The combustion and emission characteristics of low temperature combustion at low load were investigated by changing strategies of internal and external EGR and injection pressure on a single cylinder diesel engine equipped with a electrohydraulic variable valve actuator system. The internal EGR was achieved by opening exhaust valve twice during the intake process. The test was conducted at engine speed of 1 500 r/min with 20 mg/cyc fuel injection. The results show that the ultralow NOx emission can be obtained by controlling EGR rates. The soot emission of internal EGR reduces at a high injection pressure，while HC and CO emissions of external EGR reduce at a low injection pressure. For the coupling control strategy of internal and external EGR, the increase of internal EGR ratio can reduce HC and CO emissions at a small range and a higher injection pressure is hence introduced to suppress soot emission. In addition, the increase of the external EGR ratio can achieve higher thermal efficiency.
ZHANG Xiangyu
,
ZHENG Zunqing
,
LI Yanfang
,
ZHU Yuxuan
,
GAO Yingying
,
YAO Mingfa
. Effects of Internal and External EGR and Injection Pressure on Low Temperature Combustion of Diesel Engine[J]. Vehicle Engine, 2017
, 0(5)
: 1
-5
.
DOI: 10.3969/j.issn.10012222.2017.05.001
