커먼레일 직접분사식 디젤기관에서 바이오디젤유의 착화지연기간에 관한 연구 = A Study on the Ignition Delay Period of Biodiesel Fuel in Common-rail D.I. Diesel Engine

다국어 초록 (Multilingual Abstract)

Nowadays, diesel engine has been applied for high speed passenger cars and commercial vehicles as well as industrial parts widely. Because it has high efficiency, low fuel consumption, high endurance and exhaust of low CO2. However, diesel engine does not have enough time to mix air and fuel because of its combustion characteristic, injection of the fuel only into the compressed air. So, the exhaust of soot and Nox by this incomplete and sudden combustion is becoming serious environment problem in the whole world.
Biodiesel fuel can be used as an alternative fuel in diesel engine. It is easily produced from vegetable oil such as rapeseed, soybean, and palm oil. Using this biodiesel fuel which has oxygen about 11～15% can reduce noxious exhaust gas. And the CO2 exhausted after used can be retrieved in growing plant for production biodiesel fuel.
The object of this paper is to study ignition delay period and combustion process after ignition of biodiesel fuel on common-rail injection system on which it is possible to control injection pressure, rate, and timing regardless of engine rpm. The ignition delay period is defined as the time interval from fuel injection to detection of the first hot flame by photo sensor. Flame photos were taken by high speed camera to analyse combustion process after ignition.
Three kind of fuels with different mixing ratio was used ; a)20% biodiesel fuel, b)100% pure biodiesel fuel and c)conventional diesel fuel. In addition, the each fuel was injected to compare the difference not only by mixing ratio but also according to various injection conditions. Injection conditions are as follows ; a)80MPa and 100MPa injection Pressure and b)BTDC 18°CA and BTDC 15°CA injection timing.
The results of test are summarized as follows
1) The Ignition delay period of BDF100 is the shortest out of all the test conditions though it has the highest viscosity and surface tension. It is considered to be the effect of high cetane number.
2) As the result of injection pressure increase, Ignition delay period and its standard deviation of all fuels were decreased because of improved atomization.
3) As the result of injection timing delay by 3°CA, Ignition delay period of all fuels was a little bit decreased but its standard deviation was increased. The reason of increased standard deviation is considered to be localized ignition around fuel spray in cylinder, which was been higher temperature and pressure due to delayed injection timing.

목차 (Table of Contents)

• 목 차
• Abstract ⅰ
• 목 차 ⅲ
• List of Tables ⅴ
• List of Figures ⅴ
• 제 1 장 서론 1
• 1.1 연구 배경 및 내용 1
• 제 2 장 이론적 고찰 3
• 2.1 착화지연기간 3
• 2.2 바이오디젤유 4
• 2.3 커먼레일 직접분사식 디젤기관 6
• 2.3.1 커먼레일 연료분사 시스템의 개요 6
• 2.3.2 커먼레일 연료분사 시스템의 구조 7
• 2.3.3 커먼레일 연료분사 시스템의 장점 10
• 2.4 가시화 기관 11
• 2.4.1 가시화 기관의 개요 11
• 2.4.2 관찰창 12
• 2.5 P-V 선도 12
• 제 3 장 실험장치 및 실험방법 15
• 3.1 실험용 기관으로 개조 15
• 3.1.1 실린더 헤드 (cylinder head) 16
• 3.1.2 실린더 라이너 (cylinder liner) 17
• 3.1.3 연소실 형상 (combustion chamber type) 18
• 3.2 커먼레일 연료분사 시스템 19
• 3.3 착화지연기간의 설정 20
• 3.4 실험 방법 21
• 3.4.1 바이오디젤유의 혼합 21
• 3.4.2 착화지연기간의 측정 22
• 3.4.3 연소과정의 촬영 25
• 제 4 장 실험 결과 및 고찰 27
• 4.1 바이오디젤유의 착화지연기간 특성 28
• 4.1.1 바이오디젤유 함유량과 분사압력 변화에 따른
• 착화지연기간 특성 28
• 4.1.2 바이오디젤유 함유량과 분사시기 변화에 따른
• 착화지연기간 특성 31
• 4.2 바이오디젤유의 연소 특성 34
• 4.2.1 바이오디젤유 함유량과 분사압력 변화에 따른
• 연소 특성 34
• 4.2.2 바이오디젤유 함유량과 분사시기 변화에 따른
• 연소 특성 39
• 제 5 장 결론 43
• 참고문헌 45