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

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.

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

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.

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

The Low Load Limit of Gasoline Partially Premixed Combustion Using Negative Valve Overlap

2012 ◽  
Author(s):  
Patrick Borgqvist ◽  
Öivind Andersson ◽  
Per Tunestål ◽  
Bengt Johansson
Keyword(s):  
Engine Speed ◽  
Premixed Combustion ◽  
Partially Premixed Combustion ◽  
Operating Region ◽  
Load Limit ◽  
Low Load ◽  
Negative Valve Overlap ◽  
Valve Overlap ◽  
Injection Strategies ◽  
High Octane

Partially premixed combustion has the potential of high efficiency and simultaneous low soot and NOx emissions. Running the engine in PPC mode with high octane number fuels has the advantage of a longer premix period of fuel and air which reduces soot emissions, even at higher loads. The problem is the ignitability at low load and idle operating conditions. The objective is to investigate different multiple-injection strategies in order to further expand the low load limit and reduce the dependency on negative valve overlap in order to increase efficiency. The question is, what is the minimum attainable load for a given setting of negative valve overlap and fuel injection strategy. The experimental engine is a light duty diesel engine equipped with a fully flexible valve train system. The engine is run without boost at engine speed 800 rpm. The fuel is 87 RON gasoline. A turbocharger is typically used to increase the boost pressure, but at low engine speed and load the available boost is expected to be limited. The in-cylinder pressure and temperature around top-dead-center will then be too low to ignite high octane number fuels. A negative valve overlap can be used to extend the low engine speed and load operating region. But one of the problems with negative valve overlap is the decrease in gas-exchange efficiency due to heat-losses from recompression of the residual gases. Also, the potential temperature increase from the trapped hot residual gases is limited at low load due to the low exhaust gas temperature. In order to expand the low load operating region further, more advanced injection strategies are investigated.

Model-Based Estimation of Turbocharger Requirements for Boosting an HCCI Engine

2010 ◽  
Author(s):  
Sotirios Mamalis ◽  
Aristotelis Babajimopoulos
Keyword(s):  
High Pressures ◽  
Simulation Software ◽  
Exhaust Gas ◽  
University Of Michigan ◽  
Hcci Engine ◽  
Engine Simulation ◽  
Hcci Combustion ◽  
Load Limit ◽  
Intake Pressure ◽  
The University

Turbocharged Homogeneous Charge Compression Ignition (HCCI) has been modeled and has demonstrated the potential to extend the engine’s upper load limit. A commercially available engine simulation software (GT-Power®) coupled to the University of Michigan HCCI combustion and heat transfer correlations was used to model a single cylinder boosted HCCI engine including a phenomenological turbocharger model. The scope of this study is to explore the upper load limits of boosted HCCI operation and to identify turbocharger requirements for boosting the HCCI. The results of this study are consistent with the literature: Boosting helps increase the HCCI upper load limit, but matching of turbochargers is a problem. In addition, the low exhaust gas enthalpy resulting from HCCI combustion leads to high pressures in the exhaust manifold and increased pumping work. It is shown that loads as high as 17 bar NMEP can be reached at low engine speeds, when the intake pressure is 3 bar.

scholarly journals On the High Load Limit of Boosted Gasoline HCCI Engine Operating in NVO Mode

2010 ◽  
Vol 3 (1) ◽  
pp. 35-45 ◽  
Author(s):  
Robert Scaringe ◽  
Craig Wildman ◽  
Wai K. Cheng
Keyword(s):  
High Load ◽  
Hcci Engine ◽  
Load Limit

scholarly journals INCREASE OF HIGH LOAD LIMIT IN A GASOLINE HCCI ENGINE

2015 ◽  
Vol 19 (4) ◽  
pp. 231-238
Author(s):  
Jacek Hunicz ◽  
Paweł Kordos ◽  
Michał Gęca
Keyword(s):  
High Load ◽  
Hcci Engine ◽  
Load Limit
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