Experimental and Numerical Analysis on the Influence of Direct Fuel Injection Into O2-Depleted Environment of a GDI-HCCI Engine

2020 ◽  
Author(s):  
Ratnak Sok ◽  
Jin Kusaka
Keyword(s):  
Fuel Injection ◽  
Direct Injection ◽  
Injection Pressure ◽  
Single Pulse ◽  
Gasoline Direct Injection ◽  
Injection Timing ◽  
Rich Mixture ◽  
Intake Stroke ◽  
Shift Reaction ◽  
Direct Fuel Injection

Abstract Injected gasoline into the O2-depleted environment in the recompression stroke can be converted into light hydrocarbons due to thermal cracking, partial oxidation, and water-gas shift reaction. These reformate species influence the combustion phenomena of gasoline direct injection homogeneous charge compression ignition (GDI-HCCI) engines. In this work, a production-based single-cylinder research engine was boosted to reach IMEPn = 0.55 MPa in which its indicated efficiency peaks at 40–41%. Experimentally, the main combustion phases are advanced under single-pulse direct fuel injection into the negative valve overlap (NVO) compared with that of the intake stroke. NVO peak in-cylinder pressures are lower than that of motoring, which emphasizes that endothermic reaction occurs during the interval. Low O2 concentration could play a role in this evaporative charge cooling effect. This phenomenon limits the oxidation reaction, and the thermal effect is not pronounced. For understanding the recompression reaction phenomena, 0D simulation with three different chemical reaction mechanisms is studied to clarify that influences of direct injection timing in NVO on combustion advancements are kinetically limited by reforming. The 0D results show the same increasing tendencies of classical reformed species of rich-mixture such as C3H6, C2H4, CH4, CO, and H2 as functions of injection timings. By combining these reformed species into the main fuel-air mixture, predicted ignition delays are shortened. The effects of the reformed species on the main combustion are confirmed by 3D-CFD calculation, and the results show that OH radical generation is advanced under NVO fuel injection compared with that of intake stroke conditions thus earlier heat release and cylinder pressure are noticeable. Also, parametric studies on injection pressure and double-pulse injections on engine combustion are performed experimentally.

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.

Correlation of Ignitability with Injection Timing for Direct Injection Combustion Fuelled with Compressed Natural Gas and Gasoline

2003 ◽  
Vol 217 (6) ◽  
pp. 499-506 ◽  
Author(s):  
Z Huang ◽  
S Shiga ◽  
T Ueda ◽  
H Nakamura ◽  
T Ishima ◽  
...  
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Direct Injection ◽  
Injection Pressure ◽  
Gasoline Direct Injection ◽  
Injection Timing ◽  
Electrode Gap ◽  
Lean Burn ◽  
Compressed Natural Gas ◽  
Study Results

A study on the correlation of ignitability with fuel injection timing for direct injection combustion fuelled with natural gas and gasoline was carried out by using a rapid compression machine. The injection pressure of natural gas is 9 MPa and the injection pressure of gasoline is 7 MPa. The study results show that natural gas direct injection possesses higher momentum than that of gasoline, and this is beneficial to the combustion enhancement since a higher intensity of turbulence could be induced. Correlation of ignitability with injection timing shows better behaviour in natural gas direct injection, and this correlation is insensitive to injection modes in the case of natural gas. Thus, natural gas direct injection would have better engine applicability under cold-start conditions. The lean burn limits of natural gas and gasoline direct injection can extend to extremely low equivalence ratio when the ignitable stratified mixture exists around the spark electrode gap by optimizing the injection timing.

Experimental and Numerical Analysis on the Influences of Direct Fuel Injection into Oxygen-Depleted Environment of a Homogeneous Charge Compression Ignition Engine

2021 ◽  
pp. 1-29
Author(s):  
Ratnak Sok ◽  
Kei Yoshimura ◽  
Kenjiro Nakama ◽  
Jin Kusaka
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Fuel Injection ◽  
Double Pulse ◽  
Gasoline Direct Injection ◽  
Oh Radicals ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Intake Stroke ◽  
Direct Fuel Injection ◽  
Homogeneous Charge

Abstract The oxygen-depleted environment in the recompression stroke can convert gasoline fuel into light hydrocarbons due to thermal cracking, partial oxidation, and water-gas shift reactions. These reformate species can influence the combustion characteristics of gasoline direct injection homogeneous charge compression ignition (GDI-HCCI) engines. In this work, the combustion phenomena are investigated using a single-cylinder research engine under a medium load. The main combustion phases are experimentally advanced by direct fuel injection into the negative valve overlap (NVO) compared with that of intake stroke under single/double pulse injections. NVO peak in-cylinder pressures are lower than that of motoring due to the limited O2 concentration, emphasizing that endothermic reactions occur during the overlap. This phenomenon limits the oxidation reactions, and the thermal effect is not pronounced. The 0-D chemical kinetics results present the same increasing tendencies of classical reformed species of rich-mixture such as C3H6, C2H4, CH4, CO, and H2 as functions of injection timings. Predicted ignition delays are shortened due to the additions of these reformed species. The influences of the reformates on the main combustion are confirmed by 3-D CFD calculations, and the results show that OH radicals are advanced under NVO injections relative to intake stroke injections. Consequently, earlier heat release and cylinder pressure are noticeable. Parametric studies on the effects of injection pressure, double-pulse injection, and equivalence ratio on the combustion and emissions are also discussed experimentally.

Effect of Fuel Injection Pressure and Engine Speed on Performance, Emissions, Combustion, and Particulate Investigations of Gasohols Fuelled Gasoline Direct Injection Engine

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Nikhil Sharma ◽  
Avinash Kumar Agarwal
Keyword(s):  
Internal Combustion Engines ◽  
Fuel Injection ◽  
Driving Forces ◽  
Direct Injection ◽  
Engine Performance ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Primary Alcohols ◽  
Renewable Fuel

Abstract Fuel availability, global warming, and energy security are the three main driving forces, which determine suitability and long-term implementation potential of a renewable fuel for internal combustion engines for a variety of applications. Comprehensive engine experiments were conducted in a single-cylinder gasoline direct injection (GDI) engine prototype having a compression ratio of 10.5, for gaining insights into application of mixtures of gasoline and primary alcohols. Performance, emissions, combustion, and particulate characteristics were determined at different engine speeds (1500, 2000, 2500, 3000 rpm), different fuel injection pressures (FIP: 40, 80, 120, 160 bars) and different test fuel blends namely 15% (v/v) butanol, ethanol, and methanol blended with gasoline, respectively (Bu15, E15, and M15) and baseline gasoline at a fixed (optimum) spark timing of 24 deg before top dead center (bTDC). For a majority of operating conditions, gasohols exhibited superior characteristics except minor engine performance penalty. Gasohols therefore emerged as serious candidate as a transitional renewable fuel for utilization in the existing GDI engines, without requirement of any major hardware changes.

Distribution of Two-Stage Direct Injection CNG-Air Mixture near Lean Limit Using CFD

2013 ◽  
Vol 465-466 ◽  
pp. 448-452
Author(s):  
Mas Fawzi ◽  
Bukhari Manshoor ◽  
Yoshiyuki Kidoguchi ◽  
Yuzuru Nada
Keyword(s):  
Fuel Injection ◽  
Direct Injection ◽  
Engine Performance ◽  
Injection Pressure ◽  
Gas Jet ◽  
Exhaust Emission ◽  
Injection Technique ◽  
Injection Timing ◽  
Two Stage ◽  
Lean Burn

Previous work shows that gas-jet ignition with two-stage injection technique is effective to extend lean combustible ranges of CNG engines. In this report, the robustness of the gas-jet ignition with two-stage injection method was investigated purposely to improve the performance of a lean burn direct injection CNG engine. The experiment was conducted using an engine at speed of 900 rpm, fuel-injection-pressure of 3MPa, equivalence ratio at 0.8, and ignition timing at top dead center. The effect of first injection timing on the test engine performance and exhaust emission was analyzed. First injection timings near the gas-jet ignition produced unstable combustion with occurrence of misfires except at a timing which produced distinctively good combustion with low HC and CO emissions. Computational fluid dynamics was used to provide hindsight of the fuel-air mixture distribution that might be the cause of misfires occurrence at certain injection timings.

scholarly journals Particulate emissions from a highly boosted gasoline direct injection engine

2017 ◽  
Vol 19 (3) ◽  
pp. 347-359 ◽  
Author(s):  
Felix Leach ◽  
Richard Stone ◽  
Dave Richardson ◽  
Andrew Lewis ◽  
Sam Akehurst ◽  
...  
Keyword(s):  
Particle Number ◽  
Fuel Injection ◽  
Direct Injection ◽  
Injection Pressure ◽  
Back Pressure ◽  
Gasoline Direct Injection ◽  
Exhaust Gas ◽  
Fuel Injection Pressure ◽  
Gas Recirculation ◽  
Operating Points

Downsized, highly boosted, gasoline direct injection engines are becoming the preferred gasoline engine technology to ensure that increasingly stringent fuel economy and emissions legislation are met. The Ultraboost project engine is a 2.0-L in-line four-cylinder prototype engine, designed to have the same performance as a 5.0-L V8 naturally aspirated engine but with reduced fuel consumption. It is important to examine particle number emissions from such extremely highly boosted engines to ensure that they are capable of meeting current and future emissions legislation. The effect of such high boosting on particle number emissions is reported in this article for a variety of operating points and engine operating parameters. The effect of engine load, air–fuel ratio, fuel injection pressure, fuel injection timing, ignition timing, inlet air temperature, exhaust gas recirculation level, and exhaust back pressure has been investigated. It is shown that particle number emissions increase with increase in cooled, external exhaust gas recirculation and engine load, and decrease with increase in fuel injection pressure and inlet air temperature. Particle number emissions are shown to fall with increased exhaust back pressure, a key parameter for highly boosted engines. The effects of these parameters on the particle size distributions from the engine have also been evaluated. Significant changes to the particle size spectrum emitted from the engine are seen depending on the engine operating point. Operating points with a bias towards very small particle sizes were noted.

Particulate Matter Emission Suppression Strategies in a Turbocharged Gasoline Direct-Injection Engine

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Zhang Ming ◽  
Zhong Jun ◽  
Capelli Stefano ◽  
Lubrano Luigi
Keyword(s):  
Particulate Matter ◽  
Emission Reduction ◽  
Direct Injection ◽  
Injection Pressure ◽  
Particle Emission ◽  
Gasoline Direct Injection ◽  
Injection System ◽  
Dominant Factor ◽  
Injection Timing ◽  
Wide Range

The development process of a down-sized turbocharged gasoline direct-injection (GDI) engine/vehicle was partially introduced with the focus on particulate matter (PM)/particle number (PN) emission reduction. To achieve this goal, the injection system was upgraded to obtain higher injection pressure. Two types of prototype injectors were designed and compared under critical test conditions. Combined numerical and experimental analysis was made to select the right injector in terms of particle emission. With the selected injector, the effect of injection parameters calibration (injection pressure, start of injection (SOI) timing, number of injection pulses, etc.) on PM/PN emission was illustrated. The number of fuel injection pulses, SOI timing, and injection pressure were found playing the leading role in terms of the particle emission suppression. With single-injection strategy, the injection pressure and SOI timing were found to be a dominant factor to reduce particle emission in warm-up condition and cold condition, respectively; a fine combination of injection timing and injection pressure is generally able to decrease up to 50% of PM emission in a wide range of the engine map. While with multiple injection, up to an order of magnitude PM emission reduction can be achieved. Several New European Driving Cycle (NEDC) emission cycles were arranged on a demo vehicle to evaluate the effect of the injection system upgrade and adjusted calibration. This work will provide a guide for the emission control of GDI engines/vehicles fulfilling future emission legislation.

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