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• 2001

The characteristics of engine performance with fuel injection system in D.I. diesel engine were studied in this paper A fuel injection system has an important role in the performance and emission gas in a diesel engine. In this paper, an experimental study has been performed to verify the effect of the performance and the emission gas with the factors such as diameters of an injection nozz1e hole, diameters of an injection pipe and injection timing in the fuel injection system. The authors have obtained the results that optimizing the factors of fuel injection system is siginificant to enhance the performance of the engine system and consumption ratio of fuel, smoke, and NOx.

• 동력기계공학회지
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• 제6권2호
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• pp.12-17
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• 2002

Recently, the world is faced with very serious problems related to the air pollution due to the exhaust emissions of the diesel engine. So, many of researchers have studied to reduce the exhaust emissions of diesel engine. This study was investigated for various exhaust emissions according to operating conditions in a turbocharged D.I. diesel engine. As a result of experiments in a test engine, the $CO_2\;and\;NO_x$ increased with increasing load, the $CO_2$ and CO decreased with increasing charge air pressure in manifold, the CO decreased with increasing cooling fresh water temperature, and the $NO_x$ decreased with worming cooling fresh water before engine start.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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• pp.25-28
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• 2013

This study presents both experimental and numerical investigation of ignition characteristics of n-heptane and n-butanol mixture. The $O_2$ concentration was fixed to 9-10% to make high exhaust gas recirculation(EGR) rate condition. Experiments were performed using a rapid compression machine. In addition, a numerical study of the ignition delay time was performed using CHEMKIN codes to validate experimental results and predict chemical species after combustion process. The results showed that the ignition delay time increased with increasing n-butanol ratio and the reactivity decreased by low $O_2$ concentration.

• 한국분무공학회지
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• 제24권4호
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• pp.194-202
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• 2019

A mixture preparation strategy was proposed and evaluated in a diesel-natural gas dual-fuel engine to reduce hydrocarbon (HC) and carbon monoxide (CO) emissions under low load conditions. An experimental investigation was conducted in a single-cylinder compression-ignition engine. Natural gas was supplied with air during the intake stroke, and diesel was injected directly into the combustion chamber during the compression stroke. First, effects of diesel start of energizing (SOE) and natural gas substitution ratio on the combustion and exhaust gas emissions were analyzed. Based on the results, the mixture preparation strategy was established. A low natural gas substitution ratio and a high exhaust gas recirculation (EGR) rate were effective in reducing the HC and CO emissions.

• 한국수소및신에너지학회논문집
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• 제19권6호
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• pp.474-481
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• 2008

수소 기관에서 역화없이 고성능과 저$NO_x$를 실현시키기 위하여 밸브 타이밍 변화에 따른 흡기관 분사식 수소 기관의 성능을 파악하고 가솔린의 경우와 비교하였다. 그 결과 흡기밸브 타이밍은 역화억제와 성능향상에 큰 영향을 미치는 것을 확인하였다. 흡기밸브타이밍의 진각은 역화를 억제하며 효율과 출력을 동시에 향상된다. 비록 흡기밸브 타이밍 변화에 의해 NOx는 증가하지만, 희박영역인 출 ${\Phi}=0.5$에서 현저히 감소된다. 또한 열효율은 ${\Phi}=0.5$ 토크는 ${\Phi}=1.0$에서 가장 높게 나타난다. 흡기밸브 타이밍을 $ATDC20^{\circ}$에서 TDC로 변화시켰을 때, ${\Phi}=1.0$에서 토크는 약 28% 증가되고, ${\Phi}=0.5$에서 효율은 약 7%향상된다.

• 대한기계학회논문집
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• 제17권6호
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• pp.1633-1639
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• 1993

본 연구에서는 급속연소기술의 가솔린엔진에 적용을 목적으로 흡입과정시 강한 와류(swirl)를 생성하는 마스크부착 헤드(masked shroud head, MSH)형을 급속연 소형으로 제작하여 마스크부착 헤드형에서의 급속연소효과를 이온전류법에 의한 화염 속도를 측정하므로서 규명하려한다. 이온전류는 이온탐침계(ion probe)를 연소실 표면의 두 지점에 설치하여 검출하며, 이온전류 신호를 정성적인 방법으로 검증한 후 표준 헤드형과 마스크부착헤드형을 장착한 엔진에 대해서 화염전파 속도를 비교 측정 한다. 측정된 화염 전파속도는 정확한 연소특성 분석을 위해 각 사이클에서의 값을 표본으로 하는 통계적 방법으로 처리한다.

• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.106-113
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• 2016

Lean burn engine, classified into port injection and direct injection, is recognized as a promising way to meet better fuel economy. Especially, LPG direct injection engine is becoming increasingly popular due to their potential for improved fuel economy and emissions. Also, LPDi engine has the advantages of higher power output, higher thermal efficiency, higher EGR tolerance due to the operation characteristics of increased volumetric efficiency, compression ratio and ultra-lean combustion scheme. However, LPDi engine has many difficulties to be solved, such as complexity of injection control mode (fuel injection timing, injection rate), fuel injection pressure, spark timing, unburned hydrocarbon and restricted power. This study is investigated to the influence of spark timing, fuel injection position and fuel injection rate on the combustion stability of LPDi engine. Piston shape is constituted the bowl type piston. The characteristics of combustion is analyzed with the variations of spark timing, fuel injection position and fuel injection rate (early injection, late injection) in a LPDi engine.