In theory, high compression ratio has the potential to improve the thermal efficiency and promote the power output of the SI engine. However, the application of high compression ratio is substantially limited by the knock in practical working process. The objective of this work is to comprehensively investigate the application of high compression ratio on a gasoline engine based on the Miller cycle with boost pressure and split injection. In this work, the specific optimum strategies for CR10 and CR12 were experimentally investigated respectively on a single cylinder DISI engine. It was found that a high level of Miller cycle with a higher boost pressure could be used in CR12 to achieve an effective compression ratio similar to CR10, which could eliminate the knock limits at a high compression ratio and high load. To verify the advantages of the high compression ratio, the fuel economy and power performance of CR10 and CR12 were compared at full and partial loads. The result revealed that, compared with CR10, a similar power performance and a reduced fuel consumption of CR12 at full load could be achieved by using the strong Miller cycle and split injection. At partial load, the conditions of CR12 had very superior fuel economy and power performance compared to those of CR10.
卫海桥, YU Jie, 周磊. 通过使用带有增压压力和分流喷射的米勒循环的爆震抑制，以高压缩比改善发动机性能[J]. Frontiers in Energy, 2019, 13(4): 691-706.
Haiqiao WEI, Jie YU, Lei ZHOU. Improvement of engine performance with high compression ratio based on knock suppression using Miller cycle with boost pressure and split injection. Front. Energy, 2019, 13(4): 691-706.
Combustion phasing as defined by the crank angle of 50% cumulative heat release (°CA)
CAD
Crank angle degree
COV
Coefficient of variation
CR
Compression ratio
DISI
Direct injection spark ignition
DVVT
Dual variable valve timing
EGR
Exhaust gas recirculation
EIVC
Early intake valve closure
GDI
Gasoline direct injection
IT
Ignition timing
LIVC
Late intake valve closure
MAPO
Maximum amplitude of filtered pressure oscillations
Pmax
Maximum pressure
RON
Research octane number
SI
Spark ignition
SOI
Start of injection
WOT
Widely open throttle
η
Effective thermal efficiency
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