Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
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Effects of Fuel Blending Ratio and Oxygen Concentration on Auto-ignition Characteristics of n-Decane/Ethanol Blended Fuels

연료 혼합비율 및 산소농도가 노말데케인/에탄올 혼합연료의 점화특성에 미치는 영향

  • Oh, Chae Ho (School of Mechanical Engineering, Pusan Nat'l Univ.) ;
  • Kang, Ki Joong (School of Mechanical Engineering, Pusan Nat'l Univ.) ;
  • Choi, Gyung Min (School of Mechanical Engineering, Pusan Nat'l Univ.)
  • Received : 2017.06.16
  • Accepted : 2017.08.09
  • Published : 2017.11.01
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Abstract

To cope with the development of alternative fuels and international environmental regulations, this study provides a numerical analysis of the effects of composition and temperature changes of n-decane and ethanol on auto-ignition characteristics. CHEMKIN-PRO is used as the analysis program and the LLNL model is used as the reaction model. The numerical results show that the ignition delay time increases as the mole fraction of ethanol increases for temperatures below 1000 K, where low temperature reactions occur. Because of the high octane number of ethanol, the high percentage of ethanol delays the increase in the concentration of OH radicals that cause ignition. The oxygen concentration in the mixture is changed to apply the exhaust gas recirculation and a numerical analysis is then performed. As the oxygen concentration decreases, the total ignition delay time increases because the nitrogen gas acts as a thermal load in the combustion chamber.

본 연구는 대체연료 개발 및 국제환경규제에 대응하기 위하여, 노말데케인과 에탄올 혼합연료의 조성 및 온도 변화가 자착화 특성에 미치는 영향을 수치적으로 해석하였다. 해석용 프로그램으로는 CHEMKIN-PRO를 사용하였고, 반응모델은 LLNL모델을 이용하였다. 수치해석 결과를 통해 저온 연소 반응이 일어나는 1000K 이하에서는 에탄올의 몰 비율이 증가함에 따라 점화지연 시간이 증가하는 현상을 확인하였다. 에탄올의 높은 옥탄가로 인해 에탄올의 높은 비율은 점화를 일으키는 OH라디칼의 농도 증가를 지연시키기 때문이다. 배기가스 재순환을 적용하기 위해 혼합연료에 산소농도를 변화하여 수치해석을 하였다. 산소농도가 감소함에 따라 전체 점화지연시간은 증가하게 되고, 이는 질소가스가 연소실 내에 열부하로 작용하기 때문이다.

Keywords

References

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