Expanding the Low Load Limit of HCCI Combustion Process Using EIVO Strategy in a 4VVAS Gasoline Engine

2012 ◽  
Author(s):  
Tao Chen ◽  
Hui Xie ◽  
Le Li ◽  
Weifei Yu ◽  
Lianfang Zhang ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Combustion Process ◽  
Hcci Combustion ◽  
Load Limit ◽  
Low Load

HCCI Operability Limits: The Impact of Refinery Stream Gasoline Property Variation

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Joshua S. Lacey ◽  
Zoran S. Filipi ◽  
Sakthish R. Sathasivam ◽  
William J. Cannella ◽  
Peter A. Fuentes-Afflick
Keyword(s):  
Thermal Conditions ◽  
The United States ◽  
High Load ◽  
Fuel Properties ◽  
Research Octane Number ◽  
Property Variation ◽  
Hcci Combustion ◽  
Load Limit ◽  
Low Load ◽  
The Impact

Homogeneous charge compression ignition (HCCI) combustion is highly dependent on in-cylinder thermal conditions favorable to autoignition, for a given fuel. Fuels available at the pump can differ considerably in composition and autoignition chemistry; hence strategies intended to bring HCCI to market must account for the fuel variability. To this end, a test matrix consisting of eight gasoline fuels composed of blends made solely from refinery streams was investigated in an experimental, single cylinder HCCI engine. The base compositions were largely representative of gasoline one would expect to find across the United States, although some of the fuels had slightly lower average octane values than the ASTM minimum specification of 87. All fuels had 10% ethanol by volume included in the blend. The properties of the fuels were varied according to research octane number (RON), sensitivity (S=RON-MON) and the volumetric fractions of aromatics and olefins. For each fuel, a sweep of the fuelling was carried out at each speed from the level of instability to excessive ringing to determine the limits of HCCI operation. This was repeated for a range of speeds to determine the overall operability zone. The fuels were kept at a constant intake air temperature during these tests. The variation of fuel properties brought about changes in the overall operating range of each fuel, as some fuels had more favorable low load limits, whereas others enabled more benefit at the high load limit. The extent to which the combustion event changed from the low load limit to the high load limit was examined as well, to provide a relative criterion indicating the sensitivity of HCCI range to particular fuel properties.

HCCI Operability Limits: The Impact of Refinery Stream Gasoline Property Variation

2012 ◽  
Author(s):  
Joshua S. Lacey ◽  
Sakthish R. Sathasivam ◽  
Zoran S. Filipi ◽  
William J. Cannella ◽  
Peter A. Fuentes-Afflick
Keyword(s):  
Thermal Conditions ◽  
The United States ◽  
High Load ◽  
Fuel Properties ◽  
Property Variation ◽  
Hcci Combustion ◽  
Auto Ignition ◽  
Load Limit ◽  
Low Load ◽  
The Impact

HCCI combustion is highly dependent on in-cylinder thermal conditions favorable to auto-ignition, for a given fuel. Fuels available at the pump can differ considerably in composition and auto-ignition chemistry, hence strategies intended to bring HCCI to market must account for the fuel variability. To this end, a test matrix consisting of eight gasoline fuels composed of blends made solely from refinery streams was investigated in an experimental, single cylinder HCCI engine. The base compositions were largely representative of gasoline one would expect to find across the United States, although some of the fuels had slightly lower average octane values than the ASTM minimum specification of 87. All fuels had 10% ethanol by volume included in the blend. The properties of the fuels were varied according to research octane number (RON), sensitivity (S=RON−MON) and the volumetric fractions of aromatics and olefins. For each fuel, a sweep of the fuelling was carried out at each speed from the level of instability to excessive ringing to determine the limits of HCCI operation. This was repeated for a range of speeds to determine the overall operability zone. The fuels were kept at a constant intake air temperature during these tests. The variation of fuel properties brought about changes in the overall operating range of each fuel, as some fuels had more favorable low load limits, whereas others enabled more benefit at the high load limit. The extent to which the combustion event changed from the low load limit to the high load limit was examined as well, to provide a relative criterion indicating the sensitivity of HCCI range to particular fuel properties.

scholarly journals Static Friction between Elastic Solids due to Random Asperities

2000 ◽  
Vol 651 ◽  
Author(s):  
J. B. Sokoloff
Keyword(s):  
Unit Area ◽  
Static Friction ◽  
Elastic Solids ◽  
Weakly Interacting ◽  
Load Limit ◽  
Low Load ◽  
Atomically Flat

AbstractSeveral workers have argued that should be negligible static friction per unit area in the macroscopic solid limit for interfaces between both incommensurate and disordered atomically flat weakly interacting solids. In contrast, the present work argues that in the low load limit, when one considers disorder on the multiasperity scale, the asperties act independently to a good approximation. This can account for the virtual universal occurence of static friction.

Primary Reference Fuel Behavior in a HCCI Engine near the Low-Load Limit

2008 ◽  
Vol 1 (1) ◽  
pp. 1098-1109 ◽  
Author(s):  
Teppei Ogura ◽  
John P. Angelos ◽  
William H. Green ◽  
Wai K. Cheng ◽  
Thomas E. Kenney ◽  
...  
Keyword(s):  
Hcci Engine ◽  
Load Limit ◽  
Low Load ◽  
Primary Reference ◽  
Fuel Behavior

HCCI Load Expansion Opportunities Using a Fully Variable HVA Research Engine to Guide Development of a Production Intent Cam-Based VVA Engine: The Low Load Limit

2012 ◽  
Vol 5 (3) ◽  
pp. 1149-1162 ◽  
Author(s):  
Adam Weall ◽  
James P. Szybist ◽  
K. Dean Edwards ◽  
Matthew Foster ◽  
Keith Confer ◽  
...  
Keyword(s):  
Load Limit ◽  
Low Load

Effects of passive pre-chamber jet ignition on combustion and emission at gasoline engine

2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110671
Author(s):  
Wei Duan ◽  
Zhaoming Huang ◽  
Hong Chen ◽  
Ping Tang ◽  
Li Wang ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Gasoline Engine ◽  
Combustion Process ◽  
Pressure Rise ◽  
Spark Ignition ◽  
Combustion Stability ◽  
Intake Valve ◽  
Part Load ◽  
Significant Difference ◽  
Valve Opening

Pre-chamber jet ignition is a promising way to improve fuel consumption of gasoline engine. A small volume passive pre-chamber was tested at a 1.5L turbocharged GDI engine. Combustion and emission characteristics of passive pre-chamber at low-speed WOT and part load were studied. Besides, the combustion stability of the passive pre-chamber at idle operation has also been studied. The results show that at 1500 r/min WOT, compared with the traditional spark ignition, the combustion phase of pre-chamber is advanced by 7.1°CA, the effective fuel consumption is reduced by 24 g/kW h, and the maximum pressure rise rate is increased by 0.09 MPa/°CA. The knock tendency can be relieved by pre-chamber ignition. At part load of 2000 r/min, pre-chamber ignition can enhance the combustion process and improve the combustion stability. The fuel consumption of pre-chamber ignition increases slightly at low load, but decreases significantly at high load. Compared with the traditional spark ignition, the NOx emissions of pre-chamber increase significantly, with a maximum increase of about 15%; the HC emissions decrease, and the highest decrease is about 36%. But there is no significant difference in CO emissions between pre-chamber ignition and spark plug ignition. The intake valve opening timing has a significant influence on the pre-chamber combustion stability at idle operation. With the delay of the pre-chamber intake valve opening timing, the CoV is reduced and can be kept within the CoV limit.

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