2단분사조건에서 파일럿 분사량이 바이오디젤 연료의 연소 및 배기 배출물 특성에 미치는 영향

이형민 한국마린엔지니어링학회 2019 한국마린엔지니어링학회지 Vol.43 No.7

The purpose of this research is to analyze the influence of pilot injection quantity on the combustion and exhaust emission characteristics of biodiesel fuel under two-stage injection conditions: pilot injection and main injection. The combustion visualization test of the main injection was also carried out on the amount of the pilot injection. Analysis of the combustion and exhaust emission characteristics of biodiesel fuel according to the pilot injection quantity and combustion visualization was performed in a common rail single cylinder diesel engine, which can be visualized. The total injection quantity of biodiesel fuel was 10 mg/stroke, and the main injection amount was adjusted according to pilot injection quantity. The increase in pilot injection quantity caused a cylinder wall surface or piston wall wetting increment, thereby reducing the combustion performance of the main injection. As a result, the in-cylinder pressure, rate of heat release, indicated mean effect pressure, and torque decreased. As the pilot injection amount increased, carbon monoxide and hydrocarbons tended to increase while nitrogen oxides decreased. As the pilot injection quantity increased through combustion visualization, the ignition delay period during the main injection became shorter and appears to be similar to diffusion combustion rather than premixed combustion in the initial combustion. 본 연구의 목적은 파일럿 분사와 주 분사로 이루어지는 2단분사조건에서 파일럿 분사량이 바이오디젤 연료의 연소및 배기 배출물 특성에 미치는 영향을 분석하는 것이다. 또한, 파일럿 분사량에 따라 주 분사의 연소 가시화 시험도 수행되었다. 파일럿 분사량에 따라 바이오디젤 연료의 연소 및 배기 배출물 특성 분석, 연소 가시화는 가시화가 가능한 커먼레일단기통 디젤엔진에서 수행되었다. 바이오디젤 연료의 총 분사량은 10mg/stroke이며, 파일럿 분사량에 따라 주 분사량도 조절되었다. 파일럿 분사량이 증가할수록 실린더 벽면 또는 피스톤 적심을 증가시킬 뿐만 아니라 주 분사의 연소 성능을 저감시켜 실린더 내부 압력, 열발생율, 도시평균유효압력 및 토크가 떨어지는 결과를 보였다. 파일럿 분사량이 증가할수록 일산화탄소 및 탄화수소는 증가한 반면, 질소산화물은 감소하는 결과로 나타났다. 연소가시화를 통해 파일럿 분사량이 증가할수록 주 분사 시 점화지연기간은 짧아지며, 초기 연소 시 예혼합 연소 보다는 확산연소에 가까운 형태로 나타났다.

저온디젤연소에서 파일럿 분사가 연소특성에 미치는 영향

김기현(Kihyun Kim),한상욱(Sangwook Han),배충식(Choongsik Bae) 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.42

This experimental study investigated the effect of pilot injection on combustion characteristics ; specifically combustion noise and soot emission in the low temperature diesel combustion. Preliminary experiments under wide range of exhaust gas recirculation rate and injection timing were performed to find experimental condition which shows near zero nitrogen oxides emission and maximum indicated mean effective pressure. In the pilot injection experiment, pilot injection ratio and timing were varied. with fixed pilot injection quantity, more retarded pilot injection timing caused vigorous heat release prior to start of the main injection. It accelerated combustion start of the fuel injected at main injection timing while decreased peak of heat release rate. Soot emission was increased as pilot injection quantity and timing was increased and retarded, respectively. Maximum pressure rise rate was decreased when the small pilot injection quantity was injected. However, when pilot injection quantity and timing were increased and retarded respectively, maximum pressure rise rate increased even higher than single injection case.

직접분사식 압축착화엔진에서 Pilot분사에 따른 Diesel-DME 혼합연료의 연소 및 배기특성에 관한 연구

정재훈(Jaehoon Jeong),임옥택(Ocktaeck Lim) 한국자동차공학회 2014 한국 자동차공학회논문집 Vol.22 No.4

This work was investigated on pilot injection strategy of blended fuels(Diesel-DME) for combustion and emissions in a single cylinder direct injection compression ignition engine. Diesel and DME were blended by the method of weight ratio. Weight ratios for diesel and DME were 95:05 and 90:10 respectively. dSOI between main and pilot injection timing was varied. A total amount of injected fuels(single injection) was adjusted to obtain the fixed BMEP as 4.2 bar in order to compare with the fuel conditions. Also, the amount of pilot injection fuel was varied by 5%, 10% and 20% of total injection fuel. The engine was equipped with common rail and injection pressure is 700 bar at 1200 rpm. As a result, when mixing ratio increase, indicated thermal efficiency was increased in comparison with DD 100 and CO, THC and smoke were lower than DD 100. The influence of reducing NOx by pilot injection was more effective than DD 100. When pilot injection quantity increase, abrupt increase of NOx was occured at pilot injection quantity of 20%.

DME 직접분사식 압축착화 엔진에서 파일럿 분사의 영향

윤현숙(Hyeonsook Yoon),배충식(Chongsik Bae) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The dimethyl-ether (DME) combustion with pilot injection was investigated in a single cylinder direct injection diesel engine equipped with the common-rail injection system. Combustion performance and emissions were tested with dimethyl-ether. The main injection timing was at the top dead center, which were the best timings for maximum power output. The total injected fuel mass was fixed 22㎣ per cycle at 800 rpm. The fuel quantity and the injection timing of the pilot injection were varied from 8 to 20% of the total injected mass and from 50 to 10 crank angle degree before the main injection timing, respectively. The ignition delay decreased with the pilot injection. The indicated mean effective pressure increased when dimethyl-ether was pilot-injected at 20 crank angle degree before the main injection timing. DME showed reduction in emissions, such as particulate, hydrocarbon, carbon monoxide and nitric oxides. The hydrocarbon and the carbon monoxide emissions were increased when the pilot injection timing was advanced. The nitric oxide emission was increased by 14% with 8% of pilot injection. Bigger amount of DME pilot-injection decreased nitric oxide emission.

승용 디젤 CRDI 엔진의 다단 분사 및 분사압력이 연소 및 배기 특성에 미치는 영향

노현구(Hyungu Roh),전학식(Haksik Jeon),이창식(Changsik Lee) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

This paper describes the effect of the multiple injection and injection pressure on the combustion and emission characteristics in a CRDI diesel engine at various operating conditions. In order to investigate the influence of multiple injections and injection pressure in a diesel engine, the fuel injection timing was varied double pilot injections and main injection at TDC. The experimental apparatus is consisted of DI diesel engine with 4 cylinders, EC dynamometer, multi-stage injection and injection pressure control system, and exhaust emissions analyzer. The combustion and emission characteristics are investigated of various injection strategies such as analyzed for the main, one pilot-main, double pilot-main strategy. The results showed that the average of peak combustion pressure is increased with the increase of injection pressure. Also, double pilot injection has a great effect on reducing NOx emissions because the decrease of peak heat release rates. However soot is increased at the double pilot injection compared to single injection. Based on this result, it showed that the combustion and emission characteristics can be improved as the pilot injection is retarded.

승용 디젤 CRDI 엔진의 다단 분사가 연소 및 배기 특성에 미치는 영향

노현구(Hyun Gu Roh),이창식(Chang Sik Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

This paper described the effect of the multiple injection on the stability of idle-operating and emission characteristics in a common rail direct injection diesel engine at various operating conditions. In order to investigate the influence of multiple injections in a diesel engine, the fuel injection timing was varied two pilot injections and one main injection at various conditions. The experimental apparatus is consisted of DI diesel engine with 4 cylinders, EC dynamometer, multi-stage injection control system, and exhaust emissions analyzer. The combustion pressure was measured using a piezoelectric pressure sensor installed the hole of glow plug. Detection of the crank angle of rotating engine was used for the crankshaft position sensor of the magnetic inductive type installed. The exhaust emissions from the engine were measured by using transmitted light type soot measuring instrument and NOx, HC and CO analyzer. The operating point was analyzed for the main, pilot-main, pilot-pilot-main strategy were tested. It is revealed that the combustion pressure was smoothly near the TDC and the coefficient of variations is reduced due to the effect of pilot injection. Also, NOx emissions are dramatically decreased with pilot injection because the rate of heat release. However Soot is increased at early pilot injection at main injection.

Comparison of the effects of multiple injection strategy on the emissions between moderate and heavy EGR rate conditions: part 1-pilot injections

Jeongwoo Lee,Kookeui Hong,최승목,Seongeun Yu,최회명,민경덕 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.4

As vehicle emissions regulations have become stricter, improving injection strategies and using high EGR rates has become important to reduce engine-out emissions. Previous research has found that, a multiple injection strategy with a pilot or post injection has the potential to improve the distribution of the air-fuel mixture or oxidation. Thus, it is important to determine the effect of multiple injection strategies on the engine-out emissions. Especially, since the latest diesel engines have used high EGR rates to reduce NOx emission, the target of emissions is different from that of moderate EGR rate condition. Under heavy EGR rate condition, it is needed to improve combustion efficiency by reduction of CO and THC emissions. Therefore, in the first research as part 1, the effects of pilot injection on the engine-out emissions were systemically evaluated for two different EGR rate conditions (30 % and 60 %). The characteristics of the pilot injection were different between the two EGR rate conditions because the behavior of diesel combustion is significantly different when the EGR rate is changed. This research condition was investigated using varying injection parameters such as the timing and quantity of the pilot injection. The results show that each different pilot injection strategy was suggested between two EGR rate conditions to reduce engine-out emissions. Under moderate EGR rate condition, very earlier pilot SOI with large amount has the potential to reduce NOx and PM emissions simultaneously. On the other hand, under heavy EGR rate condition, the closest pilot SOI to main SOI has the potential to reduce CO and THC emissions.

다단분사를 사용한 경량 DME 엔진의 연소제어에 관한 연구

정수진(Soo-Jin Jeong),오세두(Se-Doo Oh),박정권(Jeong-Kwon Park) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5

Dimethyl-ether(DME) is one of the most promising alternative fuels for IC engines. In this study, the compression ignition combustion fueled with dimethyl-ether was investigated. Three-point split injection strategy was applied and evaluated its availability and performance in terms of emission(CO, HC, NOx, PM), fuel economy and power. Experiments were carried out in 4-cylinder 2.9 liter direct-injection diesel engine equipped with common-rail injection system, and the engine performance and emission characteristics were tested the various pre and pilot injection timings and quantities. Experiments were performed under the engine condition ranging from 1200rpm, 2bar to 3000rpm,4 bar. From the results of this study, three-point split injection strategy showed the possibility to overcome the disadvantages of DME engine such as high NOx and HC emissions due to long injection duration for attaining diesel equilibrium performance. By optimizing pre and pilot injection timing and quantities NOx emission could be reduced by maximum 68.5% for low speed and load conditions. Additional NOx reduction of could be obtain by retarding main injection timing. Torque could be improved by reducing injection dwell timing between pilot and main injection. In the range of medium and high load and speed conditions, main injection timing was retarded for reducing NOx emission with sacrificing torque. However, this torque reduction could be compensated by reducing pilot injection quantity and increasing the quantity of main injection.

선박용 디젤 엔진에서 Pilot 분사에 대한 연소 특성 연구

이병화(Byounghwa Lee),배명직(Myungjik Bae),한동식(Dongsik Han),전충환(Chunghwan Jeon),장영준(Youngjune Chang),송주헌(Juhun Song) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

Multidimensional simulation has been carried out to be clear the role of initial combustion in a marine diesel engines on reduction of NOx and soot emissions by different pilot injection condition. Pilot injection can shorten the ignition delay, thus it reduces the premixed combustion phase. Since most NOx is formed during premixed combustion, pilot injections is one of reliable strategies to reduce the NOx. The formation of NOx consists of that formed by pilot injection and that formed by main injection. The result explains that 25-3-75 among the pilot injection conditions is effective to reduce the NOx, due to optimal combination pilot injection with main injection. The purpose of this study is to explain the characteristics of combustion with pilot injection of the marine diesel engine on reduction of exhaust emissions by examining the combustion process in a cylinder and to explore the formation mechanism of NOx between pilot injection and main injection.

Correction strategy of fuel injection quantity during pilot-main injection for common rail system

Yun Bai,Yuanqi Gu,Qi Lan,Liyun Fan,Xiuzhen Ma 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6

Common rail system is a key technology of energy saving and emission reduction for modern diesel engines. Multiple injection, as one of the most interesting features of common rail system, allows both optimal fuel consumption and exhaust emissions. In order to explore the method for controlling the fluctuation of fuel injection quantity during multiple injection, experiments have been carried out in this paper, focusing on pilot-main injection. The high pressure fuel circuits of the system have been equivalent to a spring-mass vibration system. Comparison with the experiment shows that the proposed fluctuation equation can reasonably predict the fluctuation characteristics of main injection quantity with pilot-main injection interval. The correction control strategy for the main injection quantity fluctuation has been proposed, in which the relative damping coefficient, rail pressure, pilot-main injection interval and main injection pulse width are chosen as the input variables. The experimental results with different rail pressure and main injection quantity show that the fluctuation of injection quantity during pilotmain injection can be controlled effectively by the proposed correction strategy. The maximum average fluctuation of main injection quantity decreases by as much as 44.66 %.