가스연료의 벙커링을 위한 계량시스템의 표준화 연구

임옥택(Ocktaeck LIM),조원준(Wonjun CHO),김기동(Kidong KIM),모용기(Yonggi MO) 한국가스학회 2018 한국가스학회 학술대회논문집 Vol.2018 No.11

[일본] 혁신적 차세대 저공해차 종합기술개발 3 (차세대자동차의 종합 평가 기술개발) Clean Diesel Project 3

임옥택(Ocktaeck LIM) 한국자동차공학회 2011 오토저널 Vol.33 No.3

[일본] 2011년 상반기 일본 엔진기술 연구동향

임옥택(Ocktaeck LIM) 한국자동차공학회 2011 오토저널 Vol.33 No.11

예혼합기의 열적성층화가 PRF연료의 예혼합압축자기착화에 미치는 영향

임옥택(Ocktaeck LIM),이이다 노리마사(Norimasa IIDA) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The HCCI combustion mode poses its own set of narrow engine operating by knocking. In order to solve this, inhomogeneity method of mixture and temperature is suggested. The purpose of this research is to get fundamental knowledge about the effect of thermal stratification on HCCI combustion of PRF -Air mixture. The temperature stratification is made by buoyancy effect in combustion chamber of RCM. The analysis items are pressure, temperature of in-cylinder gas and combustion duration. In addition, the structure of flames using the two dimensional chemiluminescence's images by a framing camera are analyzed. Under stratification, the LTR starting time and the HTR starting time are advanced than that of homogeneous. Further, the LTR period of homogeneous conditions became shorter than that of the stratified conditions. With the case of homogeneous condition, the luminosity duration becomes shorter than the case of stratified condition. Additionally, under stratified condition, the brightest luminosity intensity is delayed longer than at homogeneous condition.

DME/n-Butane 혼합 연료의 농도 성층화에 의한 HCCI엔진연소의 압력 상승률 저감에 관한 연구

임옥택(Ocktaeck Lim),박규열(Kyuyeol Park) 한국가스학회 2011 한국가스학회지 Vol.15 No.3

본 연구에서는 DME와 n-Butane 연료를 사용하여 혼합연료 및 성층화효과가 HCCI 연소 특성에 미치는 영향을 화학반응수치계산을 통해서 알아보고자 한다. 우선, 기존에 완성된 DME와 n-Butane 반응스킴을 이용하여 새로운 화학 반응 모델을 만들고 기존의 DME 화학 반응 모델과 n-Butane 화학 반응 모델과 비교하여 유효성을 확보한다. 나아가, 자발화 특성이 다른 DME와 n-Butane 두 연료의 혼합비 변화에 따른 HCCI 연소 특성을 파악한다. 마지막으로, 혼합 연료를 각각 성층급기 했을 경우에 압력상승률 저감 효과를 파악 한다. This study investigates the effects of the DME and n-Butane mixture and of the stratification on combustion characteristics of HCCI engine by chemical reaction calculation. First, the existing DME reaction scheme and n-Butane is combined to make new chemical reaction model, then validating the effectiveness of new scheme. Furthermore, this study verify the HCCI combustion characteristics according to the changes of DME and n-Butane mixture ratio, which shows different auto ignition characteristics. Finally, it confirms the effects of stratification of mixture fuel on the reduction of pressure rise rate.

열적성층화가 DME/n-Butane 예혼합압축자기착화연소에 미치는 영향에 관한 연구

임옥택(Ocktaeck Lim) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.12

HCCI 엔진연소에서 열적성층화 효과는 노킹을 회피하는 수단으로서 생각되고 있다. 본 연구에서는 DME 와 n-Butane 을 연료로 하는 HCCI 엔진연소의 열적성층화 효과를 조사하였다. 예혼합기가 연소실내부에 투입되고 부력의 효과를 이용하여 연소실 내부에 열적성층화를 형성한다. 그 뒤에 피스톤의 압축에 의해서 단열압축 시킨 후 연소실압력과 2 차원화학발광법을 계측하여 해석하였다. 열적성층화가 존재하는 경우에는, 저온산화반응과 고온산화반응의 시작시기가 균질한 경우에 비해서 진각되었고 연소기간은 길어졌다. 발광의 시작은 온도가 높은 곳에서부터 시작하여 온도가 낮은 곳으로 전파 되는 것을 확인하였고 발광기간도 길어짐을 확인하였다. The thermal stratification effect has been thought as one of the way to avoid dramatically generating the heat from HCCI combustion. We investigate the effect of thermal stratification on HCCI combustion fueled by DME and n-Butane. The thermal stratification occurs in a combustion chamber of a rapid compression machine with premixture by buoyancy effect that is made of fuel and air. The premixture is then adiabatically compressed, and during the process, the in-cylinder gas pressure is measured and two-dimensional chemiluminescence images are prepared and analyzed. Under the thermal stratification, the LTR starting time and the HTR starting time are advanced than that of homogeneous case. Further, the LTR period and the luminosity duration under homogeneous conditions are shorter than the corresponding quantities under stratified conditions. Additionally, under stratified conditions, the brightest luminosity intensity is delayed longer than that of homogeneous condition.

화학반응수치해석을 이용한 HCCI기관의 예혼합기의 성층화성이 연소시의 압력 상승률에 미치는 영향

임옥택(Ocktaeck LIM),박규열(Kyuyoel Park),백영순(Youngsoon Baek),표영덕(Youngduk Pyo) 한국가스학회 2009 한국가스학회 학술대회논문집 Vol.2009 No.4

The HCCI engine is prospective internal combustion engine, which is capable of providing both high diesel-like efficiencies and very low NOx and particulate emissions. However, several technical issues must be resolved before an HCCI engine can be used as widespread application. One of issues is that its operating range is limited by an excessive pressure rise rate which is caused by excessive heat release because of its self-accelerated combustion reaction and the resulting engine knock in high-load region. The purpose of this study is to evaluate the potential of thermal and fuel stratification for reducing pressure rise rate in an HCCI engine. The concentration of NOx and CO in exhaust gas is also evaluated to confirm the combustion completeness and NOx emission. The computational work is conducted using a multi-zone code with detailed chemical kinetics, including the effects of thermal and fuel stratification on the onset of ignition and the rate of combustion.

HCCI엔진연소에서 엔진회전수의 영향에 대한 수치해석연구

임옥택(Ocktaeck Lim),윤상진(Sangjin Yoon),박규열(Kyuyeol Park) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5

HCCI combustion offers both high efficiencies and very low NOX and particulate emissions. However, operating range of HCCI engines is limited by an excessive pressure rise rate(PRR) during combustion in high load region which will lead engine knock. HCCI combustion is controlled by chemical reaction depending on thermal properties and fuel composition. Besides, engine speed also has significant effects on ignition timing, since it relates to the speed of compression. The engine speed is related to combustion robustness in expansion stroke because of changing expansion speed. The objective of this study is to investigate the influence of engine speed on combustion characteristics such as in-cylinder gas temperature, pressure at combustion start, combustion duration and combustion efficiency by using numerical analysis. Then, In order to investigate the mechanism of influence of engine speed, contribution matrix has been used. In results, DME which has negative temperature coefficient and methane which has not negative temperature coefficient were used as fuels.

DME/Diesel 듀얼 퓨얼 엔진의 연소 및 배출특성에 관한 연구

임옥택(Ocktaeck Lim),박규열(Kyuyeol Park),표영덕(Youngduck Pyo),이영재(Youngjae Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

Nowadays we are more concerned about emissions that are harmful in our environment, so at once an increasing of importance to think about clean diesel. One of the alternative technologies covers in this study that is preceded by dual-fuel combustion which is controlling combustion by using two fuels with different auto-ignition values. For dual-fuel combustion, here used two fuels such as DME and diesel. Both of them have different characteristics of evaporation and auto-Ignition. In the current work, we focus on understanding the characteristic of combustion and emissions under single cylinder engine and ignition is done by compression ignition. Pre-mixture is formed by injecting low-pressure DME into an intake manifold and high-pressure fuel (diesel or DME) is injected directly into the cylinder. Both direct diesel injection and port fuel injection reduced the significant amount of Soot, CO and NOx in the homogeneous charge compression ignition engine due to present of oxygen in DME as well having diesel engine like thermal efficiency. In addition, when direct DME injecting in cylinder with port DME injection, there is no changes in emissions and energy consumption rate even causing homogeneous charge compression ignition.

EGR 율이 DME HCCI 엔진연소과정에 미치는 영향에 관한 연구

임옥택(Ocktaeck LIM) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.10

본 연구에서는 고농도 EGR 을 사용하는 DME 예혼합압축자기착화연소의 근본적인 연소메커니즘을 이해하기 위해 수치해석 시뮬레이션을 수행하였다. EGR 과 과급의 영향을 조사하면서 동시에 산소 분압과 산소 농도 중 어느 것이 LTR 발열비율을 결정하는 핵심요소인지 확인하였다. EGR 비율과 과급압력을 매개변수 정하기 위해서 1) EGR 비율변화에 따라 산소농도, 산소함유량을 변화시키는 조건 2) 산소농도를 거의 일정하게 유지하면서 과급을 하여 산소 분압을 변화시키는 조건, 3) EGR 과 과급을 조합하면서 산소 분압을 일정하게 유지 하기 위해 산소농도를 변화시키는 조건 세가지 조건에서 화학반응수치계산을 수행하여 검증했다. 연구결과 EGR 율이 증가하면 연소의 시작, 종료시기가 지연되고, 과급을 하게 되면 연소의 시작, 종료시기가 앞당겨지는 것을 확인했다. EGR 과 과급이 LTHR 발열비율 증가에 영향을 미치는 것도 확인하였다. This study aims to provide helpful suggestions for understanding the effect of high EGR on DME HCCI combustion. This study determined which between oxygen partial pressure and oxygen concentration was the main factor affecting the LTHR heating ratio. Furthermore, EGR and the supercharging effect were investigated. To define the parameters for the EGR ratio and supercharging pressure, a numerical analysis of the chemical reaction was conducted under the following conditions: (1) variation of EGR ratio, oxygen concentration, and oxygen content; (2) variation of oxygen partial pressure while the oxygen concentration was almost constant; and (3) variation of oxygen concentration while oxygen partial pressure was constant with EGR and supercharging. The results show that an increase in EGR reduces the combustion duration. On the other hand, an increase in boost pressure increases the combustion duration. Finally, the EGR and boost pressure affect the amount of increase in LTHR.