进气门晚关米勒循环对高强化柴油机燃烧和换气影响的研究
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摘要
为了探索米勒循环技术对于燃烧和换气过程的影响,在1台高强化单缸柴油机上应用进气门晚关米勒循环进行了试验和仿真研究。进气门关闭时刻分别为上止点后-110°CA(原机)、-86°CA和-70°CA.发动机试验在转速3 600 r/min、指示升功率77 k W/L、过量空气系数1. 6的高强化运行工况下展开。通过对试验平台建立一维热力学计算模型进一步分析了米勒进气相位对换气过程参数的影响。研究结果表明:随着进气门关闭时刻的推迟,由于有效压缩比的降低,缸内压缩终了工质温度和压力均显著下降,在相同功率条件下最大燃烧压力和温度、最大压力升高率、排气温度均显著下降,有助于降低高强化柴油机缸内的热力负荷;随着进气门关闭时刻的推迟,压缩过程中的米勒损失和进气回流率增加,充量系数、泵气损失均下降;进气门晚关的米勒循环还明显降低了NO_x排放,改善了燃油消耗率。
The effect of Miller cycle with late intake valve closing( LIVC) timings on the combustion and gas exchange of a highly intensified single-cylinder diesel engine is studied through experiment and simulation. Three LIVC timings,i. e.,-110°CA( original engine),-86°CA and-70°CA after top dead center,are used in the research. The engine test is conducted under the operating conditions: a speed of3 600 r/min,an indicated power density of 77 kW and an excess air ratio of 1. 6. An 1-D thermodynamic simulation model is established for the engine test setup in order to further analyze the influence of LIVC Miller cycle on the gas exchange process. The results show that,as the intake valve closure( IVC) timing retards,the in-cylinder charge pressure and temperature are reduced obviously due to the reduction in the effective compression ratio. This results in a noticeable decrease in the maximum combustion pressure and temperature,the maximum pressure rise rate and the exhaust temperature. This means that LIVCMiller cycle helps to constrain the increasing mechanical and thermal loads in the highly intensified diesel engine. In addition,as the IVC timing retards,the Miller loss and backflow rate during the compression stroke increase,while the charging coefficient and pumping loss decrease. The LIVC Miller cycle is also benefit to improve fuel consumption and reduce NO_x emissions.
The effect of Miller cycle with late intake valve closing( LIVC) timings on the combustion and gas exchange of a highly intensified single-cylinder diesel engine is studied through experiment and simulation. Three LIVC timings,i. e.,-110°CA( original engine),-86°CA and-70°CA after top dead center,are used in the research. The engine test is conducted under the operating conditions: a speed of3 600 r/min,an indicated power density of 77 kW and an excess air ratio of 1. 6. An 1-D thermodynamic simulation model is established for the engine test setup in order to further analyze the influence of LIVC Miller cycle on the gas exchange process. The results show that,as the intake valve closure( IVC) timing retards,the in-cylinder charge pressure and temperature are reduced obviously due to the reduction in the effective compression ratio. This results in a noticeable decrease in the maximum combustion pressure and temperature,the maximum pressure rise rate and the exhaust temperature. This means that LIVCMiller cycle helps to constrain the increasing mechanical and thermal loads in the highly intensified diesel engine. In addition,as the IVC timing retards,the Miller loss and backflow rate during the compression stroke increase,while the charging coefficient and pumping loss decrease. The LIVC Miller cycle is also benefit to improve fuel consumption and reduce NO_x emissions.
引文
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[13]徐敏,桂勇,孙佑成,等.米勒循环拓展均质压燃燃烧负荷范围的计算[J].内燃机学报,2013,31(1):15-21.XU M,GUI Y,SUN Y C,et al. Computation on load extension of HCCI combustion using Miller cycle[J]. Transactions of CSICE,2013,31(1):15-21.(in Chinese)
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[17] KOVACS D,EILTS P. Potentials of the Miller cycle on HD diesel engines regarding performance increase and reduction of emissions[C]∥Proceedings of the SAENA 12th International Conference on Engines&Vehicles. Napoli,Italy:SAE International,2015.
[18]张克诚,周作民.高速高增压研究用单缸机和燃烧过程的试验研究[J].兵工学报(坦克装甲车与发动机分册),1982,1(4):19-29.ZHANG K C,ZHOU Z M. Experimental investigation of high speed high-turbocharged single cylinder diesel engine and its combustion process[J]. Acta Armamentarii(Tanks,Armoured Vehicles and Engines),1982,1(4):19-29.(in Chinese)
[19]何学良.增压柴油机的单缸模拟试验[J].内燃机工程,1980,1(3):1-17.HE X L. Simulated experiment of turbocharged diesel engine by a single cylinder engine[J]. Chinese Internal Combustion Engine Engineering,1980,1(3):1-17.(in Chinese)
[2] STEINPARZER F,NEFISCHER P,HIEMESCH D,et al. The new BMW six-cylinder top engine with innovative turbocharging concept[J]. Motortechnische Zeitschrift,2016,77(10):38-44.
[3] HEIDUK T,WEIβU,FROHLICH A,et al. The new V8 TDI engine from Audi,part 1:engine architecture and turbocharging concept with electric powered compressor[J]. Motortechnische Zeitschrift,2016,77(6):20-25.
[4] EICHLER F,DEMMELBAUER-EBNER W,STROBEL J,et al.The new W12-TSI engine of the Volkswagen group[J]. Motortechnische Zeitschrift,2016,77(2):16-23.
[5] LAMPING M,KORFER T,WIX K. HSDI diesel engines-FEV's high power density concepts[J]. ATZ Autotechnology,2006,9(1):40-45.
[6] BLASIO G D,BEATRICE C,BEGIORNO G,et al. Functional requirements to exceed the 100 kW/L milestone for high power density automotive diesel engines[J]. SAE International Journal of Engines,2017,10(5):2342-2353.
[7] DEMARK R,GRODDECK M,RUETZ G. The new diesel engines series 890 by MTU[J]. Motortechnische Zeitschrift Worldwide,2006,67(2):2-5.
[8] ZHANG Y,WANG Z Y,BAI H L,et al. The reduction of mechanical and thermal loads in a high speed HD diesel engine using Miller cycle with late intake valve closing[C]∥Proceedings of SAE 2017 World Congress. Detroit,MI,US:SAE International,2017.
[9] TAYLOR J,FRASER N,DINGELSTADT R,et al. Benefits of late intake valve timing strategies afforded through the use of intake cam in cam applied to a gasoline turbocharged downsized engine[C]∥2011 SAE World Congress. Detroit,MI,US:SAE International,2011.
[10] EHLESKOG M,GJIRJA S,DENBRATT I,et al. Effects of variable inlet valve timing and swirl ratio on combustion and emissions in a heavy duty diesel engine[C]∥Proceedings of 2012 SAE World Congress. Detroit,MI,US:SAE International,2012.
[11] THEIβL H,KRAXNER T,SEITZ H,et al. Miller valve timing for future commercial diesel engines[J]. Motortechnische Zeitschrift,2015,76(11):4-11.
[12]刘二喜,战强,邬斌杨,等.进气门晚关与两次喷射协同作用对柴油机中转速中等负荷的影响[J].内燃机学报,2014,32(6):481-488.LIU E X,ZHAN Q,WU B Y,et al. Effect of late intake valve closing and split fuel injection on thermal efficiency and emissions of a heavy duty diesel engine at middle loads and middle speeds[J]. Transactions of CSICE,2014,32(6):481-488.(in Chinese)
[13]徐敏,桂勇,孙佑成,等.米勒循环拓展均质压燃燃烧负荷范围的计算[J].内燃机学报,2013,31(1):15-21.XU M,GUI Y,SUN Y C,et al. Computation on load extension of HCCI combustion using Miller cycle[J]. Transactions of CSICE,2013,31(1):15-21.(in Chinese)
[14]魏胜利,刘鑫,冷先银,等.进气门晚关米勒循环对柴油机燃烧和排放影响的研究[J].兵工学报,2015,36(8):1384-1390.WEI S L,LIU X,LENG X Y,et al. Research on effect of late intake valve closing Miller cycle on combustion and emissions of diesel engine[J]. Acta Armamentarii,2015,36(8):1384-1390.(in Chinese)
[15] NEVIN R M,SUN Y,GONZALEZ D,et al. PCCI investigation using variable intake valve closing in a heavy duty diesel engine[C]∥Proceedings of 2007 SAE World Congress. Detroit,MI,US:SAE International,2007.
[16] MILLO F,MALLAMO F,MEGO G. The potential of dual stage turbocharging and Miller cycle for HD diesel engines[C]∥Proceedings of 2005 SAE World Congress. Detroit,MI,US:SAE International,2005.
[17] KOVACS D,EILTS P. Potentials of the Miller cycle on HD diesel engines regarding performance increase and reduction of emissions[C]∥Proceedings of the SAENA 12th International Conference on Engines&Vehicles. Napoli,Italy:SAE International,2015.
[18]张克诚,周作民.高速高增压研究用单缸机和燃烧过程的试验研究[J].兵工学报(坦克装甲车与发动机分册),1982,1(4):19-29.ZHANG K C,ZHOU Z M. Experimental investigation of high speed high-turbocharged single cylinder diesel engine and its combustion process[J]. Acta Armamentarii(Tanks,Armoured Vehicles and Engines),1982,1(4):19-29.(in Chinese)
[19]何学良.增压柴油机的单缸模拟试验[J].内燃机工程,1980,1(3):1-17.HE X L. Simulated experiment of turbocharged diesel engine by a single cylinder engine[J]. Chinese Internal Combustion Engine Engineering,1980,1(3):1-17.(in Chinese)