Direct Ignition Research Articles

Progress of Direct Injection and Jet Ignition in Throttle-Controlled Engines

<div class="section abstract"><div class="htmlview paragraph">Direct injection and jet ignition is becoming popular in electrically assisted, turbocharged, F1 engines because of the pressure to reduce fuel consumption. Operation from homogeneous stoichiometric up to lean of stoichiometry stratified about λ = 1.5, occurs with fast combustion of reduced cyclic variability thanks to the enhanced ignition by multiple jets of hot, partially reacting products travelling through the combustion chamber. The fuel consumption has thus been drastically reduced in an engine that is, however, still mostly throttle controlled. The aim of the present paper is to show the advantages of direct injection and jet ignition based on model simulations of the operation of a high-performance throttle-controlled engine featuring rotary valves.</div></div>

Experimental Investigation on Lemongrass Oil Water Emulsion in Low Heat Rejection Direct Ignition Diesel Engine

Abstract This article discusses the experimental investigation of a new biofuel (lemongrass oil) feedstock as an alternative fuel. The subject has not drawn much attention among the fraternity of researchers. So far, an exploration for a new biofuel feedstock has resulted in demonstrating lemongrass oil (LGO) as an alternative energy source. Nickel-chromium-zirconium coating on piston, inlet, and exhaust valves is achieved using a plasma spray method. The coated engine has been tested with a constant level of neat diesel and varying proportions of 5, 10, and 15 percent of LGO–water emulsion; its properties have been analyzed per the ASTM standards. The considered test fuel was experimentally investigated in a single cylinder diesel engine at 1,500 rpm for its performance, combustion, and emission characteristics. Among the different mixtures, a fuel mixture of LGWM1 (LGO of 94 %, water of 5 %, span 80 of 0.5 %, and tween 80 of 0.5 %) profile had similar properties to diesel fuel, resulting in a higher thermal efficiency and a lower hydrocarbon, carbon monoxide emission. However, oxides of nitrogen and carbon dioxide emission were comparatively higher for the test fuel considered. The cylinder pressure and heat release rate curves show a slight increase at the full load condition as compared with diesel fuel. Against the background of continuous fossil fuel depletion, the fuel blend of LGWM1 (LGO of 94 %, water of 5 %, span 80 of 0.5 % and tween 80 of 0.5 %) acts as a promising alternative fuel for further research work.

Effects of thermal barrier coating on the performance, combustion and emission of DI diesel engine powered by biofuel oil–water emulsion

Owing to the fast depletion of fossil fuels and their skyrocketing price due to the tremendous demand, they become imperative to find renewable alternative fuels for diesel engines. Vegetable oils and their mix with diesel in various proportions, called biodiesel, have been found to be very useful in reducing the alarming consumption of fossil fuels. In the present investigation, lemongrass oil is used as an alternative fuel. The availability of lemongrass oil is adequate for Tamil Nadu and Kerala. The coating material chosen is the partially stabilized zirconium because it has low thermal conductivity and high thermal coefficient. The piston top face, cylinder head, inlet valve and the outlet valve are coated. The purpose of low heat rejection engine or coated engine during the combustion process less heat is rejected by insulating materials. In the current work, the experiment is carried out with lemongrass oil with water emulsion and diesel in a four-stroke direct ignition engine with coating and without coating at various load conditions. The diesel engine run with lemongrass oil–water emulsion (94% LGO + 5% water + 1% surfactant), and low heat rejection engine performed better and gave better brake thermal efficiency compared with raw lemongrass oil–water emulsion blend at peak load. Then, the brake-specific fuel consumption of lemongrass oil–water emulsion in the coated engine was 325 (g kW−1 h−1) which was lower than that of lemongrass oil–water emulsion (94% LGO + 5% water + 1% surfactant) in the uncoated engine. Further, combustion parameter of lemongrass oil–water emulsion blend tested in coated engine produced 60 bars in-cylinder pressure, and it was better than lemongrass oil–water emulsion in the uncoated engine. Both the cumulative heat release rate and the heat release rate were in superior range compared with lemongrass oil–water emulsion in the uncoated engine. As regards tailpipe emission, the lemongrass oil–water emulsion blend in the coated engine at peak load delivered a steep reduction in carbon monoxide, hydrocarbon and smoke emission of base diesel blend in the uncoated engine. But, on the contrary, NOx and CO2 emissions were steeply higher compared with the diesel blend that powered the uncoated engine. The entire tested parameters led to the conclusion that lemongrass oil–water emulsion used in the coated diesel engine would be a healthier and economical substitute fuel for hydrocarbonated fuels.

Noise emission research of diesel engine powered with mixture of diesel oil and methyl esters

Generation of noise by reciprocating internal combustion engines is the effect of operation performed by them. Modernization of fuel feeding the power unit makes it possible to limit the emitted sounds preserving the engine’s high operating parameters. The conducted studies concerned comparison of the noise emission generated by a combustion engine fed by diesel oil and a mixture of fatty acids methyl esters (bio component) and the diesel oil in proportions 10%, 30% and 50% of bio component additive, at standard settings of the fuel injection controller. The subject matter of the tests there was the combustion engine with self-ignition of the power of 80 kW with direct ignition common rail, assembled in a vehicle. Adaptation was performed in the selected means of transport making it possible to change quickly the feeding fuel. The test was conducted in the chassis bed. It results from the conducted tests, that the unit fed with the diesel fuel generates noise on the level of 123 dB. Increase of the bio component’s share in the diesel fuel results in the drop of noise emission by approx. 2%. It results from the conducted studies, that the use of the fatty acids methyl esters’ additives to the diesel oil does not decrease the performance of the power unit and contributes to limitation of noise’s emission emitted by that engine.

Potential for onboard hydrogen production in an direct injection ethanol fueled spark ignition engine with EGR

Exhaust gas recirculation, EGR, can be used to produce hydrogen gas (H2) via on board catalytic steam reforming, aiming at controlling emissions and mitigating loss of performance in downsized spark ignition engines. In the most straightforward design, the H2-rich syngas produced by a reactor placed in the EGR line is mixed with the intake air. The EGR and reactor operate in a closed loop, starting in the exhaust and delivering syngas into the intake pipe. Here, a thermodynamic model is developed to evaluate the potential for onboard H2 production in an direct injection ethanol fueled spark ignition engine with EGR. Chemical composition is predicted by assuming equilibrium at engine exhaust and at reactor outlet. Total engine mass flow rate, exhaust temperatures and pressures were adjusted to experimental data. The results indicated a potential to produce a molar concentration of 1% of H2 in the intake mixture, for an engine speed of 5000 rpm. Decreasing engine speed causes a decrease in H2 due to the lower engine exhaust temperature. Hot EGR presents a higher potential for heat recovery, but decreases substantially the heating value of the fuel by recirculation inert gases.

Core-Shell Nanofibrous Materials with High Particulate Matter Removal Efficiencies and Thermally Triggered Flame Retardant Properties.

Dust filtration is a crucial process for industrial waste gas treatment. Great efforts have been devoted to improve the performance of dust filtration filters both in industrial and fundamental research. Conventional air-filtering materials are limited by three key issues: (1) Low filtration efficiency, especially for particulate matter (PM) below 1 μm; (2) large air pressure drops across the filter, which require a high energy input to overcome; and (3) safety hazards such as dust explosions and fires. Here, we have developed a “smart” multifunctional material which can capture PM with high efficiency and an extremely low pressure drop, while possessing a flame retardant design. This multifunctionality is achieved through a core–shell nanofiber design with the polar polymer Nylon-6 as the shell and the flame retardant triphenyl phosphate (TPP) as the core. At 80% optical transmittance, the multifunctional materials showed capture efficiency of 99.00% for PM2.5 and >99.50% for PM10–2.5, with a pressure drop of only 0.25 kPa (0.2% of atmospheric pressure) at a flow rate of 0.5 m s–1. Moreover, during direct ignition tests, the multifunctional materials showed extraordinary flame retardation; the self-extinguishing time of the filtrate-contaminated filter is nearly instantaneous (0 s/g) compared to 150 s/g for unmodified Nylon-6.

The effect of engine emission on canola biodiesel blends with TiO2

ABSTRACTThe role of nanoparticles and nanofluid additives for biodiesel has gained consistent position in the current trend as they contribute to increase the performance of the engine with lower emission. In addition, additives also help to increase the engine reliability and lifespan. In this work, the effects of canola biodiesel blends of 20% proportions with diesel were investigated at 100% of engine load. The fuel is tested in a multi-cylinder water-cooled direct ignition (DI) engine. There are numerous notable works on nanofluid; however, the addition of TiO2 nanoparticle as additive to produce canola biodiesel fuel is very limited. With the addition of the TiO2 nanoparticle on Canola biodiesel blend in the DI engine, the exhaust property of gases such as CO, HC and NOX is reduced. Furthermore, the combustion characteristics of the engine are improved. The canola biodiesel blends also resulted in lower NOx emission as well as low smoke.

An experimental and modeling study to investigate effects of different injection parameters on a direct injection HCCI combustion fueled with ethanol–gasoline fuel blends

In this study, Stochastic Reactor Model (SRM) was used to simulate a direct injection homogenous charge compression ignition (DI-HCCI) engine fueled with ethanol–gasoline blends by two stage direct injection (TSDI) strategies. Performance of the DI-HCCI engine was examined at constant engine speed and high equivalence ratio conditions. TSDI strategies were applied during the intake stroke (first injections) and at the end of the compression stroke (second injections) by using different injection ratios (IR) of E10 and E20 blends. SRM results were compared and validated with the experimental results. Experimental and SRM results showed that the first injection variation does not have significant effect on controlling HCCI combustion while variation of the second injection timing and IR change peak pressure significantly. Therefore, this strategy can be used to control the HCCI combustion.

Effect of Hydrogen Addition and Equivalence Ratio on Swirl Motion of Direct Ignition Engine

Objective: Reducing emissions and better quality of combustion are keen research areas in automobile. For better quality of combustion, modifications of engine features and utilizing novel fuels investigated in many researches. Methods: Hydrogen has very low ignition energy, high flame speed and helps to obtain ultra-lean-burn mixture. In this research work, the hydrogen mole fractions were added in the primary diesel fuel in the ranging from 10% to 90% with each interval of 10 % and varied equivalence ratio from 0.6 to 1.4 to examine the effect on velocity magnitude contour of airfuel particles and swirl motion. Results: All the results were obtained through simulations by using ANSYS Fluent 17 for Internal Combustion (IC) Engines. The addition of hydrogen increases the turbulence intensity of the fuel and leads to better quality of combustion. In addition, the swirl motion decreased because of addition of hydrogen addition and increasing the equivalence ratio. Keywords: Contour Velocity Magnitude, Diesel Fuel, Equivalence Ratio, Hydrogen, and Swirl Ratio.

Effect of Hydrogen Addition and Equivalence Ratio on Tumble Motion of Direct Ignition Engine

Effect of Hydrogen Addition and Equivalence Ratio on Tumble Motion of Direct Ignition Engine

Experimental investigation of the influence of isobutanol addition on engine performance and emissions of a direct ignition diesel engine fuelled by biodiesel blends derived from waste vegetable oil

ABSTRACTBiodiesel has become one of the potential alternative sources to replace diesel. Some of the limitations of biodiesel include high NOx, poor atomization, poor oxidation stability, cold-flow problems, long-term storage problems, etc. Various strategies were discussed to overcome the limitations of biodiesels. Recent research is on effects of fuel additives or fuel composition modification to reformulate the fuel properties. This article is aimed at presenting the experimental investigation of the effects of isobutanol additive on the engine performance and emission characteristics of biodiesel blends derived from waste vegetable oils. The experimental investigation was conducted on a direct injection four-stroke diesel engine with different blends, B10, B20, B30, B10 (10% ISB), B20 (10% ISB), B30 (10% ISB), B10 (20% ISB), B20 (20% ISB) and B30 (20% ISB), and engine performance and emission characteristics are evaluated and discussed.

Stand-alone single- and multi-zone modeling of direct injection homogeneous charge compression ignition (DI-HCCI) combustion engines

Applying the homogeneous charge compression ignition (HCCI) combustion concept leads to advantages regarding fuel economy and particular emissions. One strategy to prepare an in-cylinder homogeneous charge is the very early direct fuel injection referred to as direct-injection (DI) HCCI combustion. In this study, single- and multi-zone models for DI-HCCI engines are developed; a single-zone approach and a novel hybrid approach sequentially applying single- and multi-zone models. Experimental results are compared with model predictions to validate the main assumption of the modeling approach which considers charge homogeneity after fuel entrainment. Results indicate that for DI-HCCI cases, the assumption of neglecting injection-induced stratification is valid. Both approaches show acceptable results which reveals their capability to adequately well capture DI-HCCI combustion engine performance. However, the single-zone approach, as expected, leads to over-prediction of maximum pressure and delivered power. Furthermore, maximum pressure rise rate as an indicator of smooth engine operation is highly over-estimated and combustion phasing is predicted earlier than the experimental measure. Combustion phasing is estimated by single- and multi-zone approaches with average errors of 0.4 and 0.1 crank angle degrees, respectively. Whereas, the power is estimated with average errors of 10 and 1% for single- and multi-zone approaches, respectively.

Numerical analysis of deposit effect on nozzle flow and spray characteristics of GDI injectors

Injector deposit is a common phenomenon for gasoline direct ignition (GDI) engines that greatly affects the spray behavior and consequently the combustion performance and emissions. In this study, the effect of deposit on both the in-nozzle flow dynamics and downstream spray behaviors was numerically investigated. High-resolution X-ray microtomographic scans were performed first to obtain nozzle and deposit morphologies and topology. In-nozzle simulation was then carried out in the Euler-Euler framework with cavitation taken into account by a homogeneous relaxation model (HRM). Finally, the effect of deposit on spray behaviors was evaluated in the Euler-Lagrangian framework, coupled with the in-nozzle simulation results. Results of the nozzle flow simulations highlight that the rough surface of the deposits leads to additional cavitation inception and restricts the flow area, causing mass flow rate losses. Deposits inside the counterbore act as an extension to the inner orifice and constrain the air recirculation. Turbulent levels at the exit of the counterbore are lower for the coked injector due to the reduced air/fuel interaction. Spray simulations have shown that deposits would lead to longer spray penetration, a smaller spray cone angle and larger droplets diameters. Simulation results agree reasonably well with the available experimental data.

Direct ignition tests of brush discharges for explosive methane-air and propane-air gas mixtures

The applied experimental set-up enabling measurements of current waveforms and charge transferred during direct ignition tests with brush discharges, was presented in the paper. Tests were conducted with ignition probe designed according to the IEC 60079-32-2 Standard for methane-air gas and propane-air gas mixtures. In the experiment 100 trials were conducted using sample consisted of fluorinated polyethylene. The sample was rubbed with sheep felt cloth. Charge transfer measured rates ranged from 50 nC to 260 nC and the current peak magnitude ranged from 0.5 A to 3.5 A. Magnitude of the current peak as a function of the transferred charge, recorded in the experiment, was presented in the paper. Two regions can be distinguished on the Q = f(dQ/dt) characteristic. There is a region where discharges do not cause ignition and the other one, where the results indicate ignition of gas mixture.

Ignition of a cloud of dry powder using super brush discharges

Ignition of a cloud of dry powder is a major concern in the field of industrial process safety. The different types of discharges are already defined (spark discharges, brush discharges, propagating discharges, cone discharges, corona discharges) such as their ignition properties in a gas or a dust atmosphere. For example, it is known that a classic brush discharge cannot ignite a cloud of dry flammable dust [6,13]. Glor and Schwenzfeuer performed direct ignition tests using brush discharges and defined that even if the energy released by this kind of discharge equaled the one of a spark, the power released by the brush discharge is too low to trigger an ignition.However, some doubts remained for super brush discharges. A brush discharge as a super brush discharge occurs between a charged insulating object and a conductive electrode. The main difference lies in the surface charge density reached on the insulator that is much higher for a super brush discharge than for a brush discharge. A high charge density can be reached for example using pipes of polyethylene individually charged by tribo-charging piled one above another. Such a configuration was evocated by Lüttgens [12] and tested by Larsen [11] who performed direct ignition tests in oxygen enriched atmospheres.This study is relevant with the actual safety problems since pharmaceutical and chemical powders are well known to generate electrostatic charges during their transport or handling and since the same configuration of independent polyethylene fibers can be found in flexible bulk containers that are one of the most common solutions to package this kind of powder.This paper presents the experimental set-up and the results of direct ignition tests performed with a polyethylene wax whose MIE is lower than 1 mJ at ambient conditions. The electric field reached at 1 m and the charge transfer were also registered and are described. Finally, numerical simulations are carried out to define the original surface charge density in order to help to understand the phenomenology of this discharge and its frequency of occurrence in industry.

Interaction between flaming and smouldering in hot-particle ignition of forest fuels and effects of moisture and wind

Ignition of natural fuels by hot metal particles from powerlines, welding and mechanical processes may initiate wildfires. In this work, a hot steel spherical particle (6–14 mm and 600–1100°C) was dropped onto pine needles with a fuel moisture content (FMC) of 6–32% and wind speed of 0–4 m s–1. Several ignition phenomena including direct flaming, smouldering and smouldering-to-flaming transition were observed. The critical particle temperature for sustained ignition was found to decrease with the particle size (d) and increase with FMC as (°C), and the maximum heating efficiency of particle was found to be . As the particle size increases, the influence of FMC becomes weaker. The flaming ignition delay times for both direct flaming and smouldering-to-flaming transition were measured, and decreased with particle temperature and wind speed, but increased with FMC. The proposed heat-transfer analysis explains the ignition limit and delay time, and suggests that the hot particle acts as both heating and pilot sources like a small flame for direct flaming ignition, but only acts as a heating source for smouldering. This study deepens the fundamental understanding of hot-particle ignition, and may help provide a first step to understanding the mechanism behind firebrand ignition.

The influences of moisture on particle ignition behavior of Chinese and Indonesian lignite coals in hot air flow

The effect of moisture content on ignition and combustion behavior of Chinese (HL) and Indonesian (YN) lignite were investigated. Particles with a size range of 75–105μm with different moisture contents were injected in a bench-scale, electrically heated transparent reactor and the combustion of individual particles was observed with a high-resolution high-speed camera. Direct ignition observations indicated that most of the HL lignite particles underwent extensive fragmentation during ignition. Fragmentation was attributed to the explosive diffusion of volatiles and water vapor to the particle surface as a result of fast heating rate. Fragmentation reduced the particle size and increased the possibility of heterogeneous ignition of individual fragments. YN lignite particles on the other hand, underwent one-mode whole particle ignition upon heating. Higher moisture content caused a significant ignition delay in both lignite samples. 10% and 20% moisture in lignite samples resulted in around 83 and 160ms delay in ignition for both coals. Higher intensity of fragmentation of HL particles during combustion compared to YN lignite resulted in shorter total particle combustion time at higher moisture contents. The findings of this study advanced the knowledge of the effects of moisture on ignition and combustion of low-rank coals.

Performance and Emission Characteristics of Diesel and Jatropha Oil Blends in a Direct Injection Variable Compression Ratio Ignition Engine

Performance and Emission Characteristics of Diesel and Jatropha Oil Blends in a Direct Injection Variable Compression Ratio Ignition Engine

Combustion noise analysis of partially premixed combustion concept using gasoline fuel in a 2-stroke engine

In the last decade, different advanced combustion concepts based on generating totally or partially premixed conditions have been investigated in CI (compression ignition) engines with the aim of achieving lower NOx (nitrous oxides) and soot emissions. Most of the drawbacks inherent to this type of combustions, such as the combustion phasing control or combustion stability, can be mitigated by combining the PPC (Partially Premixed Combustion) concept fueled by gasoline and a small 2-stroke HSDI (high speed direct ignition) engine. However, combustion noise issue remains unsolved while it is a critical aspect due to its strong influence in the customer purchasing decision and compliance of more stringent regulations. In this work, an analysis of the combustion noise generated by PPC combustion concept is performed in order to identify the most influential parameters and to define key paths for controlling the noise level. In addition, 3D CFD (Computational Fluid Dynamics) simulations have been performed to further understand the combustion noise generation mechanisms. Results evidence how the strong impact of the maximum pressure time-derivative achieved during combustion process renders all other sources of noise generation irrelevant. The trade-off between combustion noise and combustion efficiency of this PPC concept has been confirmed, while the intrinsic relation between such parameters and the engine efficiency has been also evaluated.

Ignition of a Cloud of Dry Powder Using Super Brush Discharges

Ignition of a cloud of dry powder is a major concern in the field of industrial process safety. The different types of discharges are already defined (spark discharges, brush discharges, propagating discharges, cone discharges, corona discharges) such as their ignition properties in a gas or a dust atmosphere. For example, it is known that a classic brush discharge cannot ignite a cloud of dry flammable dust (Glor & Schwenzfeuer, 2005; Schwenzfeuer & Glor, 2001). Glor and Schwenzfeuer performed direct ignition tests using brush discharges and defined that even if the energy released by this kind of discharge equaled the one of a spark, the power released by the brush discharge is too low to trigger an ignition.However, some doubts remained for super brush discharges. A brush discharge as a super brush discharge occurs between a charged insulating object and a conductive electrode. The main difference lies in the surface charge density reached on the insulator that is much higher for a super brush discharge than for a brush discharge. A high charge density can be reached for example using pipes of polyethylene individually charged by tribo-charging piled one above another. Such a configuration was evocated by Luttgens (Luttgens& Wilson, 1997) and tested by Larsen (Larsen, Hagen, & van Wingerden, 2001) who performed direct ignition tests in oxygen enriched atmospheres.This study is relevant with the actual safety problems since pharmaceutical and chemical powders are well known to generate electrostatic charges during their transport or handling and since the same configuration of independent polyethylene fibers can be found in flexible bulk containers that are one of the most common solutions to package this kind of powder.This paper presents the experimental set-up and the results of direct ignition tests performed with a polyethylene wax whose MIE is lower than 1mJ at ambient conditions. The electric field reached at 1 meter and the charge transfer were also registered and are described. Finally, numerical simulations are carried out to define the original surface charge density in order to help to understand the phenomenology of this discharge and its frequency of occurrence in industry.