Experimental Study on the Characteristics of Knock under DI-HCCI Combustion Mode with Ethanol/Gasoline Mixed Fuel Tongji Univ

Format:

Conference/Event

Author/Creator:

Liu, Liu, author.

Contributor:

Chen, Yulin

Deng, Jun

Hu, Minzhang

Li, Liguang

Shi, Xian

Conference Name:

SAE 2013 World Congress & Exhibition (2013-04-16 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2013

Summary:

Gasoline homogeneous charge compression ignition (HCCI) canachieve high efficiency and extremely low NOX emissions. However,the working condition range of HCCI is limited by knock occurringduring engine operation. To achieve an expanded HCCI workingcondition range, it is necessary to explore a method predictingknock cases accurately to avoid knock occurring.Based on a DI-HCCI engine with ethanol/gasoline mixed fuel, theknock cases under different conditions have been investigated.In-cylinder pressure signals are used to identify the knock casesand the knock oscillations are extracted with fast Fouriertransform (FFT). The effects of the ethanol proportion in the fueland air/fuel ratio on the characteristics of knock have beenstudied.The results have shown that the knock parameters, such asmaximum frequency, start point angle and the duration, have closerelationship with the knock intensity. Stronger knock causes highermaximum frequency, earlier start point and longer duration, butwill lead to faster attenuations of knock oscillation. Furthermore,air/fuel ratios and the ethanol fraction have effects on the knockintensity. As air/fuel ratio decreases, the knock intensity,frequency and knock probability will be strengthened. When thefraction of ethanol increases, the knock amplitude, frequency andtendency will be impaired due to the high octane number of ethanol,which can also make the knock boundary expand effectively. From theanalysis results of combustion phasing CA10 and CA50, it shows thatethanol has significant effect on retarding combustion, which leadsto impaired knock. This retarding effect of ethanol is moresensitive with lower intake temperature. In addition, a 0-dimensioncombustion predicting model was set up in this paper. With therelationships found among knock and combustion parameters, such asair/fuel ratio, ethanol fraction and intake air temperature, thecombustion pressure and knock characteristics could be predictedwith an error below 10%

Notes:

Vendor supplied data

Publisher Number:

2013-01-0544

Access Restriction:

Restricted for use by site license