• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.231-236
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• 2003

HCCI(Homogeneous Charge Compression Ignition) combustion is an advanced combustion process explained as a homogeneously premixed charge of a fuel where air is admitted into the cylinder and compression ignited. It has possibility to reduce NOx by spontaneous auto-ignition at multiple points that allows very lean combustion resulting in low combustion temperatures. Particulate matters (PM) could be also reduced by the homogeneous combustion and no fuel-rich zones. Injection timing is extremely advanced to achieve homogeneous charge where a diesel fuel could not be vaporized sufficiently due to low pressure and low temperature condition. Also the over-penetration could be a severe problem. The small injection angle and multi-hole injectors were applied to solve these problems. Dimethyl ether (DME) as an altenative fuel was also applied to relive the bad vaporization problem associated with early injection of diesel fuel. Neat DME has a very high cetane rating and high vapor pressure. Contained oxygen reduces soot during the combustion. Experimental result shows DME can be easily operated in an HCCI engine. PM shows almost zero value and NOx is reduced more than 90% compared to direct-injection diesel engine operating mode but problem of early ignition needs more investigation.

• 한국연소학회지
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• 제21권3호
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• pp.32-38
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• 2016

This paper aims to predict oxidation amounts of catalyst and heat produced through passive regeneration on DPF according to different EGR rates and loads of off-road engines. Soot oxidation model and parameter assumption model were used for the test. Engine data were measureed with 25%, 50% and 75% of 1600 RPM loads and with 0% and 30% of EGR rates in order to estimate parameters. Oxygen levels calculated on the DPF downstream and oxygen levels measured were compared through all of the experimental conditions for validating the model. Oxidation rates on DPF according to different EGR rates and oxygen levels on the DPF downstream were estimateed successfully, which can be applied for off-road vehicles.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.76-81
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• 2011

Exhaust gas recirculation is the well-known and widely used NOx reduction technology for diesel engines. More effective EGR cooler has been developed and applied to diesel engines to meet the reinforced emission regulation. However, the contaminated EGR cooler by diesel exhaust gas reduces the performance of the engine and NOx reduction rate. The buildup of deposits in EGR coolers cause significant degradation in heat transfer performance, often on the order of 20~30%. Deposits also increase pressure drop across coolers and thus may degrade engine efficiency under some operation conditions. In this study, as a solution for this problem, DOC assisted EGR cooler is designed and then investigated to reduce fouling and its impact on cooler performance. A single channel EGR cooler fouling test apparatus and soot particle generator were developed to represent the real EGR cooler and exhaust gas of diesel engine. EGR cooler effectiveness of the case with catalyst of pt 30g/ft3 decreased just up to 5%. This value was 45% less compared to the case without catalyst which decreased up to 9% after 10hours experiments.

• 한국응용과학기술학회지
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• 제34권1호
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• pp.12-24
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• 2017

현재 국내 엔진오일-윤활유가 배출가스에 미치는 영향에 대한 연구가 미비한 실정이며 그 실험 방법 또한 확립되어 있지 않다. 이에 엔진을 이용한 윤활유 성상 변화가 PM(Particulate Matters) 배출에 미치는 영향 평가방법을 수립하여 윤활유의 성상 및 열화가 자동차 성능과 환경성에 미치는 영향을 연구하고자 한다. 윤활유 소모 및 연소로 인한 DPF(Diesel Particulate Filter) 및 후처리 장치에 미치는 영향을 평가하는 것이 중요하며, 특히 DPF의 재생과정에서 생성되는 PM(Particulate Matters)과 Ash가 DPF에 미치는 장기적인 영향과 내부 변형 및 내구성에 대한 평가와 연구가 필요하다. 본 연구에서는 정형화 되지 않은 시험모드를 개발하였으며, 내구시험결과 High SAPs의 경우 Low SAPs(Sulfated Ash, Phosphorus and Sulfuate)보다 DPF내 Ash의 축적량이 많은 것을 확인하였으며, EGR(Exhaust Gas Recycling)의 Fouling 현상 가속화에 영향을 미칠 것으로 확인하였다. 본 연구결과물을 토대로 윤활유의 기유, 첨가제, 열화 등에 따른 엔진 및 차량의 성능과 배출가스 특성을 기술정책 자료로서 활용하도록 방향을 도모하고 시험 방법을 확립하고자 한다.

• Asian Journal of Atmospheric Environment
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• 제9권1호
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• pp.66-77
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• 2015

In order to survey the seasonal variation of the chemical composition of particulate matter of $2.5{\mu}m$ or less ($PM_{2.5}$), $PM_{2.5}$ was sampled from 8 February 2013 to 31 March 2014 in an industrial area of Chiba Prefecture, Japan. Chemical measurements of the sample included: ionic components ($Na^+$, $NH_4{^+}$, $Ca^{2+}$, $Mg^{2+}$, $K^+$, $Cl^-$, $NO_3{^-}$ and $SO_4{^{2-}}$), carbonaceous components - organic carbon (OC) and elemental carbon (EC), and water-soluble organic carbon (WSOC). Also, secondary organic carbon (SOC) was measured based using the EC tracer method, and char-EC and soot-EC were calculated from the analytical results. The data obtained were interpreted in terms of temporal variation. Of the overall mean value of $PM_{2.5}$ mass concentration obtained during the study period, ionic components, OC and EC accounted for 45.3%, 19.7%, and 8.0%, respectively. $NO_3{^-}$ showed a unique seasonal distribution pattern due to a dependence on temperature and absolute humidity. It was estimated that an approximate temperature of $14^{\circ}C$, and absolute humidity of $7g/m^3$ were critical for the reversible reaction of $NH_4NO_3(p){\leftrightharpoons}NH_3(g)+HNO_3(g)$. The amount of OC and EC contributing to the monthly $PM_{2.5}$ mass concentration was higher in autumn and winter compared to spring and summer. This result could be attributed to the impact of burning biomass, since WSOC and the ratio of char-EC/soot-EC showed a similar pattern during the corresponding period. From the comparison of monthly WSOC/OC values, a maximum ratio of 83% was obtained in August (summer). The WSOC and estimated SOC levels derived from the EC tracer method correlated (R=0.77) in summer. The high occurrence of WSOC during summer was mainly due to the formation of SOC by photochemical reactions. Through long-term observation of $PM_{2.5}$ chemical components, we established that the degree to which the above-mentioned factors influence $PM_{2.5}$ composition, fluctuates with seasonal changes.

• 한국화재소방학회논문지
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• 제28권6호
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• pp.8-12
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• 2014

현행 건축법은 건축물의 규모, 용도에 따라 화재확산방지와 재실자의 보호를 위하여 실내 마감 재료를 불연, 준불연, 난연재료로 시공하도록 규정하고 있으며, 가스 유해성 시험(KS F 2271)에 따라 해당 시료의 연소 생성물에 노출된 실험용 쥐의 평균행동정지시간을 측정하여 연소 생성물의 유해성을 평가하고 있다. 실험용 쥐를 대상으로 가스상, 입자상 물질의 복합적 유해효과를 분석한 결과인 평균행동정지시간이 15분의 노출 시험 중 9분 이내로 측정된 경우, 연소 유해성 평가 결과가 부적합한 것으로 판정한다. 이에 본 연구에서는 연소 생성물에 포함된 가스상, 입자상 물질 중에서 실험용 쥐의 행동정지에 미치는 영향이 큰 요소를 규명하기 위하여 연소 생성물에 포함된 입자상 물질의 입도 분석을 실시하여 위험도의 상관관계를 밝혔다.

• Tribology and Lubricants
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• 제34권6호
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• pp.292-299
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• 2018

The objective of this research is to investigate the impact of engine oil aging on PM(Particulate Matter), exhaust gases, and DPF. It is widely known that the specification of a lubricant and its consumption in an ICE considerably influences the release of regulated harmful emissions under normal engine operating conditions. Considering DPF clogging phenomena associated with lubricant-derived soot/ash components, a simulated aging mode is designed for DPF to facilitate engine dynamometer testing. A PM/ash accumulation cycle is developed by considering real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for ash accumulation. The test duration for DPF aging is approximately 300 h with high- and low-SAPs engine oils. Detailed engine lubricant properties of new and aged oils are analyzed to evaluate the effect of engine oil degradation on vehicle mileage. Furthermore, physical and chemical analyses are performed using X-CT, ICP, and TGA/DSC to quantify the engine oil contribution on the PM composition. This is achieved by sampling with various filters using specially designed PM sampling equipment. Using high SAPs engine oil causes more PM/ash accumulation compared with low SAPs engine oils and this could accelerate fouling of the EGR in the engine, which results in an increase in harmful exhaust gas emissions. These test results on engine lubricants under operating conditions will assist in the establishment of regulated and unregulated toxic emissions policies and lubricant quality standards.

• 대한기계학회논문집B
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• 제36권11호
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• pp.1065-1072
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• 2012

바이오디젤 연료는 그 안에 포함된 산소성분으로 인해 압축착화엔진에 사용했을 때 일반디젤 연료보다 더 적은 입자상 물질을 배출한다. 따라서 이 연료를 저온연소 기법에 적용하는 경우 보다 효과적으로 $NO_x$-PM을 동시 저감할 수 있고 그로부터 저온연소 운전영역의 확장을 기대할 수 있다. 이번 연구에서는 일반디젤과 대두유 기반의 바이오디젤 연료를 이용하여 산소농도 5~7%의 Dilution controlled regime에서 저온연소 운전을 구현하고 성능 및 배기 특성을 조사하였다. 엔진 실험 결과로부터 바이오디젤 연료의 경우 디젤에 비해 약 14% 낮은 발열량에도 불구하고 높은 세탄가 및 함산소 성질로 인한 연소효율 증가로 동일 연료량 분사 시 이보다 더 낮은 약 10~12% 정도의 출력이 감소함을 볼 수 있었다. 배기 측면에서도 바이오디젤 내 산소원자가 입자상물질의 산화반응을 촉진하여 최대 90%의 smoke 저감이 가능함을 관찰하였다. 또한 엔진 과급 실험으로부터 과급을 사용하여 저온연소 및 바이오디젤 사용으로 인한 출력 저하를 개선할 수 있음을 확인하였으며 과급과 바이오디젤 연료의 동시 적용을 통해 산소농도 11~12%의 EGR 가스 투입으로도 저온연소에 상응하는 PM-$NO_x$ 동시 저감이 가능함을 보여주었다. 이런 결과는 결국 이와 같은 과급 및 바이오디젤 연료의 적절한 조합으로부터 엔진 출력 향상과 배기특성 개선이 동시에 달성할 수 있고 이로부터 운전영역의 확대가 가능함을 의미한다.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.88-94
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• 2012

One of the effective ways to reduce both $NO_x$ and PM at the same time in a diesel CI engine is to operate the engine in low temperature combustion (LTC) regimes. In general, two strategies are used to realize the LTC operation-dilution controlled LTC and late injection LTC - and in this study, the former approach was used. In the dilution controlled regime, LTC is achieved by supplying a large amount of EGR to the cylinder. The significant EGR gas increases the heat capacity of in-cylinder charge mixture while decreasing oxygen concentration of the charge, activating low temperature oxidation reaction and lowering PM and $NO_x$ emissions. However, use of high EGR levels also deteriorates combustion efficiency and engine power output. Therefore, it is widely considered to use increased intake pressure as a way to resolve this issue. In this study, the effects of intake pressure variations on performance and emission characteristics of a single cylinder diesel engine operated in LTC regimes were examined. LTC operation was achieved in less than 8% $O_2$ concentration and thus a simultaneous reduction of both PM and $NO_x$ emission was confirmed. As intake pressure increased, combustion efficiency was improved so that THC and CO emissions were decreased. A shift of the peak Soot location was also observed to lower $O_2$ concentration while $NO_x$ levels were kept nearly zero. In addition, an elevation of intake pressure enhanced engine power output as well as indicated thermal efficiency in LTC regimes. All these results suggested that LTC operation range can be extended and emissions can be further reduced by adjusting intake pressure.