Analysis of lean combustion and emission characteristics of Miller cycle gasoline engine

doi:10.3969/j.issn.1674-8484.2021.03.016

Abstract

Abstract:

The influence factors of lean burn process on combustion and emission of supercharged Miller cycle direct injection gasoline engine was experimentally investigated, in which the influence law of lean burn combined with exhaust gas recirculation (EGR) on fuel consumption rate of gasoline engine was analyzed, and the cylinder lean burn process was visually analyzed with a transparent engine. The results show that the fuel consumption rate decreases by about 7% when the excess air coefficient (λ) is 1.55 and the fuel consumption rate increases inversely with increasing λ; Lean burn leads to strong Miller effect and the expansion ability of air-fuel ratio is limited, resulting to the improvement of fuel consumption rate is reduced; At the initial stage of λ rising, the combustion delay period extending by crank angle (CA) 1° is corresponding to the combustion duration of 10% - 90% extending CA 1°. Increasing EGR rate and improving λ can effectively reduce the fuel consumption rate, and the EGR rate in equivalent combustion mode is 14%, which is equivalent to the contribution to fuel consumption rate in lean combustion mode when λ is 1.35. When λ reaches 1.27, the fuel consumption rate in lean burn mode can be reduced by 7.5% than that in equivalent combustion mode under the condition of 14% EGR rate.

Key words: gasoline engine, lean burned, Miller-cycle, exhaust gas recirculation (EGR), combustion visualization

CLC Number:

TK421.5

YIN Aiyong, HUANG Zhaoming, WANG Li, SHEN Kai, CHEN Weiguo. Analysis of lean combustion and emission characteristics of Miller cycle gasoline engine[J]. Journal of Automotive Safety and Energy, 2021, 12(3): 402-409.

Figures/Tables 12

References 20

[1]	Podevin P, Clenci A, Descombes G. Influence of the lubricating oil pressure and temperature on the performance at low speeds of a centrifugal compressor for an automotive engine[J]. *Appl Therm Engi*, 2011, 31(2-3):194-201.
[2]	Wong P K, Huang W, Chi M V, et al. Adaptive neural tracking control for automotive engine idle speed regulation using extreme learning machine[J]. *Neural Comput Appl*, 2020, 32(2):14399-14409. doi: 10.1007/s00521-019-04482-5 URL
[3]	董非, 苑天林, 王志明, 等. 无水丙二醇冷却液对柴油机性能影响的试验[J]. 内燃机学报, 2021, 39(1):81-87.
	DONG Fei, YUAN Tianlin, WANG Zhiming, et al. Experiment on the influence of anhydrous propylene glycol coolant on the performance of diesel engine[J]. *Chin Inter Comb Engi Engineering*, 2021, 39(1):81-87. (in Chinese)
[4]	PAN Xuewei, ZHAO Yinghua, LOU Diming, et al. Study of the Miller cycle on a turbocharged DI gasoline engine regarding fuel economy improvement at part load[J]. *Energies*, 2020, 13(6):1500-1526. doi: 10.3390/en13061500 URL
[5]	赵立峰, 苏向阳, 于秀敏. EGR和稀燃对GDI发动机性能和排放特性的影响[J]. 内燃机学报, 2020, 38(2):126-132.
	ZHAO Lifeng, SU Xiangyang, YU Xiumin. Investigation on performance and emissions of a GDR engine with egr and lean burn[J]. *Chin Inter Comb Engi Engineering*, 2020, 38(2):126-132. (in Chinese)
[6]	李小平, 洪伟, 解方喜, 等. 应用推迟点火、废气再循环及过稀混合气降低稀燃甲醇发动机NO_x排放[J]. 吉林大学学报(工学版), 2016, 46(5):1478-1483.
	LI Xiaoping, HONG Wei, XIE Fangxi, et al. Lean burn engine NO_x emission reduction of a lean-burn methanol engine by retarding ignition timing, exhaust gas recirculation and leaner air/fuel mixture[J]. *J Jilin Univ (Engi Tech Ed)*, 2016, 46(5):1478-1483. (in Chinese)
[7]	ZHAO Jinxing. Research and application of over-expansion cycle (Atkinson and Miller) engines - A review[J]. *Appl Energ, 2017, 185*:300-319. doi: 10.1016/j.apenergy.2016.10.063 URL
[8]	黄昭明, 沈凯, 安宗权, 等. 不同压缩比Miller循环和低压废气再循环对增压直喷汽油机性能影响[J]. 内燃机工程, 2019, 40(4):13-18.
	HUANG Zhaoming, SHEN Kai, AN Zongquan, et al. Effects of Miller cycle of different compression ratios and low pressure EGR on performance of turbocharged gasoline direct injection engine[J]. *Chin Inter Comb Engi Engineering*, 2019, 40(4):13-18. (in Chinese)
[9]	Imperato M, Kaario O, Sarjovaara T, et al. Split fuel injection and Miller cycle in a large-bore engine[J]. *Appl Energ, 2016, 162*(1):289-297. doi: 10.1016/j.apenergy.2015.10.041 URL
[10]	蔡文远, 徐焕祥, 马帅营, 等. 采用高能点火的均质稀薄燃烧汽油机试验[J]. 内燃机学报, 2020, 38(4):298-303.
	CAI Wenyuan, XU Huanxiang, MA Shuaiying, et al. Experiment on a homogeneous lean burn gasoline engine with high-energy ignition[J]. *Chin Inter Comb Engi Engineering*, 2020, 38(4):298-303. (in Chinese)
[11]	Amann M, Alger T, Mehta D. The effect of EGR on low-speed pre-ignition in boosted SI engines[J]. *SAE Int’l J Engi*, 2011, 4(1):235-245.
[12]	FENG Dengquan, WEI Haiqiao, PAN Mingzhang. Comparative study on combined effects of cooled EGR with intake boosting and variable compression ratios on combustion and emissions improvement in a SI engine[J]. *Appl Therm Engi, 2018, 131*:192-200.
[13]	Grandin B, Angstrom H E, Stalhammar P. Knock suppression in a turbocharged SI engine by using cooled EGR [C] // SAE World Congress and Exhibition. Detroit, USA, 1998:1998-98-2476.
[14]	杨靖, 罗贤芳, 何联格, 等. 稀薄燃烧发动机改型设计及正时策略优化[J]. 汽车工程, 2020, 42(4):439-444, 476.
	YANG Jing, LUO Xianfang, HE Liange, et al. Lean burn engine retrofit design and timing strategy op-timization[J]. *Autom Engi*, 2020, 42(4):439-444, 476. (in Chinese)
[15]	吴锡江, 王志宇, 尹琪. 高能点火在稀薄燃烧汽油机中的影响因素研究[J]. 车用发动机, 2020(5):1-10, 72.
	WU Xijiang, WANG Zhiyu, YIN Qi. Influencing factors of high-energy ignition in lean-burn gasoline engine[J]. *Vehic Engi*, 2020(5):1-10, 72. (in Chinese)
[16]	SU Jianye, XU Min, LI Tie, et al. Combined effects of cooled EGR and a higher geometric compression ratio on thermal efficiency improvement of a downsized boosted spark-ignition direct-injection engine[J]. *Energ Conv Manag*, 2014, 78(2):65-73. doi: 10.1016/j.enconman.2013.10.041 URL
[17]	赵立峰, 苏向阳, 于秀敏. EGR和稀燃对GDI发动机性能和排放特性的影响[J]. 内燃机学报, 2020, 38(2):126-132.
	ZHAO Lifeng, SU Xiangyang, YU Xiumin. Investigat-ion on performance and emissions of a GDI engine with EGR and lean burn[J]. *Chin Inter Combust Engine Engineering*, 2020, 38(2):126-132. (in Chinese)
[18]	杜辉, 江帆, 邓水根, 等. Miller循环及低压废气再循环技术对汽油机性能的影响研究[J]. 内燃机工程, 2020, 42(2):47-52+63.
	DU Hui, JIANG Fan, DENG Shuigen, et al. Research on the influence of Miller cycle and low pressure exhaust gas recirculation technology on the performance of gasoline engine [J]. *Chin Inter Comb Engi Engineering*, 2020, 42(2):47-52+63. (in Chinese)
[19]	Kim T Y, Park C, Oh S, et al. The effects of stratified lean combustion and exhaust gas recirculation on combustion and emission characteristics of an LPG direct injection engine[J]. *Energy, 2016, 115*:386-396. doi: 10.1016/j.energy.2016.09.025 URL
[20]	Lee S, Park S, Kim C, et al. Comparative study on EGR and lean burn strategies employed in an SI engine fueled by low calorific gas[J]. *Appl Energ, 2014, 129*:10-16. doi: 10.1016/j.apenergy.2014.04.082 URL

参数	四缸机	透明单缸机
型式	4缸、4冲程	单缸、4冲程
进气压力控制	涡轮增压系统	温控模拟增压系统
配气机构	D-VVT	相位可调式系统
喷油器布置	中置直喷	中置直喷
燃油供给系统	35 MPa供油系统	35 MPa供油系统

参数	四缸机	透明单缸机
型式	4缸、4冲程	单缸、4冲程
进气压力控制	涡轮增压系统	温控模拟增压系统
配气机构	D-VVT	相位可调式系统
喷油器布置	中置直喷	中置直喷
燃油供给系统	35 MPa供油系统	35 MPa供油系统