초기 직경 변화가 Toluene 액적의 Soot 생성에 미치는 영향

임영찬 ( Young Chan Lim ),서현규 ( Hyun Kyu Suh ) 한국분무공학회 2015 한국액체미립화학회지 Vol.20 No.4

The main purpose of this study is to provide the information of soot generation of toluene fuel droplet. To achieve this, this paper provides the experimental results on the different initial diameter of toluene droplet combustion characteristics conducted under equivalent ambient pressure (Pamb) and oxygen concentration (O2) conditions. Visualization of single fuel droplet was performed with high resolution CCD camera and visualization system. At the same time, ambient pressure (Pamb) and oxygen concentration (O2) were maintained by ambient condition control system. Soot volume fraction ( fv) was analyzed and compared on the basis of intensity ratio (I/I0) of background image. The result of soot generation was almost the same regardless of initial droplet diameter since thermophoretic flux is not much changed under the same ambient conditions. Soot standoff ratio (SSR) of 2 mm diameter showed unstable variation characteristics due to the short available measuring time.

화학반응 기반의 균질 연소 특성 조사를 통한 가연한계 경향성 추적

임영찬(Young Chan Lim),서현규(Hyun Kyu Suh) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6

세계적으로 환경오염물질 배출 규제에 대응하기 위해 차량에서 배출되는 배기 배출물을 저감 하고자 다양한 선행 연구들이 수행되었다. 특히, 탄화수소 연료 연소 시 저온과 고온 영역에서 발생하는 대표적인 연소 생성물인 일산화탄소(CO)와 질소산화물(NO_X)의 저감이 필수 사항이기 때문에, 직분사 엔진 연소 과정에서 이와 같은 배기 배출물 저감을 목표로 HCCI (Homogeneous charge compression ignition) 연소 기법을 적용한 많은 선행 연구가 수행되었고, HCCI 연소를 통한 배기 배출물 저감 가능성이 보고되었다. 일반적으로 HCCI 연소를 적용하기 위해 배기가스 재순환(EGR)을 가장 많이 활용하고 있으나, HCCI 연소 한계가 존재하며 이를 개선하기 위해 균질 연소 거동을 파악하기 위해 열·화학적인 비교 분석 연구가 반드시 수행되어야 한다. 따라서, 본 연구에서는 연소 메커니즘을 기반으로 분위기 온도, 분위기 압력, 당량비 변화에 따른 기상 연료의 균질 연소 특성을 연소 및 배기, 화학반응 특성 비교 분석을 통해 균질 연소 특성 파악이 가능한 맵 데이터를 구축하고, 이를 바탕으로 가연한계 경향성을 추적하여 가연한계를 예측하는 것을 목표로 하였다. 이를 위하여 정적 연소 및 엔진 연소 과정에서 나타나는 기상 연료의 균질 연소 특성과 화학반응 분석을 연소 메커니즘을 기반으로 연소 생성물 및 반응물의 몰분율, 화학반응 경로 분석, 연소 온도 비교 분석 연구를 통해 수행하였다. 또한, CVCC (Constant volume combustion camber) 및 다중 구역 HCCI 엔진 시뮬레이터를 활용하여 다양한 분위기 조건 변화에 따른 기상 연료의 가연한계 경향성을 추적하고 화학반응 경로를 정리하여 비교하였다. 연소 해석에 적용된 메커니즘은 상세화학반응 메커니즘을 기반으로 수정 보완된 연소 메커니즘을 사용하였고, 기상 연료의 모사 화학종은 CH₃OCH₃, n-C₇H₁₆, C₁₁H₂₂O₂, C₁₁H₂₀O₂ 화학종을 사용하여 DME, 디젤, 바이오디젤 모사 연료로서 각각 적용하였다. 해석에 적용된 메커니즘 및 해석 검증 연구는 균질 연소를 유도하기 위해 조기 분사 전략을 적용한 단기통 압축착화 엔진 실험 결과와 비교분석 하였다. 연소 메커니즘을 적용하여 계산된 HCCI 엔진의 실린더 압력 결과는 균질 연소를 유도하기 위해 분사 시기가 BTDC 60 deg, BTDC 25 deg로 적용된 엔진 실험 결과와 잘 일치하는 것으로 나타났다. 이를 통해 점화지연 특성 및 모사 연료의 기본적인 연소 데이터와 해석 연구에 적용된 연소 메커니즘의 신뢰성을 확인하였다. HCCI 엔진 연소 특성에서 나타난 최대 연소 온도 결과 분포는 분위기 온도 900 K, 분위기 압력 25 ~ 40 atm 조건에서 맵 데이터와 유사한 연소 거동 경향성을 보이는 가연한계 추적 결과를 확인하였다. 이러한 연소 온도 결과는 분위기 온도 및 당량비가 증가함에 따라 연료 반응성이 향상되어 연소 온도가 증가하였고, 연소 기간 동안 높은 연소 온도를 바탕으로 충분한 산소 농도를 유지하는 당량비 0.3 ~ 0.7 조건에서 연소 온도 증가와 함께 NO_X 배출량이 증가하는 경향을 보였다.

단파장 필터링을 통한 단일 액적 화염 내 CH₂O, CH, C₂ 화학종 분석 및 액적 연소 특성

임영찬(Young Chan Lim),서현규(Hyun Kyu Suh) 한국연소학회 2021 한국연소학회지 Vol.26 No.3

This paper was performed to observe the flame behavior of the biodiesel, diesel, and n-heptane single fuel droplets and analyze the CH₂O, CH, and C₂ species in a single droplet flame included combustion characteristics experimentally. In order to visualize the combustion process of test fuel droplets, droplet combustion visualization and analysis were conducted using a high-speed camera and a CCD camera coupled with a short wavelength filter. A single fuel droplet was formed on the stainless wire using a syringe and ignited by a heat source provided from the power supply equipment. It was shown that the ignition delay of an n-heptane fuel droplet was shorter than those of biodiesel and diesel fuel droplets due to a higher evaporation rate in the liquid phase. A longer flame extinction and the flame life-time were also observed in the biodiesel and diesel fuel droplets than most n-heptane fuel droplets. In the case of the diesel fuel droplet, it was found that the flame life-time was slightly increased than the biodiesel fuel droplet. The C₂ species produced in the flame during combustion of all fuel droplets were distributed throughout the flame, while the CH and CH₂O chemical species tended to be located in the flame front and center area. As a result of combustion analysis, the biodiesel, diesel, and n-heptane fuels were shown the changes of the CH₂O mole fraction according to the two-stage combustion characteristics, and the mole fraction of CH species was decreased by CH + O₂ and CH + H₂O chemical reactions.

분위기 조건이 Decane 액적의 Soot 생성에 미치는 영향

임영찬 ( Young Chan Lim ),서현규 ( Hyun Kyu Suh ) 한국분무공학회 2014 한국액체미립화학회지 Vol.19 No.4

The main purpose of this study is to provide basic information of droplet soot generation of decane fuel. To achieve this, this paper presents the experimental results on the decane droplet combustion conducted under various ambient pressure(Pamb), and oxygen concentration(O2) conditions. At the same time, the experimental study was conducted in terms of soot volume fraction(fv) and its maximum value. Also, visualization of single fuel droplet was conducted by high resolution CCD camera and ambient pressure(Pamb) and oxygen concentration(O2) was changed by control system. It was revealed that higher ambient pressure(Pamb), and oxygen concentration(O2) enhanced the soot generation and improved the maximum soot volume fraction(fv).

알케인계 단일 연료 액적의 Soot 생성 특성에 관한 실험적 연구

임영찬 ( Young Chan Lim ),서현규 ( Hyun Kyu Suh ) 한국액체미립화학회 2017 한국액체미립화학회지 Vol.22 No.2

The soot formation characteristics of various alkane-based single fuel droplets were studied in this work. Also, This study was performed to provide the database of the soot behavior and formation of alkane-based single fuel droplet. The experi-mental conditions were set to 1.0 atm of ambient pressure (P_amb), 21% of oxygen concentration (O₂) and 79% of nitrogen concentration (N₂). Combustion and soot formation of single fuel droplet was visualized by visualization system with high speed camera. At the same time, ambient pressure, oxygen concentration and nitrogen concentration were maintained by ambient condition control system. Soot formation characteristics was analyzed and compared on the basis of intensity ratio (I/I₀) of background image. The results of toluene fuel droplet showed the largest soot generation. Soot volume fraction (f_v) was almost the same under the identical fuel types regardless of various initial droplet diameter (d₀) since thermophoretic flux was not much changed under the same ambient conditions.

나노유체 : 초기 직경 변화에 따른 Toluene 액적의 연소 특성

임영찬 ( Young Chan Lim ),서현규 ( Hyun Kyu Suh ) 한국액체미립화학회 2015 한국액체미립화학회 학술강연회 논문집 Vol.2015 No.-

The main purpose of this study is to provide the information of soot generation of toluene fuel droplet. To achieve this, this paper provides the experimental results on the different initial diameter of toluene droplet combustion characteristics conducted under equivalent ambient pressure(P(amb)) and oxygen concentration(O2) conditions. Visualization of single fuel droplet was performed with high resolution CCD camera and visualization system. At the same time, ambient pressure(P(amb)) and oxygen concentration(O2) was maintained by ambient condition control system. Soot volume fraction(f(v)) was analyzed and compared on the basis of intensity ratio(I/I0) of background image. The result of soot generation was almost the same regardless of initial droplet diameter since thermophoretic flux is not much changed under the same ambient conditions. Soot standoff ratio(SSR) of 2mm diameter showed unstable variation characteristics due to the short available measuring time.

고온, 고압의 분위기 변화가 n-butanol 및 n-heptane 연료의 연소 특성에 미치는 영향

임영찬 ( Young Chan Lim ),서현규 ( Hyun Kyu Suh ) 한국분무공학회 2016 한국액체미립화학회지 Vol.21 No.1

The effect of high ambient temperature and pressure conditions on the combustion performance of n-butanol, n-heptane and its mixing fuel (BH 20) were studied in this work. To reveal this, the closed homogeneous reactor model applied and 1000-1200 K of the initial temperature, 20-30 atm of initial pressure and 1.0 of equivalence ratio were set to numerical analysis. It was found that the results of combustion temperature was increased and the ignition delay was decreased when the ambient conditions were elevated since the combustion reactivity increased at the high ambient conditions. On the contrary, under the low combustion temperature condition, the combustion pressure was more influenced by the ambient temperature in the same ambient conditions. In addition, the total mass and the mass density of tested fuels were influenced by the ambient pressure and temperature. Also, soot generation of mixing fuel was decreased than n-heptane fuel due to the oxygen content of n-butanol fuel.

n-heptane 연료 혼합비에 따른 n-butanol 연료의 연소 성능에 관한 해석적 연구

임영찬(Young Chan Lim),서현규(Hyun Kyu Suh) 한국연소학회 2015 KOSCOSYMPOSIUM논문집 Vol.2015 No.5

당량비 변화에 따른 바이오디젤 연소 및 CO, NO<SUB>X</SUB> 생성 특성 예측

임영찬(Young Chan Lim),서현규(Hyun Kyu Suh) 한국연소학회 2016 한국연소학회지 Vol.21 No.1

This study was performed to provide the basic information of the combustion, CO and NOX characteristics of biodiesel in accordance with equivalence ratio. The closed homogeneous reactor model used for the analysis. The analysis conditions were set to 900 K of the initial temperature, 20 atm of initial pressure and equivalence ratio was changes from 0.6 to 1.4. The results of analysis were predicted and compared in terms of combustion temperature, combustion pressure, CO and NOX emissions. The results of combustion characteristics showed that ignition delay was decreased and the combustion temperature and combustion pressure was increased in accordance with equivalence ratio. CO emission was decreased in lean condition(Φ< 1.0), however, CO emission was increased in rich condition(Φ> 1.0) because oxygen supply insufficient. NOX emission showed the largest amount in condition 0.8 of equivalence ratio because the oxygen concentration was sufficient.

단파장 필터링을 통한 연료 액적의 화염 거동 특성 분석

임영찬 ( Young Chan Lim ),정준우 ( Jun Woo Jung ),서현규 ( Hyun Kyu Suh ) 한국액체미립화학회 2018 한국액체미립화학회 학술강연회 논문집 Vol.2018 No.-

This experimental study was investigated to observe the flame behavior of biodiesel, diesel, and n-heptane fuel droplets in normal gravity condition. It will expect to provide basic information on the ignition delay, and flame propagation speed of these fuel droplets. In order to visualize the combustion process of test fuels, droplet combustion visualization and analysis were conducted using a high speed camera and the CCD camera. Single fuel droplet was formed on stainless wire using a syringe pump and was combusted using the power supply equipment. The ignition delay of n-heptane fuel droplet became shorter than those of biodiesel and diesel fuel droplets due to the lowest boiling point and volatility characteristics. In addition, the flame propagation speed was similar regardless of the initial droplet diameter(d0). However, the flame propagation speed of biodiesel droplet increased in the range from 1.428 mm to 1.542 mm of initial droplet diameter.