Experimental and numerical investigation of effects of compression ratio on dual-fuel combustion at medium and high load

doi:10.3969/j.issn.1674-8484.2020.04.012

Abstract

Abstract:

The rough combustion at the medium and high load has always been a challenge for the dual-fuel combustion. The effects of compression ratio (CR) on the dual-fuel combustion at medium and high load were investigated experimentally and numerically. The experimental results showed that the highest gasoline ratio in homogeneous charge induced ignition (HCII) combustion increased from about 33% to about 54% by reducing the compression ratio from 17.4 to 14.4. As a result, the NO_x, soot and CO emissions were further reduced but the total hydrocarbons (THC) emissions got increased. The simulation results showed that the temperature of gasoline could be lowered by about 750 K; The NO_x and soot emissions were mainly distributed in the diesel combustion area, and they could be reduced with the increasing gasoline ratio; The THC emissions in the cylinder crevice and the CO emissions generated from the incomplete combustion of gasoline can be eliminated by the gasoline auto-ignition. In conclusion, the rough combustion at the medium and high load can be alleviated and the performance of the dual-fuel combustion can be improved by reducing the compression ratio.

Key words: multi-cylinder engine dual-fuel combustion, compression ratio, homogeneous charge induced ignition (HCII), gasoline ratio, simulation

CLC Number:

TK421.2

REN Shuojin, ZHANG Ming, GUO Yong, YAN Yan, WANG Zhi, WANG Jianxin. Experimental and numerical investigation of effects of compression ratio on dual-fuel combustion at medium and high load[J]. Journal of Automotive Safety and Energy, 2020, 11(4): 518-528.

Figures/Tables 23

References 16

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汽缸数	6
缸径	108 mm
冲程	136 mm
连杆长度	209.7 mm
排量	7.47 L
压缩比(原机)	17.4
额定功率	220 kW
额定转速	2 300 r/min
最大转矩	1.250 kNm
最大转矩工况转速	1 700 r/min

汽缸数	6
缸径	108 mm
冲程	136 mm
连杆长度	209.7 mm
排量	7.47 L
压缩比(原机)	17.4
额定功率	220 kW
额定转速	2 300 r/min
最大转矩	1.250 kNm
最大转矩工况转速	1 700 r/min

参数	汽油	柴油
十六烷值CN	-	56.5
辛烷值RON	95.1	-
密度(20 ℃) /（kg·L^-1）	0.753	0.830
热值 /（MJ·kg^-1）	42.84	42.68
运动粘度 (20 ℃) /（mm²·s^-1）	0.75	4.13
硫质量分数含量 / 10^-6	21.0	4.3

参数	汽油	柴油
十六烷值CN	-	56.5
辛烷值RON	95.1	-
密度(20 ℃) /（kg·L^-1）	0.753	0.830
热值 /（MJ·kg^-1）	42.84	42.68
运动粘度 (20 ℃) /（mm²·s^-1）	0.75	4.13
硫质量分数含量 / 10^-6	21.0	4.3

	区域	级别	时段
自适应	整个计算域	3	永久
嵌入式	气缸盖表面	1	永久
	气缸壁表面	1	永久
	活塞表面	1	永久
	喷束圆锥	2	每次喷油开始到结束后去曲柄转角CA = 5°