Expansion of HCCI Operating Region by the Combination of Direct Fuel Injection, Negative Valve Overlap and Internal Fuel Reformation

2003 ◽  
Author(s):  
Tomonori Urushihara ◽  
Koji Hiraya ◽  
Akihiko Kakuhou ◽  
Teruyuki Itoh
Keyword(s):  
Fuel Injection ◽  
Operating Region ◽  
Fuel Reformation ◽  
Negative Valve Overlap ◽  
Valve Overlap ◽  
Direct Fuel Injection

scholarly journals Numerical investigation into the effect of direct fuel injection on thermal stratification in HCCI engine

2017 ◽  
Vol 169 (2) ◽  
pp. 137-140
Author(s):  
Michał GĘCA ◽  
Jacek HUNICZ ◽  
Piotr JAWORSKI
Keyword(s):  
Combustion Chamber ◽  
Thermal Stratification ◽  
Fuel Injection ◽  
Injection Timing ◽  
Ignition Timing ◽  
Hcci Engine ◽  
Auto Ignition ◽  
Negative Valve Overlap ◽  
Valve Overlap ◽  
Direct Fuel Injection

Despite the fact that HCCI engines are distinguished by mixture homogeneity, some degree of stratification always appears inside a combustion chamber. It is especially applied to residual effect engines utilizing negative valve overlap. Mixture stratification is a result of the imperfect mixing of fresh air with trapped residuals. Direct fuel injection introduces stratification as well, due to fuel vaporization. As a consequence, the temperature within the combustion chamber is uneven. Thermal stratification affects auto-ignition timing and combustion evolution in a high extent. The purpose of this study was to evaluate a degree of thermal stratification in HCCI engine utilizing negative valve overlap. Investigations were performed using three-dimensional CFD model of the combustion system, made by using AVL FIRE software. Simulations were realized for various timings of fuel injection into the cylinder. It was found that fuel injection timing had a significant effect on the thermal stratification and resulting auto-ignition timing.

scholarly journals Investigation of transition between spark ignition and controlled auto-ignition combustion in a V6 direct-injection engine with cam profile switching

2008 ◽  
Vol 222 (10) ◽  
pp. 1911-1926 ◽  
Author(s):  
N Kalian ◽  
H Zhao ◽  
J Qiao
Keyword(s):  
Gasoline Engine ◽  
Fuel Injection ◽  
Direct Injection ◽  
Spark Ignition ◽  
High Lift ◽  
Auto Ignition ◽  
Operating Region ◽  
Low Load ◽  
Cam Profile ◽  
Direct Fuel Injection

Controlled auto-ignition (CAI) combustion, also known as homogeneous charge compression ignition (HCCI), can be achieved by trapping residuals with early exhaust valve closure in a direct-fuel-injection in-cylinder four-stroke gasoline engine (through the employment of low-lift cam profiles). Because the operating region is limited to low-load and midload operation for CAI combustion with a low-lift cam profile, it is important to be able to operate spark ignition (SI) combustion at high loads with a normal cam profile. A 3.0l prototype engine was modified to achieve CAI combustion, using a cam profile switching mechanism that has the capability to switch between high- and low-lift cam profiles. A strategy was used where a high-lift profile could be used for SI combustion and a low-lift profile was used for CAI combustion. Initial analysis showed that for a transition from SI to CAI combustion, misfire occurred in the first CAI transitional cycle. Subsequent experiments showed that the throttle opening position and switching time could be controlled to avoid misfire. Further work investigated transitions at different loads and from CAI to SI combustion.

Effect of Fuel Injection Timing During Negative Valve Overlap Period on a GDI-HCCI Engine

2018 ◽  
Author(s):  
Sok Ratnak ◽  
Jin Kusaka ◽  
Yasuhiro Daisho ◽  
Kei Yoshimura ◽  
Kenjiro Nakama
Keyword(s):  
Fuel Injection ◽  
Direct Injection ◽  
Single Pulse ◽  
Injection Timing ◽  
Pulse Injection ◽  
Hcci Combustion ◽  
Fuel Injection Timing ◽  
Intake Stroke ◽  
Negative Valve Overlap ◽  
Valve Overlap

Gasoline Direct Injection Homogeneous Charge Compression (GDI-HCCI) combustion is achieved by closing early the exhaust valves for trapping hot residual gases combined with direct fuel injection. The combustion is chemically controlled by multi-point auto-ignition which its main combustion phase can be controlled by direct injection timing of fuel. This work investigates the effect of single pulse injection timing on a supercharged GDI-HCCI combustion engine by using a four-stroke single cylinder engine with a side-mounted direct fuel injector. Injection of primary reference fuel PRF90 under the near-stoichiometric-boosted condition is studied. The fuel is injected during negative valve overlap (NVO) or recompression period for fuel reformation under low oxygen concentration and the injection is retarded to intake stroke for the homogeneous mixture. It is found that the early fuel injection in NVO period advances the combustion phasing compared with the retarded injection in the intake stroke. Noticeable slower combustion rate from intake stroke fuel injection is obtained compared with the NVO injection due to charge cooling effect. Zero-dimensional combustion simulations with multiple chemical reaction mechanisms are simulated to provide chemical understanding from the effect of fuel injection timing on intermediate species generations. The species such as C2H4, C3H6, CH4, and H2 are found to be formed during the NVO injection period from the calculations. The effects of single pulse injection timings on combustion characteristics such pressure rise rate, combustion stability, and emissions are also discussed in this study.

Study on knocking combustion in a diesel HCCI engine with fuel injection in negative valve overlap

Fuel ◽  
2013 ◽  
Vol 106 ◽  
pp. 478-483 ◽  
Author(s):  
Lei Shi ◽  
Kangyao Deng ◽  
Yi Cui ◽  
Shuan Qu ◽  
Wei Hu
Keyword(s):  
Fuel Injection ◽  
Hcci Engine ◽  
Negative Valve Overlap ◽  
Valve Overlap

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.

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