Dual Injection System Research Articles

Combustion and emission characteristics of a dual injection system applied to a DISI engine

Concerns about environmental pollution and energy shortages have increased worldwide. One approach to reduce CO2 emissions from gasoline engines is to achieve stratified charge combustion with various injection ratios using port fuel injection (PFI) and direct injection. The combustion and emission characteristics of a 4-valve direct injection spark ignition (DISI) engine equipped with a dual injection system were investigated while the injection ratio was varied. When the direct injection ratio increased, the lean limit A/F was extended. This suggests that the dual injection gasoline engine with both PFI and direct injection can meet severe vehicle emission and fuel economy requirements. The dual injection system had higher combustion pressure than that of either a conventional or direct injection systems. Therefore, the engine power of a dual injection DISI engine would be higher than that of a single injection DISI engine. However, NO emissions increased compared with the emission levels in both PFI and DISI systems.

실험계획법에 의한 가솔린 GDI+MPI 엔진의 연비 및 성능향상 관점에서의 운전영역별 연료분사 전략에 관한 연구

The gasoline direct injection (GDI) system is considerably spreading in automotive market due to its advantages. Nevertheless, since GDI system emit higher particle matter (PM) due to its combustion characteristics, it is difficult to meet strengthened emission regulation in near future. For this reason, a combined GDI with MPI system, so-called, dual injection (DUI) system is being investigated as a supplemental measure for the GDI system. This paper focused on power and fuel consumption effect by injection mode strategy of DUI system in part load and idle engine operating condition. In this study, port fuel injectors are installed on 2.4 liters GDI production engine in order to realize DUI system. And, at each injection mode, DOE (design of experiment) method is used to optimize engine control parameters such as dual injection ratio, start of injection timing, end of injection timing, CAM position and so on. As a consequence, DUI mode shows slightly better or equivalent fuel efficiency compared to conventional GDI engine on 9 points fuel economy mode as well as MPI mode shows less fuel consumption than GDI mode during idle operation. Furthermore, DUI system shows improvement potential of maximum 2.0% fuel consumption and 1.1% performance compared to GDI system in WOT operating condition.

Wall-wetting model based method for air-fuel ratio transient control in gasoline engines with dual injection system

Modern gasoline engines with dual injection system improve combustion efficiency by using the two injection commands simultaneously. Due to the different dynamics in the two injection paths, the transient air-fuel ratio (A/F) performance when the injection authority is changed remarkably affects the emission performance of the engine system. For this kind of engines, this paper proposes a model-based design approach that gives a dynamic feedforward compensation for achieving good transient A/F performance. Actually, this work centers on discussing the mean-value model parameters for characterizing the wall-wetting phenomenon when the port injection authority is changed under different engine operation conditions. Moreover, from the view of practice, taking into account the event-based physics of the engine system, significant calibration for the model parameters that are employed for achieving the feedforward compensation is investigated experimentally. Finally, experimental validation results demonstrate the improvement of the transient A/F performance by using the control scheme.

Performance, combustion and emission characteristics of a spark-ignition engine with simultaneous injection of n-butanol and gasoline in comparison to blended butanol and gasoline

SUMMARY Simultaneous injection of n-butanol and gasoline through a new system of two injectors directing the sprays towards the back of the intake valve in a spark-ignition engine was tried in lieu of injecting a blend of these fuels through a single injector. This system avoids the problem of phase separation, which is generally faced during the use of alcohol-gasoline blends. Experiments were conducted on a spark-ignition engine with this dual injection system using a fuel ratio of 1:1 (B50S) on the mass basis. High-speed photographs indicated that the sprays from the injectors did not interfere till they reached the intake valve. Comparisons were made with pre-blended butanol-gasoline (B50) and neat (100%) gasoline at the best spark timing. All injection and spark parameters were controlled using a real time engine controller. Neat n-butanol (B100) was superior only near full throttle with improved efficiency of the engine of about 1.2% (absolute). Heat release rates were observed to be higher and more advanced with B100 at wide open throttle. However, a reverse of this trend was observed at the throttle position of 15%. NO emission was also lower by 30% with B100 at wide open throttle as compared with gasoline. However, a small increase in carbon monoxide (CO) levels was observed because of lower post combustion temperatures as compared with gasoline and B50S. Simultaneous injection reduced hydrocarbon (HC) emissions by 13% to 50% as compared with B50 (blended fuel). HC emissions with gasoline and B50S were similar. Nitric oxide (NO) emission was lower with B50S as compared with gasoline; however it was higher than B50 because of better combustion. On the whole, the developed dual injection system was superior to the conventional method of blending in terms of performance, emissions and ability to change the fuel ratio as needed. B50S is suitable at all throttle positions, whereas B100 shows benefits at full throttle conditions. Copyright © 2013 John Wiley & Sons, Ltd.

Effective utilisation of butanol along with gasoline in a spark ignition engine through a dual injection system

In spark ignition engines fuelled by alcohol gasoline blends, the proportion of the two fuels has to be varied according to the operating condition. Further high amounts of alcohol cannot be blended with gasoline because the two phases can separate under certain conditions. In this work a dual injection system, wherein n-butanol and gasoline can be injected separately in any ratio has been employed in a spark ignition engine. The objective is to determine the most suitable amounts of n-butanol and gasoline to be used at different operating conditions of a four stroke spark ignition engine when these fuels are simultaneously injected into the intake manifold using this dual injection system. Experiments are conducted at different fuel ratios and throttle positions at an equivalence ratio of 1. The system results in good vaporization of the fuels even at low load conditions because the fuel jets are aligned to hit different portions of the intake valve. Results indicate that with proper selection of the fuel ratio significant reduction in HC emissions can be achieved as compared to operation on neat gasoline. Up to 60% of n-butanol could be used at 15% throttle while up to 80% could be used at 25% throttle. These proportions are higher than what have been achieved by pre-blending these fuels. The possibility of using high amounts of n-butanol reduced the tendency to knock. Hence, with the dual injection system n-butanol can be effectively used along with gasoline.

Influence of nanostructured ZrO2 additions on the wear resistance of Ni-based alloy coatings deposited by APS process

In the present investigation, the influence of the addition of nanostructure zirconia particles on the microstructure, micro-hardness and wear performance of a Ni-based alloy (Colmonoy 88) deposited by atmospheric plasma spraying (APS) on low carbon steel has been reported. Two different procedures were tested: (i) spraying powders of Colmonoy 88 and zirconia mixed by mechanical alloying and (ii) spraying powders separately using a dual powder injection system available at the APS equipment. The microstructure and the mechanical properties of coatings were characterized by scanning electron microscopy/energy dispersive X-ray analysis (SEM-EDS), X-ray diffraction (XRD) and micro-hardness measurements. The tribological properties were evaluated at room temperature in reciprocating sliding wear equipment. The results indicate that the as-sprayed modified coatings were mainly composed by Ni, Ni–Cr–Fe, Cr23C6, Cr5B3, and tetragonal zirconia. Evenly distribution of zirconia can be seen in the coatings produced by powders prepared by mechanical alloying, while dispersive ones can be seen in the other case. Hardness and wear resistance of coatings is increased with nanostructured zirconia additions, while their friction coefficient is decreased. Coatings produced with mechanical alloying show the highest wear resistance of all tested coatings. Nanostructured ZrO2 coating displays the worst wear resistance.

Liquid butane as an alternative fuel for diesel oil burners

The experimental tests performed to study the combustion process of liquid butane employing a diesel oil burner are presented. For these tests, a dual pumping and injection system was designed to operate with pressures varying from 0.8 to 2.0MPa. Five distinctive cases were tested for each fuel, obtaining a complete characterization of the combustion processes in comparable conditions. Flame geometries, temperatures and the main chemical products of the combustion process were recorded experimentally for both liquid butane and diesel oil. It was observed that liquid butane flames present elongated conical shapes, with low radiation cyan color at the base position, followed by a higher radiation zone in the core and flame front positions. Also, the temperatures and NOx concentrations of liquid butane flames are lower than those of diesel oil flames. In general, it is feasible to modify the combustion technology of diesel oil burners to use liquid butane as an alternative fuel.

직접분사식 가솔린엔진의 분사 비율에 따른 연소특성에 관한 연구

Recently, the important issues of gasoline engine are to reduce the fuel consumption and emission. Thus, many researchers are studying the technology to solve these problems. One approach of these issues is to achieve homogeneous charge combustion and stratified change combustion with various injection strategy. In this study, the combustion characteristics of DISI engine accrding to injection strategy were examined. The effect of injection timing on lean limit A/F were investigated using dual DISI single cylinder. The results show that the engine operation region of dual DISI type engine is larger than that of PFI and DISI type engine cases. Especially, late injection is very effective to extend the operation region more than any other injection timings. In addition, the results show that when the DISI injection ratio is increase, leam limit A/F is improved. It means that the dual injection system car meet with emission regulations and reduce the fuel consumption. Also, combustion pressure of dual injection system is much higher than PFI and DISI injection.

Analysis of dual secondary injection for thrust vectoring

PurposeThe purpose of this paper is to analyze the flowfield structure and performance of dual secondary injection system for thrust vectoring in a convergent‐divergent nozzle and to compare it with a single secondary injection system.Design/methodology/approachDual secondary injection for thrust vectoring in a convergent‐divergent nozzle is studied by solving three‐dimensional Reynolds‐averaged Navier‐Stokes equations by the means of Fluent. Realizable k‐ε turbulent model with enhanced wall‐treatment approach is used for viscous model. Density‐based solver and explicit scheme are employed in the computational model. In order to study the effect of injection location on the flowfield, distance between ports is considered as the key variable.FindingsResults show that under some circumstances, dual secondary injection system is more effective than a single injection system with the same mass flow rate. The study shows that when the distance between two ports is 8.5 times of the injection port's diameter (or more) and in the same time the first injection port is at least 1 throat diameter far from the nozzle throat, this system will show a better performance. In addition, this system reduces the probability of bow shock impingement to the opposite wall and consequently, the side force production has less limitation.Practical implicationsDual secondary injection for thrust vector control (SITVC) needs less secondary flow and therefore it makes less reduction in the primary thrust. It means that for a specific primary thrust, less mass fuel is needed which makes it more economic regarding the traditional SITVC systems.Originality/valueThe paper's value lies in using a three‐dimensional model to study the effect of two ports distance on SITVC performance and comparison among the performance of dual and single injections when there is an impingement.

Bistability in an injection locked two color laser with dual injection

A two color Fabry-Pérot laser subjected to optical injection in both modes is examined experimentally and theoretically. The theoretical analysis predicts a bistability between locked states due to a swallow-tail bifurcation, which is unique to the dual injection system. This bistability is confirmed experimentally and used as the basis for an all optical memory element with switching times below 500 ps.

AIRCRAFT PROPULSION SYSTEMS : A DIESEL HYBRID ENGINE

ABSTRACTRecent developments in diesel piston engine technology have increased performancein a very significant way. In this paper a new hybrid diesel-turbine engine is introducedand it is compared to up-to-date turboprops. The weak point of the common rail engineis the difficulty to obtain very fast injectors for large engines. Automotive injectors areavailable only for small power outputs. The problem was solved with a dual chamberspiston with two injectors per cylinder. It is then possible to use off-the-shelf automotivecommon rail components even on very large diesel engines with benefits oncombustion especially at medium low power level. The other more interestingadvantage is a significant increase on crankshaft maximum speed and reduction ofhead mechanical stress. It is then possible to have smaller and more powerfulturbodiesel and hybrid engines. Another advantage is the improved reliability of a dualinjection system. The diesel – turbine hybrid power unit proposed in this papercombines the advantages of the turboprop/turbofan/turboshaft and piston turbo-dieselprop/ turbo-diesel-fan / turbodiesel engines. However, It should be clear than theautomotive commercial common rail components should be treated to use jp4, jp8 andjet(A1) fuels and to fulfil aeronautical requirements.

Preconcentration and speciation of chromium in a sequential injection system incorporating dual mini-columns coupled with electrothermal atomic absorption spectrometry

A procedure for chromium preconcentration and speciation with a dual mini-column sequential injection system coupled with electrothermal atomic absorption spectrometry (ETAAS) was developed. At pH 6, the sample solution was firstly aspirated to flow through a Chlorella vulgaris cell mini-column on which the Cr(III) was retained. The effluent was afterwards directed to flow through a 717 anion exchange resin mini-column accompanied by the retention of Cr(VI). Thereafter, Cr(III) and Cr(VI) were eluted by 0.04 mol L − 1 and 1.0 mol L − 1 nitric acid, respectively, and the eluates were quantified with ETAAS. Chemical and flow variables governing the performance of the system were investigated. By using a sampling volume of 600 µL, sorption efficiencies of 99.7% for Cr(III) and 99% for Cr(VI) were achieved along with enrichment factors of 10.5 for Cr(III) and 11.6 for Cr(VI), within linear ranges of 0.1–2.5 µg L − 1 for Cr(III) and 0.12–2.0 µg L − 1 for Cr(VI). Detection limits of 0.02 µg L − 1 for Cr(III) and 0.03 µg L − 1 for Cr(VI) along with RSD values of 1.9% for Cr(III) and 2.5% for Cr(VI) (1.0 µg L − 1 , n = 11) were obtained. The procedure was validated by analyzing a certified reference material of GBW08608 and further demonstrated by chromium speciation in river and tap water samples.

Dual-Injection System with Multiple Injections for Determining Bidimensional Retention Indexes in Comprehensive Two-Dimensional Gas Chromatography

A new instrumental approach for collection of retention index data in the first (1D) and second (2D) dimensions of a comprehensive two-dimensional (2D) gas chromatography (GCxGC) experiment has been developed. First-dimension indexes were determined under conventional linear programmed temperature conditions (Van den Dool indexes). To remove the effect that the short secondary column imposes on derived 1D indexes, as well as to avoid handling of pulsed GCxGC peaks, the proposed approach uses a flow splitter to divert part of the primary column flow to a supplementary detector to simultaneously generate a conventional 1D chromatogram, along with the GCxGC chromatogram. The critical 2D indexes (KovAts indexes) are based upon isovolatility curves of normal alkanes in 2D space, providing a reference scale against which to correlate each individual target peak throughout the entire GCxGC run. This requires the alkanes to bracket the analytes in order to allow retention interpolation. Exponential curves produced in the 2D separation space require a novel approach for delivery of alkane standards into the 2D column by using careful solvent-free solid-phase microextraction (SPME) sampling. Sequential introduction of alkane mixtures during GCxGC runs was performed by thermal desorption in a second injector which was directly coupled through a short transfer line to the entrance of the secondary column, just prior to the modulator so that they do not have to travel through the 1D column. Thus, each alkane mixture injection was quantitatively focused by the cryogenic trap, then launched at predetermined times onto the 2D column. The system permitted construction of an alkane retention map upon which bidimensional indexes of a 25-perfume ingredient mixture could be derived. Comparison of results with indexes determined in temperature-variable one-dimensional (1D) GC showed good correlation. Plotting of the separation power in the second dimension was possible by mapping Trennzahl values throughout the 2D space. The methodology was applied to the separation of a standard mixture composed of 25 analytes (very diverse in polarity and structure) suspected to be allergens in perfume samples. The method will allow straightforward determination of temperature-variable retention indexes of target analytes.

Microcrystalline/Amorphous Thin Si Films Deposition by a Newly Developed Dual Injection System Employing Hydrogen Plasma and Silicon Radicals at Low Temperature (300 °C) Chemical Vapor Deposition Process

Low temperature (300 °C) deposition of thin microcrystalline/amorphous silicon films by using newly developed single shower, dual injection, microwave excited high density plasma (1011 cm-3) system is described. This is an original setup based on an experimental modification of a dual shower system that was reported by us earlier. For the first time, for this system, experimental results are presented correlating between the deposition and plasma parameters with the resulting Si films atomic structure. The results consistent interdependence enables to pre-determine, in a wide range, by design, the growth of microcrystalline or amorphous thin Si films, by setting the proper deposition conditions for each film type.

A new dual injection system for AMS facility

In order to measure long-lived radioisotopes such as 10Be with high sensitivity using an HVEE model 4130 AMS system, as well as to guarantee 14C measurements of high precision, a new dual injection system for the AMS system is proposed. The proposal is to add a Wien filter located between the ion source system and the recombinator of the HVEE model 4130. When a pulsing voltage is optionally applied to the Wien filter, a sequential injection mode is turned on. The isotopes would alternately pass on different trajectories through the recombinator. When the pulsing voltage and magnetic field are turned off, the Wien filter acts as a field-free drift space and the standard simultaneous injection mode is on. Beam optics calculation show that the new dual injection system will increase the number of radio-nuclides which can be analyzed, keep the high precision capability for radiocarbon dating and achieve high sensitivity for 10Be and 26Al measurements, together with simplifying the layout as compared to existing dual-injector and dual high-energy beam line systems.

Characteristics of Dual Transverse Injection in Scramjet Combustor, Part 2: Combustion

The combustion characteristics of a dual transverse injection system in a scramjet combustor were studied with numerical methods. The effects of the jet-to-crossflow momentum flux ratio and the distance between injectors on combustion characteristics were investigated. It is shown that the dual injection system has very different combustion characteristics with respect to the single injection system; the burning process of the rear injection flow is strongly influenced not only by the blockage effects but also by the preheating effects due to the chemical reactions of the front injection flow. The dual injection system has a higher burning rate and a higher flame height but more loss of stagnation pressure than the single injection system. It is also shown that there is an optimal distance between injectors for combustion characteristics and that the optimal distance increases as the jet-to-crossflow momentum flux ratio increases.

Characteristics of Dual Transverse Injection in Scramjet Combustor, Part 1: Mixing

The mixing characteristics of a dual transverse injection system in a scramjet combustor were studied with numerical methods. The effects of the jet-to-cross-flow momentum flux ratio and the distance between injectors on mixing characteristics were investigated. Three-dimensional Navier–Stokes equations, including the k–! SST turbulencemodel,weresolvedwiththe finitevolumemethodadoptingtheupwindmethodofEdwards’lowdiffusion flux splitting scheme. It is shown that the mixing characteristics of a dual transverse injection system are very differentfromthoseofasingleinjectionsystem.Therearinjection flowisstronglyinfluencedbyblockageeffectsdue to the momentum flux of the front injection flow and thus has higher expansion and penetration than the front injection flow. The dual injection system has a higher mixing rate and a higher penetration but have more losses of stagnation pressure than the single injection system. It is also shown that there is an optimal distance between injectors for mixing characteristics and that the optimal distance increased as the jet-to-cross-flow momentum flux ratio increased.

Speed-controlled particle injection into a low-pressure system

Protection of extreme ultraviolet lithography (EUVL) masks from any particles (existing inside the manufacturing process or particles generated by equipment motion) is a major concern for the success of deploying the EUVL technology. Under the low-pressure levels (e.g., ⩽50mTorr) in EUVL scanners, thermophoresis is considered as the most promising noncontact method to protect mask surfaces from any possible particle contamination during vacuum exposure. In order to better test the protection capability of thermophoresis we developed a method to supply particles with known speed into a low-pressure chamber (equipped with thermophoresis testing capability) by incorporating a dual stage particle injection system. The particle injection speed could be controlled by the volumetric flow rate through a critical orifice, the cross-sectional area of an injection tube, and the pressure ratio between the two stages. In addition, the length of the particle injection tube into the low-pressure chamber must be long enough to accurately predict the particle speed. The required tube length can be estimated by means of the particle stopping distance and a particle speed adjustment distance. Finally, the use of an axial jet arrangement for the critical orifice delivered particles through the center of the injection tube at known speed.

Evaluation of remedial alternatives for a petroleum contaminated unconfined aquifer with fluctuating groundwater level

This study evaluated remedial alternatives for a petroleum-contaminated site where an unconfined aquifer composed of a sandy layer of about 3–3.5 m thickness is covered by alluvial deposits and reclaimed soil of about 1.5 m thickness. Precambrian gneiss, of low permeability, lies below the sandy layer. The shallow water table is about 3 m below the surface, but shows high fluctuations of up to 1.5 m in response to precipitation events. The unsaturated soil near the water table and the groundwater are highly contaminated with petroleum hydrocarbons, especially toluene, which have apparently leaked from storage tanks. Selection of the remedial alternatives required consideration of the relevant laws on soil and groundwater conservation in Korea, the results of risk analysis and the hydrogeological conditions. The contaminated area has been divided into zones in which different remediation goals are set based on risk analysis and the degree of natural attenuation. It is estimated that the clean-up goal can be achieved in two years by the combined use of a trench drain and well point pumping to collect the contaminated groundwater for treatment, and a dual air injection system for the contaminated soil.

The optimised mixture formation for hydrogen fuelled engines

Both intake port injection type and in-cylinder injection type hydrogen fuel supply systems are designed for a single-cylinder research engine to investigate the effect of mixture formation on the performance of the hydrogen-fuelled engines. The intake port injection is superior in thermal efficiency and engine operation stability at low load conditions. However, the in-cylinder injection is superior for high load condition. In an engine experiment with throttling condition, the engine with intake port injection operates more stably and efficiently when fuel–air equivalence ratio is maintained above a certain level despite the pumping loss due to stable combustion. Thus, the hydrogen-fuelled engines can be operated more stably with the in-cylinder injection at high load and more efficiently with the intake port injection at low load. Therefore, the optimised operation of the hydrogen-fuelled engines can be achieved with a dual injection system and throttle valve control.