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수치해석을 이용한 DME HCCI 엔진의 열적성층화 효과에 대한 메커니즘 연구
오충환(Chunghwan Oh),나랑후 잠스란(Narankhuu Jamsran),임옥택(Ockteack Lim),정재훈(Jaehoon Jung) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
Homogeneous charge compression ignition(HCCI) engine has been attracted as the potential engine combustion process which has high efficiency and low-emission. However, there is one task to be solved. In the high-load range, the engine operating range is limited because of the knocking. To solve this problem, some studies to reduce the cause of rapid combustion have being progressed. In this study, some numerical analyses were conducted to analyze mechanisms on the thermal stratification effects. Under the condition of the 1 degree, the reaction timing of low-temperature oxidation and high-temperature oxidation according to variation of initial temperature was considered. Also, when the width of thermal stratification was varied, it considered that the change of lowtemperature oxidation and high-temperature oxidation.
수치해석을 이용한 DME HCCI 엔진의 열적성층화 효과에 대한 메커니즘 연구
오충환(Chunghwan Oh),나랑후 잠스란(Narankhuu Jamsran),임옥택(Ockteack Lim) 한국자동차공학회 2012 한국자동차공학회 지부 학술대회 논문집 Vol.2012 No.11
Homegeneous charge compression igrition(HCCI) engine has been attracted as the potential engine combustion process which has high efficiency and low-emission. However, there is one task to be solved. In the high-load range, the engine operating range is limited because of the knocking. To solve this problem, some studies to reduce the cause of rapid combustion have being progressed. In this study, some numerical analyses were conducted to analyze mechanisms on the thermal stratification effects. Under the condition of the I degree, the reaction timing of low-tempenture oxidation and high-temperature oxidation according to variation of initial temperature was considered. Also, when the width of thermal stratification was varied, it considered that the change of low-temperature oxidation and high-temperature oxidation.
HCCI엔진의 과급조건에서 EGR영향에 대한 수치해석적 연구
오충환(Chung Hwan Oh),나랑후 잠스란(Narankhuu Jamsran),임옥택(Ock Tack Lim) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.6
본 연구에서는 HCCI엔진의 과급조건에서 EGR의 영향에 대하여 수치해석적인 방법으로 연구하였다. 수치해석은 CHEMKIN-PRO에 있는 single-zone model을 사용하였고 연료로는 N-heptnae, Iso-octane 그리고 PRF50을 사용하였다. 사용된 연료의 화학반응 매커니즘과 열역학적 변수들은 Lawrence Livermore National Laboratory(LLNL)의 모델을 사용하였다. 연소상의 변화는 열효율에 큰 영향을 미치게 되므로 이영향을 배제하기 위해 본 연구에서는 CA50을 365oCA(5oCA aTDC)로 일정하게 고정하였다. 연구결과 EGR의 영향으로 줄어든 산소의 영향에 의해 저온산화반응과 NTC, 고온산화반응이 모두 약화되고 열발생률이 감소하는 것을 확인할 수 있었다. 과급과 EGR을 함께 사용하게 되면 과급에 의해 증가한 산소량과 연료의 영향으로 인해 연소가 강화되어 저온산화반응, NTC, 고온산화반응이 강화되고 열발생률이 증가하는 것을 확인할 수 있었다. EGR만을 사용하는 경우 IMEP가 감소하는 경향을 나타내지만 과급과 EGR을 함께 사용하는 경우 과급의 영향으로 인해 IMEP가 크게 증가하여 낮은 압력상승률과 높은 출력을 함께 얻을 수 있는 것을 확인하였다. This study used numerical methods to investigates investigate the exhaust gas recirculation (EGR) effect under the condition of boost pressure condition on a homogeneous charge compression ignition (HCCI) combustion engine using numerical methods. The detailed chemical-?kinetic mechanisms and thermodynamic parameters for n-heptane, iso-octane, and PRF50 from the Lawrence Livermore National Laboratory (LLNL) are were used for this study. The combustion phase affects the efficiency and power. To exclude these effects, this study decided to maintain a 50 burn point (CA50) at 5 CA after top dead center aTDC. The results showed that the EGR increased, but the low temperature heat release (LTHR), negative temperature coefficient (NTC), and high temperature heat release (HTHR) were weakened due by theto effect of the O2 reduction. The combined EGR and boost pressure enhanced the autoignition reactivity, . Hhence, the LTHR, NTC, and HTHR were enhanced, and the heat-release rate was increased. also In addition, EGR decraeased the indicated mean effective pressure ( IMEP), but the combined EGR and boost pressure increased the IMEP. As a results, combining the ed EGR and boost pressure was effective to at increase increasing the IMEP and maintaining the a low PRR .