Ignition timing control of homogeneous charge compression ignition engines by pulsed flame jets

2002 ◽  
Vol 174 (5-6) ◽  
pp. 129-140 ◽  
Author(s):  
E. Murase ◽  
K. Hanada
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Timing Control ◽  
Compression Ignition Engines ◽  
Homogeneous Charge

Study of High Load Operation Limit Expansion for Gasoline Compression Ignition Engines

2006 ◽  
Vol 128 (2) ◽  
pp. 377-387 ◽  
Author(s):  
Koudai Yoshizawa ◽  
Atsushi Teraji ◽  
Hiroshi Miyakubo ◽  
Koichi Yamaguchi ◽  
Tomonori Urushihara
Keyword(s):  
Fuel Injection ◽  
Control Method ◽  
Combustion Process ◽  
High Load ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Timing Control ◽  
Load Range ◽  
Compression Ignition Engines ◽  
Spark Plug

In this research, combustion characteristics of gasoline compression ignition engines have been analyzed numerically and experimentally with the aim of expanding the high load operation limit. The mechanism limiting high load operation under homogeneous charge compression ignition (HCCI) combustion was clarified. It was confirmed that retarding the combustion timing from top dead center (TDC) is an effective way to prevent knocking. However, with retarded combustion, combustion timing is substantially influenced by cycle-to-cycle variation of in-cylinder conditions. Therefore, an ignition timing control method is required to achieve stable retarded combustion. Using numerical analysis, it was found that ignition timing control could be achieved by creating a fuel-rich zone at the center of the cylinder. The fuel-rich zone works as an ignition source to ignite the surrounding fuel-lean zone. In this way, combustion consists of two separate auto-ignitions and is thus called two-step combustion. In the simulation, the high load operation limit was expanded using two-step combustion. An engine system identical to a direct-injection gasoline (DIG) engine was then used to validate two-step combustion experimentally. An air-fuel distribution was created by splitting fuel injection into first and second injections. The spark plug was used to ignite the first combustion. This combustion process might better be called spark-ignited compression ignition combustion (SI-CI combustion). Using the spark plug, stable two-step combustion was achieved, thereby validating a means of expanding the operation limit of gasoline compression ignition engines toward a higher load range.

Characterizing the cyclic variability of ignition timing in a homogeneous charge compression ignition engine fuelled with n-heptane/iso-octane blend fuels

2008 ◽  
Vol 9 (5) ◽  
pp. 361-397 ◽  
Author(s):  
M Shahbakhti ◽  
C R Koch
Keyword(s):  
Equivalence Ratio ◽  
Homogeneous Charge Compression Ignition ◽  
Coolant Temperature ◽  
Cyclic Variation ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Compression Ignition Engine ◽  
Hcci Combustion ◽  
Cyclic Variations ◽  
Homogeneous Charge

The cyclic variations of homogeneous charge compression ignition (HCCI) ignition timing is studied for a range of charge properties by varying the equivalence ratio, intake temperature, intake pressure, exhaust gas recirculation (EGR) rate, engine speed, and coolant temperature. Characterization of cyclic variations of ignition timing in HCCI at over 430 operating points on two single-cylinder engines for five different blends of primary reference fuel (PRF), (iso-octane and n-heptane) is performed. Three distinct patterns of cyclic variation for the start of combustion (SOC), combustion peak pressure ( Pmax), and indicated mean effective pressure (i.m.e.p.) are observed. These patterns are normal cyclic variations, periodic cyclic variations, and cyclic variations with weak/misfired ignitions. Results also show that the position of SOC plays an important role in cyclic variations of HCCI combustion with less variation observed when SOC occurs immediately after top dead centre (TDC). Higher levels of cyclic variations are observed in the main (second) stage of HCCI combustion compared with that of the first stage for the PRF fuels studied. The sensitivity of SOC to different charge properties varies. Cyclic variation of SOC increases with an increase in the EGR rate, but it decreases with an increase in equivalence ratio, intake temperature, and coolant temperature.

Modeling the Effects of Steam-Fuel Reforming Products on Homogeneous Charge Compression Ignition of n-Heptane

2009 ◽  
Author(s):  
Francisco Posada ◽  
Nigel N. Clark ◽  
Aleksandr Kozlov ◽  
Martin Linck ◽  
Dmitri Boulanov ◽  
...  
Keyword(s):  
Species Composition ◽  
Heat Release ◽  
Homogeneous Charge Compression Ignition ◽  
Zone Model ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Fuel Reforming ◽  
Total N ◽  
Temperature Heat ◽  
Homogeneous Charge

Homogeneous Charge Compression Ignition (HCCI) offers benefits of high efficiency with low emissions, but suffers load range limitations and control issues. A method to improve control of HCCI was numerically investigated based on two separate fuel streams with different autoignition characteristics to regulate timing and heat release at specific operational conditions. In this numerical study n-heptane was selected as the primary fuel, and the secondary fuel was defined as a reformed product of n-heptane (RG). The reformed fuel species composition was experimentally determined based on steam/n-heptane reforming process at a steam/carbon mole ratio of 2:1. In addition to H2 and CO, the reformed fuel stream was composed of CH4, CO2, H2O and non-reformed n-heptane. A single zone model using a detailed chemical kinetic mechanism was implemented on CHEMKIN to study the effects of base fuel and steam-fuel reforming products on the ignition timing and heat release characteristics. The study was performed considering the reformed fuel species composition at total n-heptane conversion (stoichiometric) and also at the composition corresponding to a specific set of operational reforming temperatures. The computational model confirmed that the reformed products have a strong influence on the low temperature heat release (LTHR) region, affecting the onset of the high temperature heat release (HTHR). The ignition timing was proportionally delayed with respect to the baseline fuel case when higher concentrations of reformed gas were used.

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