农业工程学报
農業工程學報
농업공정학보
2014年
15期
83-92
,共10页
尹必峰%王佳%何建光%徐毅%贾和坤
尹必峰%王佳%何建光%徐毅%賈和坤
윤필봉%왕가%하건광%서의%가화곤
柴油机%优化%燃烧%预混合低温燃烧%早喷射%废气再循环
柴油機%優化%燃燒%預混閤低溫燃燒%早噴射%廢氣再循環
시유궤%우화%연소%예혼합저온연소%조분사%폐기재순배
diesel engines%optimization%combustion%low-temperature premixed combustion%early injection%exhaust gas recirculation
为探索轻型车用柴油机在中小负荷率工况下实现超低排放的预混合低温燃烧策略，以某四缸轻型车用柴油机为样机，在中小负荷率工况下，进行了喷射正时、废气再循环率（exhaust gas recirculation，EGR）、进气温度、喷射压力、预喷射等不同控制参数对柴油机预混合低温燃烧影响的试验研究。证明适时早喷射可延长预混合期实现预混合燃烧，改善柴油机碳烟排放；采用高比例EGR技术降低进气氧浓度能有效控制预混合燃烧温度，可有效降低 NOx排放，同时可推迟由早喷射造成的过早的燃烧相位；在适时早喷射结合高比例 EGR 的基础上，协同优化喷射压力、进气温度与预喷射参数改善NOx和碳烟排放Trade-off关系，以实现超低排放的预混合低温燃烧；通过预混合低温燃烧路径优化后，10%、25%和50%负荷率工况NOx排放与原机相比分别降低97.8%、80.7%和62.1%，碳烟排放分别降低76%、93.9%和47.1%。3个负荷率工况下优化后的有效燃油消耗率比优化前略有上升。研究结果为轻型柴油机预混合低温燃烧过程的优化及污染物排放控制技术提供了理论基础。
為探索輕型車用柴油機在中小負荷率工況下實現超低排放的預混閤低溫燃燒策略，以某四缸輕型車用柴油機為樣機，在中小負荷率工況下，進行瞭噴射正時、廢氣再循環率（exhaust gas recirculation，EGR）、進氣溫度、噴射壓力、預噴射等不同控製參數對柴油機預混閤低溫燃燒影響的試驗研究。證明適時早噴射可延長預混閤期實現預混閤燃燒，改善柴油機碳煙排放；採用高比例EGR技術降低進氣氧濃度能有效控製預混閤燃燒溫度，可有效降低 NOx排放，同時可推遲由早噴射造成的過早的燃燒相位；在適時早噴射結閤高比例 EGR 的基礎上，協同優化噴射壓力、進氣溫度與預噴射參數改善NOx和碳煙排放Trade-off關繫，以實現超低排放的預混閤低溫燃燒；通過預混閤低溫燃燒路徑優化後，10%、25%和50%負荷率工況NOx排放與原機相比分彆降低97.8%、80.7%和62.1%，碳煙排放分彆降低76%、93.9%和47.1%。3箇負荷率工況下優化後的有效燃油消耗率比優化前略有上升。研究結果為輕型柴油機預混閤低溫燃燒過程的優化及汙染物排放控製技術提供瞭理論基礎。
위탐색경형차용시유궤재중소부하솔공황하실현초저배방적예혼합저온연소책략，이모사항경형차용시유궤위양궤，재중소부하솔공황하，진행료분사정시、폐기재순배솔（exhaust gas recirculation，EGR）、진기온도、분사압력、예분사등불동공제삼수대시유궤예혼합저온연소영향적시험연구。증명괄시조분사가연장예혼합기실현예혼합연소，개선시유궤탄연배방；채용고비례EGR기술강저진기양농도능유효공제예혼합연소온도，가유효강저 NOx배방，동시가추지유조분사조성적과조적연소상위；재괄시조분사결합고비례 EGR 적기출상，협동우화분사압력、진기온도여예분사삼수개선NOx화탄연배방Trade-off관계，이실현초저배방적예혼합저온연소；통과예혼합저온연소로경우화후，10%、25%화50%부하솔공황NOx배방여원궤상비분별강저97.8%、80.7%화62.1%，탄연배방분별강저76%、93.9%화47.1%。3개부하솔공황하우화후적유효연유소모솔비우화전략유상승。연구결과위경형시유궤예혼합저온연소과정적우화급오염물배방공제기술제공료이론기출。
The combustion process of diesel engines has a significant effect on the power, economy, and emission performance of a vehicle. As internal combustion engines tend to be highly effective, energy-saving, and environmentally friendly, all the scholars of the world in this area concentrate on creatively developing the combustion theories and techniques for the oncoming generation of engines in order to break through the emission limits of conventional diesel engines. Aiming at the difficulties of forming the homogeneous charge and organizing the combustion progress for the compact structure of light-duty vehicle diesel engines, the research in this paper was based upon advanced injection combined with high proportion cooling EGR to achieve the low-temperature premixed combustion. Taking advantage of a pressure information acquisition and performance bench test, the effects of fuel injection strategies and intake system parameters on the low-temperature premixed combustion process and pollutants emissions were studied systematically, which explores the effective ways for forming the homogeneous charge and controlling the low-temperature combustion progress so that the theoretical principle of low-temperature premixed combustion techniques for engineering application was built. Based on an in-cylinder pressure information acquisition and performance bench test, the effects of combustion control parameters such as injection timing, injection pressure, intake oxygen concentration, intake temperature, and pilot-injection on a low-temperature premixed combustion process and emission performance were studied. This revealed that taking the advanced injection strategy can prolong the ignition delay period, and improving the fuel-air mixture is the key to reducing the soot emission. Diminishing the intake oxygen concentration can control the temperature of premixed combustion effectively, restrain the production of the NOx emission, and put the ignition phase of a premixed combustion which is too early off, which is beneficial to improving the combustion efficiency and enhancing the fuel economy. Increasing the fuel injection pressure makes the NOx and soot emissions reduced in the low-temperature combustion mode when the load ratios are 10% and 25%, while it brings about the increment of the NOx emission and the decrement of the fuel efficiency in a moderate duty. In the low-temperature combustion mode, the combustion efficiency can be dramatically improved by decreasing the intake temperature and putting off the ignition phase, the in-cylinder temperature can be decreased, and the production of NOx is restrained at the same time. The soot emission can be reduced by raising the intake temperature appropriately when the load ratio is 10%, while intake cooling plays an important role in cutting the soot emission down at the load ratios of 25%and 50%.Multi-injection strategy is an effective method to extend the operating scope of low-temperature combustion and ameliorate the trade-off relationship between the NOx and soot emissions. Pilot injection can reduce the main injection amount, and shorten the ignition delay period of the main injection fuel. As a result, the exothermic phase advances and the peak value of the heat release rate descend so that the soot is successfully restrained. What’s more, different injection parameters have different effects on the soot emission. Compared with the original engine, the NOx emissions decreased by 97.8%, 80.7%and 62.1%respectively when the load rates were 10%, 25%, and 50%, and the soot emissions decreased by 76%, 93.9%, and 47.1%, while the brake specific fuel consumptions increased slightly.
