scholarly journals CFD-Guided Evaluation of Spark-Assisted Gasoline Compression Ignition for Cold Idle Operation

2021 ◽  
Vol 13 (23) ◽  
pp. 13096
Author(s):  
Le Zhao ◽  
Yu Zhang ◽  
Yuanjiang Pei ◽  
Anqi Zhang ◽  
Muhsin M Ameen
Keyword(s):  
Fuel Injection ◽  
Design Parameters ◽  
Injection Timing ◽  
Discharge Process ◽  
Compression Ignition ◽  
Kernel Development ◽  
Local Flow ◽  
Flame Kernel ◽  
Fuel Stratification ◽  
Spark Gap

A closed-cycle, three-dimensional (3D) computational fluid dynamics (CFD) analysis campaign was conducted to evaluate the performance of using spark plugs to assist gasoline compression ignition (GCI) combustion during cold idle operations. A conventional spark plug using single-sided J-strap design was put at a location on the cylinder head to facilitate spray-guided spark assistance. Ignition was modeled with an L-type energy distribution to depict the breakdown and the arc-to-glow phases during the energy discharge process. Several key design parameters were investigated, including injector clocking, number of nozzle holes, spray inclusion angle, number of fuel injections, fuel split ratio, and fuel injection timings. The study emphasized the region around the spark gap, focusing on flame kernel formation and development and local equivalence ratio distribution. Flame kernel development and the ignition process were found to correlate strongly with the fuel stratification and the flow velocity near the spark gap. The analysis results showed that the flame kernel development followed the direction of the local flow field. In addition, the local fuel stratification notably influenced early-stage flame kernel development due to varying injection spray patterns and the fuel injection strategies. Among these design parameters, the number of nozzle holes and fuel injection timing had the most significant effects on the engine combustion performance.

Fuel Stratification and Partially Premixed Combustion With Neat n-Butanol in a Compression Ignition Engine

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Shouvik Dev ◽  
Tongyang Gao ◽  
Xiao Yu ◽  
Mark Ives ◽  
Ming Zheng
Keyword(s):  
Fuel Injection ◽  
Direct Injection ◽  
Premixed Combustion ◽  
Injection Timing ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Fuel Stratification ◽  
Partially Premixed Combustion ◽  
Partially Premixed ◽  
Ci Engines

Homogeneous charge compression ignition (HCCI) has been considered as an ideal combustion mode for compression ignition (CI) engines due to its superb thermal efficiency and low emissions of nitrogen oxides (NOx) and particulate matter. However, a challenge that limits practical applications of HCCI is the lack of control over the combustion rate. Fuel stratification and partially premixed combustion (PPC) have considerably improved the control over the heat release profile with modulations of the ratio between premixed fuel and directly injected fuel, as well as injection timing for ignition initiation. It leverages the advantages of both conventional direct injection compression ignition and HCCI. In this study, neat n-butanol is employed to generate the fuel stratification and PPC in a single cylinder CI engine. A fuel such as n-butanol can provide additional benefits of even lower emissions and can potentially lead to a reduced carbon footprint and improved energy security if produced appropriately from biomass sources. Intake port fuel injection (PFI) of neat n-butanol is used for the delivery of the premixed fuel, while the direct injection (DI) of neat n-butanol is applied to generate the fuel stratification. Effects of PFI-DI fuel ratio, DI timing, and intake pressure on the combustion are studied in detail. Different conditions are identified at which clean and efficient combustion can be achieved at a baseline load of 6 bar IMEP. An extended load of 14 bar IMEP is demonstrated using stratified combustion with combustion phasing control.

Factors Affecting Performance of Dual Fuel Compression Ignition Engines

2013 ◽  
Vol 388 ◽  
pp. 217-222
Author(s):  
Mohamed Mustafa Ali ◽  
Sabir Mohamed Salih
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Direct Injection ◽  
Injection System ◽  
Dual Fuel ◽  
Injection Timing ◽  
Compression Ignition ◽  
Factors Affecting

Compression Ignition Diesel Engine use Diesel as conventional fuel. This has proven to be the most economical source of prime mover in medium and heavy duty loads for both stationary and mobile applications. Performance enhancements have been implemented to optimize fuel consumption and increase thermal efficiency as well as lowering exhaust emissions on these engines. Recently dual fueling of Diesel engines has been found one of the means to achieve these goals. Different types of fuels are tried to displace some of the diesel fuel consumption. This study is made to identify the most favorable conditions for dual fuel mode of operation using Diesel as main fuel and Gasoline as a combustion improver. A single cylinder naturally aspirated air cooled 0.4 liter direct injection diesel engine is used. Diesel is injected by the normal fuel injection system, while Gasoline is carbureted with air using a simple single jet carburetor mounted at the air intake. The engine has been operated at constant speed of 3000 rpm and the load was varied. Different Gasoline to air mixture strengths investigated, and diesel injection timing is also varied. The optimum setting of the engine has been defined which increased the thermal efficiency, reduced the NOx % and HC%.

Analysis of Compression-Ignition Engine Design Concerning Engine Structural Loading Capacity

2004 ◽  
Author(s):  
Gong Chen
Keyword(s):  
Thermal Loading ◽  
Fuel Injection ◽  
Fuel Efficiency ◽  
Design Parameters ◽  
Analytical Prediction ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Exhaust Temperature ◽  
High Fuel Efficiency ◽  
Structural Loading

Present-day high-power compression-ignition engines are required in design not only to achieve a targeted high fuel efficiency, but also to meet regulated exhaust emissions standards. This paper investigates the effects of the in-cylinder combustion related design parameters, including cylinder compression ratio, fuel injection-start timing, and the amount of cylinder air charge, on engine performances and emissions as the engine structure-loading allowance is specified. Thereby the determination of those parameters to optimize the engine overall performances without exceeding the allowances in engine mechanical and thermal loading can be achieved. An enhanced understanding of those design parameters associated with the engine structural loading parameters, such as the cylinder peak firing pressure and exhaust temperature, is studied. The analytical prediction of the trade-off between those parameters with peak firing pressure contained is modeled and developed.

scholarly journals Gasoline Compression Ignition (GCI) on a Light-Duty Multi-Cylinder Engine Using a Wide Range of Fuel Reactivities and Heavy Fuel Stratification

2020 ◽  
Author(s):  
Adam B. Dempsey ◽  
Scott Curran ◽  
Robert Wagner ◽  
William Cannella ◽  
Andrew Ickes
Keyword(s):  
Fuel Injection ◽  
Combustion Process ◽  
Engine Performance ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Cycle Basis ◽  
Fuel Stratification ◽  
Light Duty ◽  
Wide Range ◽  
Research Studies

Abstract Many research studies have focused on utilizing gasoline in modern compression ignition engines to reduce emissions and improve efficiency. Collectively, this combustion mode has become known as gasoline compression ignition (GCI). One of the biggest challenges with GCI operation is maintaining control over the combustion process through the fuel injection strategy, such that the engine can be controlled on a cycle-by-cycle basis. Research studies have investigated a wide variety of GCI injection strategies (i.e., fuel stratification levels) to maintain control over the heat release rate while achieving low temperature combustion (LTC). This work shows that at loads relevant to light-duty engines, partial fuel stratification (PFS) with gasoline provides very little controllability over the timing of combustion. On the contrary, heavy fuel stratification (HFS) provides very linear and pronounced control over the timing of combustion. However, the HFS strategy has challenges achieving LTC operation due to the air handling burdens associated with the high EGR rates that are required to reduce NOx emissions to near zero levels. In this work, a wide variety of gasoline fuel reactivities (octane numbers ranging from < 40 to 87) were investigated to understand the engine performance and emissions of HFS-GCI operation on a multi-cylinder light-duty engine. The results indicate that over an EGR sweep at 4 bar BMEP, the gasoline fuels can achieve LTC operation with ultra-low NOx and soot emissions, while conventional diesel combustion (CDC) is unable to simultaneously achieve low NOx and soot. At 10 bar BMEP, all the gasoline fuels were compared to diesel, but using mixing controlled combustion and not LTC.

Effects of fuel injection parameters on premixed charge compression ignition combustion and emission characteristics in a medium-duty compression ignition diesel engine

2019 ◽  
pp. 146808741986701 ◽  
Author(s):  
Santiago Molina ◽  
Antonio García ◽  
Javier Monsalve-Serrano ◽  
David Villalta
Keyword(s):  
Diesel Engine ◽  
Fuel Injection ◽  
Transport Sector ◽  
Injection Timing ◽  
Compression Ignition ◽  
Injection Strategy ◽  
Low Load ◽  
Main Injection ◽  
Compression Ignition Combustion ◽  
The Impact

From the different power plants, the compression ignition diesel engines are considered the best alternative to be used in the transport sector due to its high efficiency. However, the current emission standards impose drastic reductions for the main pollutants, that is, NO x and soot, emitted by this type of engines. To accomplish with these restrictions, alternative combustion concepts as the premixed charge compression ignition are being investigated nowadays. The objective of this work is to evaluate the impact of different fuel injection strategies on the combustion performance and engine-out emissions of the premixed charge compression ignition combustion regime. For that, experimental measurements were carried out in a single-cylinder medium-duty compression ignition diesel engine at low-load operation. Different engine parameters as the injection pattern timing, main injection timing and main injection fuel quantity were sweep. The best injection strategy was determined by means of a methodology based on the evaluation of a merit function. The results suggest that the best injection strategy for the low-load premixed charge compression ignition operating condition investigated implies using a high injection pressure and a triple-injection event with a delayed main injection with almost 15% of the total fuel mass injected.

A Study on the Performance and Emissions Characteristics of a DI Compression Ignition Engine Operated With LPG and DTBP Blending Fuels

2011 ◽  
Author(s):  
Hoin Kang ◽  
Jerald A. Caton ◽  
Seangwock Lee ◽  
Seokhwan Lee ◽  
Seungmook Oh
Keyword(s):  
Combustion Chamber ◽  
Fuel Injection ◽  
Ambient Pressure ◽  
Injection Pressure ◽  
Chamber Pressure ◽  
Injection Timing ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Bench Tests ◽  
Fuel Injection Pressure

LPG (Liquefied Petroleum Gas) has been widely used as an alternative fuel for gasoline and diesel vehicles in light of clean fuel and diversity of energy resources. But conventional LPG vehicles using carburetors or MPI fuel injection systems can’t satisfy the emissions regulations and CO2 targets of the future. Therefore, it is essential to develop LPG engines of spark ignition or compression ignition type such that LPG fuel is directly injected into the combustion chamber under high pressure. A compression ignition engine using LPG is the ideal engine with many advantages of fuel economy, heat efficiency and low CO2, even though it is difficult to develop due to the unique properties of LPG. This paper reports on numerical and experimental studies related to LPG fuel for a compression ignition engine. The numerical analysis is conducted to study the combustion chamber shape with CATIA and to analyze the spray and fluid behaviors with FLUENT for diesel and LPG (n-butane 100%) fuels. In one experimental study, a constant volume chamber is used to observe the spray formation for the chamber pressure 0 to 3MPa and to analyze the flame process, P-V diagram, heat release rate and emissions through the combustion of LPG fuel with the cetane additive DTBP (Di-tert-butyl peroxide) 5 to 15 wt% at 25MPa of fuel injection pressure. In engine bench tests, experiments were performed to find the optimum injection timing, lambda, COV and emissions for the LPG fuel with the cetane additive DTBP 5 to 15 wt% at 25MPa fuel injection pressure and 1500 rpm. The penetration distance of LPG (n-butane 100%) was shorter than that of diesel fuel and LPG was sensitive to the chamber pressure. The ignition delay was in inverse proportion to the ambient pressure linearly. In the engine bench tests, the optimum injection timing of the test engine to the LPG fuel with DTBP 15 wt% was about BTDC 12° CA at all loads and 1500 rpm. An increasing of DTBP blending ratio caused the promotion of flame and fast burn and this lead to reduce HC and CO emissions, on the other hand, to increase NOx and CO2 emissions.

scholarly journals Effect of Premixed Fuel Preparation for Partially Premixed Combustion With a Low Octane Gasoline on a Light-Duty Multicylinder Compression Ignition Engine

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Adam B. Dempsey ◽  
Scott Curran ◽  
Robert Wagner ◽  
William Cannella
Keyword(s):  
High Pressure ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Premixed Combustion ◽  
Injection System ◽  
Injection Timing ◽  
Pilot Injection ◽  
Compression Ignition ◽  
Partially Premixed Combustion ◽  
Injection Strategies

Gasoline compression ignition (GCI) concepts with the majority of the fuel being introduced early in the cycle are known as partially premixed combustion (PPC). Previous research on single- and multicylinder engines has shown that PPC has the potential for high thermal efficiency with low NOx and soot emissions. A variety of fuel injection strategies have been proposed in the literature. These injection strategies aim to create a partially stratified charge to simultaneously reduce NOx and soot emissions while maintaining some level of control over the combustion process through the fuel delivery system. The impact of the direct injection (DI) strategy to create a premixed charge of fuel and air has not previously been explored, and its impact on engine efficiency and emissions is not well understood. This paper explores the effect of sweeping the direct injected pilot timing from −91 deg to −324 deg ATDC, which is just after the exhaust valve closes (EVCs) for the engine used in this study. During the sweep, the pilot injection consistently contained 65% of the total fuel (based on command duration ratio), and the main injection timing was adjusted slightly to maintain combustion phasing near top dead center. A modern four cylinder, 1.9 l diesel engine with a variable geometry turbocharger (VGT), high pressure common rail injection system, wide included angle injectors, and variable swirl actuations was used in this study. The pistons were modified to an open bowl configuration suitable for highly premixed combustion modes. The stock diesel injection system was unmodified, and the gasoline fuel was doped with a lubricity additive to protect the high pressure fuel pump and the injectors. The study was conducted at a fixed speed/load condition of 2000 rpm and 4.0 bar brake mean effective pressure (BMEP). The pilot injection timing sweep was conducted at different intake manifold pressures, swirl levels, and fuel injection pressures. The gasoline used in this study has relatively high fuel reactivity with a research octane number of 68. The results of this experimental campaign indicate that the highest brake thermal efficiency (BTE) and lowest emissions are achieved simultaneously with the earliest pilot injection timings (i.e., during the intake stroke).

Numerical assessment of ozone addition potential in direct injection compression ignition engines

2020 ◽  
pp. 146808742097355
Author(s):  
Vincent Giuffrida ◽  
Michele Bardi ◽  
Mickael Matrat ◽  
Anthony Robert ◽  
Guillaume Pilla
Keyword(s):  
Cfd Simulation ◽  
Fuel Injection ◽  
Direct Injection ◽  
High Reactivity ◽  
Experimental Results ◽  
Injection Timing ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Compression Stroke ◽  
The Impact

This paper aims at taking into account the chemistry of O3 in a 3D CFD simulation of compression ignition engine with Diesel type combustion for low load operating points. The methodology developed in this work includes 0D homogeneous reactors simulations, 3D RANS simulations and validation regarding experimental results. The 0D simulations were needed to take into account O3 reactions during the compression stroke because of the high reactivity of O3 with NO and dissociation at high temperature. The values found in these simulations were used as an input in the 3D model to match the correct O3 concentration at fuel injection timing. The 3D simulations were performed using CONVERGETM with a RANS approach. Simulations reproduce the compression/expansion stroke after the intake valve closure to focus on the impact of O3 on the fuel auto ignition. The comparison between numerical and experimental results demonstrates that the proposed methodology is able to capture correctly the impact of O3 addition on ignition delay and on heat release. Moreover, the analysis of the data enables to better understand the fundamental processes driving O3 impact in a CI engine. In particular, using 0D simulations, the plateau effect observed experimentally when increasing O3 concentration is attributed to O3 thermal decomposition and reaction with NO during the compression stroke. Also, 3D CFD results showed that O3 impact is observed mainly during LTHR phase and does not affect the topology and the propagation of the flame inside the combustion chamber.

Numerical Investigation of the Impact of Spray – Bowl Interaction on Thermal Efficiency of a Gasoline Compression Ignition Engine

2021 ◽  
Author(s):  
Srinivasa Krishna Addepalli ◽  
Michael Pamminger ◽  
Riccardo Scarcelli ◽  
Thomas Wallner
Keyword(s):  
Thermal Efficiency ◽  
Fuel Injection ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Design Parameters ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Baseline Design ◽  
Piston Bowl ◽  
The Impact

Abstract Gasoline compression ignition (GCI) is a promising way to achieve high thermal efficiency and low emissions while leveraging conventional diesel engine hardware. GCI is a partially premixed combustion concept, which derives its superiority from good volatility and long ignition delay of gasoline-like fuels. The present study investigates the interaction between the piston bowl and the spray plume of a compression ignition engine that operates with a late fuel injection strategy using computational fluid dynamics (CFD) analysis. Simulations were carried out on a single cylinder of a multi-cylinder heavy-duty compression ignition engine. The engine operates at a speed of 1038 rev/min., and a compression ratio of 17. Incylinder turbulence was modelled using RNG k-ε model and the fuel spray break up was modelled using KH-RT model. A reduced chemical kinetic mechanism was used to model combustion chemistry. After validating the combustion and performance characteristics of the baseline piston against experimental results, several new piston bowl designs were generated using CAESES. Full cycle engine simulations for four selected bowl profiles were carried out. The results compare the spray-bowl interaction of the new piston bowl designs with the baseline design. It was found that the lip location and center depth of the bowl profile are the critical design parameters that influence the air utilization and heat transfer losses. The impact of spray-bowl interaction on thermal efficiency of the engine is investigated.

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