转速拓展下喷油策略对柴油机低负荷预混燃烧的影响

doi:10.16183/j.cnki.jsjtu.2021.433

摘要/Abstract

摘要：

利用试验结合数值模拟的手段研究重型柴油机低负荷转速拓展下,多次喷油策略对预混充量压燃(PCCI)燃烧的影响,得出重型柴油机低负荷喷雾燃烧的普适优化方向:喷油定时应与燃烧室形状配合,使油、气、室三者结合,最大程度地利用燃烧室的形状优势;转速升高后采用多次喷油策略能够克服喷油持续期延长带来的喷油速率降低、油气混合程度降低等缺陷.优化喷油策略后,低转速单次喷油工况下NO_x排放量降低38%,碳烟排放量降低1个数量级,指示热效率提高8.66%;中转速单次喷油工况下,在指示热效率保持不变的情况下NO_x排放量降低59.3%,碳烟排放量降低70%;高转速单次喷油工况下,指示热效率和NO_x排放量略有升高,碳烟排放量显著降低.此外,研究发现,随着转速的提升,多次喷油策略对指示热效率与排放量的影响逐渐增强,多次喷油策略的优化效果相对低转速时更加明显.

关键词: 内燃机, 转速拓展, 喷油策略, 预混充量压燃燃烧, 排放, 指示热效率

Abstract:

In this paper, the influence of the multiple injection strategy on premixed charge compression ignition (PCCI) combustion of a heavy-duty diesel engine in low load speed extension is studied experimentally and numerically, and the general optimization direction of low-load spray combustion of a heavy-duty diesel engine is obtained. The injection timing should match the shape of the combustion chamber, so that the oil, gas, and chamber are combined to make full use of the advantage of the shape of the combustion chamber. As the speed increases, the multi-injection strategy can overcome the defects such as the decrease of injection rate and the decrease of oil-gas mixing degree caused by the extension of injection duration. For single injection at a low speed, through optimizing the injection strategy, the NO_x emission is reduced by 38%, the soot emission is decreased by one order of magnitude, and the indicated thermal efficiency is increased by 8.66%. For single injection at a medium speed, the indicated thermal efficiency remains unchanged, the NO_x emission is reduced by 59.3%, and the soot emission is reduced by 70%. For single injection at a high speed, the thermal efficiency and the NO_x emission are increased slightly while the soot emission is decreased significantly. In addition, it is found that with the increase of speed, the influence of the multiple injection strategy on indicated thermal efficiency and emissions is gradually increased, and the optimization effect of the multiple injection strategy is more obvious than that of low speed.

Key words: internal combustion engine, speed extension, fuel injection strategy, premixed charge compression ignition (PCCI) combustion, emissions, indicated thermal efficiency

中图分类号:

TK422

范超, 鹿盈盈, 刘一泽. 转速拓展下喷油策略对柴油机低负荷预混燃烧的影响[J]. 上海交通大学学报, 2023, 57(8): 1055-1066.

FAN Chao, LU Yingying, LIU Yize. Effect of Injection Strategy on Low Load Premixed Combustion of a Diesel Engine in Engine Speed Extension[J]. Journal of Shanghai Jiao Tong University, 2023, 57(8): 1055-1066.

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参数	数值
缸径/mm	116
行程/mm	150
连杆长度/mm	224.5
涡流比	1.1
发动机转速/(r·min^-1)	1 000/1 400/1 800
喷油系统	高压共轨
喷油压力/MPa	160
喷孔数量	8
喷孔直径/mm	0.169
喷孔之间夹角/(°)	149
最大爆发压力/MPa	23
排量/L	9.5
压缩比	18.5
燃油种类	国V0号柴油

S/ (r·min^-1)	工况	R/%	φ_CA/(°) (P2SOI/D2/P1SOI/ D1/MSOI/D)	E/%
1 000	1	0	0/0/0/0/-30/4.1	43.19
	2	0	0/0/0/0/-25/4.1	45.24
	3	0	0/0/0/0/-15/4.1	51.99
	4	20	0/0/-30/0.6/-20/2.1	46.35
	5	30	0/0/-30/0.9/-20/1.8	45.19
	6	40	0/0/-30/1.1/-20/1.6	45.25
	7	50	0/0/-30/1.3/-20/1.3	45.96
	8	60	0/0/-30/1.6/-20/1.1	42.08
	9	70	0/0/-30/1.8/-20/0.9	52.00
1 400	1	0	0/0/0/0/-30/5.8	42.96
	2	0	0/0/0/0/-25/5.8	42.72
	3	0	0/0/0/0/-15/5.8	48.08
	4	20	0/0/-30/1/-20/3.6	44.47
	5	30	0/0/-30/1.5/-20/3.1	45.14
	6	40	0/0/-30/1.9/-20/2.7	44.83
	7	50	0/0/-30/2.3/-20/2.3	44.50
	8	60	0/0/-30/2.7/-20/1.9	44.68
	9	70	0/0/-30/3.1/-20/1.5	50.50

方案	R/%	φ_CA/(°) (P2SOI/D2/P1SOI/D1/MSOI/D)	N/[g·(kW·h)^-1]	C/[g·(kW·h)^-1]	E/%
基准工况	0	0/0/0/0/-15/4.1	5.92×10^-2	1.02×10^-4	51.99
对比工况1	60	0/0/-30/1.6/-20/1.1	6.65×10^-2	4.21×10^-4	32.92
对比工况2	40	0/0/-30/1.1/-20/1.6	7.87×10^-2	7.77×10^-4	39.02
优化方案1	0	0/0/0/0/-11/4.1	1.89×10^-2	2.21×10^-4	54.40
优化方案2	60	0/0/-21/1.6/-11/1.1	1.10×10^-1	4.99×10^-5	46.58
优化方案3	40	0/0/-20/1.1/-10/1.6	3.64×10^-2	1.13×10^-5	60.65
优化方案4	20+20	-20/0.6/-13/0.6/10/1.6	2.76×10^-2	2.73×10^-5	60.00

方案	R/%	φ_CA/(°) (P2SOI/D2/P1SOI/D1/MSOI/D)	N/[(g·(kW·h)^-1]	C/[g·(kW·h)^-1]	E/%
基准工况	0	0/0/0/0/-15/5.8	3.91×10^-2	2.09×10^-3	48.08
对比工况1	50	0/0/-30/2.3/-20/2.3	3.02×10^-2	2.21×10^-3	46.64
对比工况2	40	0/0/-30/1.9/-20/2.7	4.09×10^-2	2.20×10^-3	41.34
优化方案1	40	0/0/-25/1.9/-15/2.7	4.42×10^-2	8.24×10^-4	45.58
优化方案2	40	0/0/-20/1.9/-10/2.7	2.34×10^-2	8.69×10^-4	47.62
优化方案3	50	0/0/-20/2.3/-10/2.3	2.04×10^-2	3.44×10^-4	47.77
优化方案4	25+25	-20/0.6/-12/0.6/-10/2.7	1.59×10^-2	6.18×10^-4	48.41

方案	R/%	φ_CA/(°) (P2SOI/D2/P1SOI/D1/MSOI/D)	N/[g·(kW·h)^-1]	C/[g·(kW·h)^-1]	E/%
1	0	0/0/0/0/-30/7.4	2.18×10^-2	2.06×10^-3	42.14
2	0	0/0/0/0/-25/7.4	2.02×10^-2	3.68×10^-3	42.62
3	0	0/0/0/0/-15/7.4	1.06×10^-2	1.01×10^-2	47.98
4	40	0/0/-30/3/-20/4.6	1.97×10^-2	6.7×10^-3	48.84
5	50	0/0/-30/3.7/-20/3.9	1.99×10^-2	7.09×10^-3	48.61
6	40	0/0/-25/3/-15/4.6	1.64×10^-2	3.37×10^-3	49.55
7	50	0/0/-25/3.7/-15/3.9	1.88×10^-2	3.08×10^-3	49.83
8	20+20	-25/1.9/-18/1.9/-15/3.9	1.32×10^-2	3.27×10^-3	48.88
9	25+25	-25/1.9/-18/1.9/-15/3.9	1.34×10^-2	5.67×10^-3	48.70