scholarly journals Effect of supercharging on improving thermal efficiency and modifying combustion characteristics in lean-burn direct-injection near-zero-emission hydrogen engines

2021 ◽  
Author(s):  
Masakuni Oikawa ◽  
Yoshihisa Kojiya ◽  
Ryota Sato ◽  
Keisuke Goma ◽  
Yasuo Takagi ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Direct Injection ◽  
Combustion Characteristics ◽  
Lean Burn ◽  
Hydrogen Engines ◽  
Zero Emission

Simulation-Aided Development of Prechamber Ignition System for a Lean-Burn Gasoline Direct Injection Motor-Sport Engine

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Muhammed Fayaz Palakunnummal ◽  
Priyadarshi Sahu ◽  
Mark Ellis ◽  
Marouan Nazha
Keyword(s):  
Thermal Efficiency ◽  
Direct Injection ◽  
Fuel Mixture ◽  
Gasoline Direct Injection ◽  
Lean Burn ◽  
Ignition System ◽  
Motor Sport ◽  
Auto Ignition ◽  
Computational Fluid Dynamics Cfd ◽  
Sport Events

Abstract Due to recent regulation changes to restricted fuel usage in various motor-sport events, motor-sport engine manufacturers have started to focus on improving the thermal efficiency and often claim thermal efficiency figures well above equivalent road car engines. With limited fuel allowance, motor-sport engines are operated with a lean air–fuel mixture to benefit from higher cycle efficiency, requiring an ignition system that is suitable for the lean mixture. Prechamber ignition is identified as a promising method to improve lean limit and has the potential to reduce end gas auto-ignition. This paper analyses the full-load performance of a motor-sport lean-burn gasoline direct injection (GDI) engine and a passive prechamber is developed with the aid of a computational fluid dynamics (CFD) tool. The finalized prechamber design benefited in a significant reduction in burn duration, reduced cyclic variation, knock limit extension, and higher performance.

Attainment of High Thermal Efficiency and Near-zero Emissions by Optimizing Injected Spray Configuration in Direct Injection Hydrogen Engines

2019 ◽  
Author(s):  
Masakuni Oikawa ◽  
Yasuo Takagi ◽  
Yuji Mihara ◽  
Nobuyuki Kawahara ◽  
Eiji Tomita ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Direct Injection ◽  
Hydrogen Engines

Numerical Study of the Combustion Characteristics of a Diesel Micro Pilot Ignited DI Gasoline Engine With Turbocharging and Cooled EGR

2013 ◽  
Author(s):  
Yuhua (York) Zhu ◽  
Nameer Salman ◽  
Kevin Freeman ◽  
Ronald Reese ◽  
Zihan Wang ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Numerical Study ◽  
Direct Injection ◽  
Engine Performance ◽  
Combustion Characteristics ◽  
Significant Fraction ◽  
Combustion Stability ◽  
Ignition Source ◽  
Lean Burn ◽  
Load Range

Advanced technologies combining turbocharging, downsizing, direct injection, and cooled EGR are being intensively investigated in order to significantly improve the fuel economy of spark-ignition (SI) gasoline engines. To avoid the occurrence of knock and to improve the thermal efficiency, a significant fraction of EGR is often used. Due to the significant fraction of EGR, the ignition source needs to be enhanced to ensure high combustion stability. In addition to advanced spark-based solutions, diesel micro-pilot (DMP) technology has been proposed in recent years where the diesel fuel replaces the spark-plug as the ignition source. This paper studies the combustion characteristics of a diesel micro pilot ignited gasoline engine, employing direct injection of gasoline and diesel as well as turbocharging and cooled EGR. A multi-dimensional CFD code with a chemical kinetic calculation capability was extensively validated across the engine speed and load range in a previous study [1]. This paper explores the influence of a number of parameters on DMP combustion behavior, including: diesel pilot mass fraction, start of injection (SOI), DMP injection strategy, as well as EGR rate, air/fuel ratio, and DI gasoline/air mixture inhomogeneity. Besides, the comparison of DMP ignited combustion with traditional spark ignited combustion is also made in terms of EGR tolerance, lean burn limit, and DI gasoline air mixture inhomogeneity. Finally, numerical simulations aimed at optimizing both gasoline and diesel injection parameters, as well as EGR rate in order to enhance the engine performance in the DMP combustion mode, are discussed.

Numerical study of the effect of split direct injection on the lean-burn combustion characteristics in a poppet-valve two-stroke gasoline engine at high loads

2020 ◽  
pp. 146808742093240
Author(s):  
Xiao Li ◽  
Bang-Quan He ◽  
Hua Zhao
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Thermal Efficiency ◽  
Direct Injection ◽  
Lean Burn ◽  
Gasoline Engines ◽  
Poppet Valve ◽  
Auto Ignition ◽  
Second Peak

Poppet-valve two-stroke gasoline engines can increase specific power of four-stroke gasoline engines with the same displacement. But knocking combustion may also occur at high loads in two-stroke engines. The application of stratified lean-burn on poppet-valve two-stroke gasoline engines can avoid knocking and increase combustion stability. To investigate the effect of the mixture stratification on lean-burn events at high loads, simulation was conducted in different split direct injection conditions with constant fuel mass when equivalence ratio is 0.625. Results show that most fuel distributes near the center of the cylinder at any second direct injection ratio ( rSOI2). At different rSOI2s, auto-ignition occurs during flame propagation, causing shortened combustion duration. Auto-ignition causes the second peak of the heat release rate. The second peak of the heat release rate first decreases and then increases with increased rSOI2. Indicated mean effective pressure and indicated thermal efficiency increase with increased maximum pressure rise rate. The maximum indicated thermal efficiency of 42% can be reached without knocking combustion at 1500 rpm. The proportion of fuel mass through auto-ignition in the cylinder is an important factor to change the indicated thermal efficiency of a lean-burn engine at high loads.

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